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DRAUGHTSMAN CIVIL, NSQF LEVEL - 5, , 1st Year (Volume II of II), TRADE THEORY, SECTOR:Construction, , DIRECTORATE GENERAL OF TRAINING, MINISTRY OF SKILL DEVELOPMENT & ENTREPRENEURSHIP, GOVERNMENT OF INDIA, , NATIONAL INSTRUCTIONAL, MEDIA INSTITUTE, CHENNAI, Post Box No. 3142, CTI Campus, Guindy, Chennai - 600 032, , Copyright Free under CC BY Licence

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Sector, , : Construction, Construction Material & Real Estate Duration : 2 - Years, , Trades, , : Draughtsman Civil 1st Year (Volume II of II) - Trade Theory - NSQF LEVEL - 5, , First Edition : October 2018, Copies : 1000, , Rs. 275/-, , All rights reserved., No part of this publication can be reproduced or transmitted in any form or by any means, electronic or mechanical,, including photocopy, recording or any information storage and retrieval system, without permission in writing from, the National Instructional Media Institute, Chennai., , Published by:, NATIONAL INSTRUCTIONAL MEDIA INSTITUTE, P. B. No.3142, CTI Campus, Guindy Industrial Estate,, Guindy, Chennai - 600 032., Phone: 044 - 2250 0248, 2250 0657, Fax : 91 - 44 - 2250 0791, email : [email protected], [email protected], Website: www.nimi.gov.in, ii, , Copyright Free under CC BY Licence

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FOREWORD, The Government of India has set an ambitious target of imparting skills to 30 crores people, one out of every, four Indians, by 2020 to help them secure jobs as part of the National Skills Development Policy. Industrial, Training Institutes (ITIs) play a vital role in this process especially in terms of providing skilled manpower., Keeping this in mind, and for providing the current industry relevant skill training to Trainees, ITI syllabus, has been recently updated with the help of Mentor Councils comprising various stakeholder's viz. Industries,, Entrepreneurs, Academicians and representatives from ITIs., The National Instructional Media Institute (NIMI), Chennai, has now come up with instructional material to, suit the revised curriculum for Draughtsman Civil 1st Year (Volume II of II) Trade Theory NSQF, Level - 5 in Construction Sector under Semester Pattern. The NSQF Level - 5 Trade Theory will, help the trainees to get an international equivalency standard where their skill proficiency and, competency will be duly recognized across the globe and this will also increase the scope of, recognition of prior learning. NSQF Level - 5 trainees will also get the opportunities to promote life long, learning and skill development. I have no doubt that with NSQF Level - 5 the trainers and trainees of ITIs,, and all stakeholders will derive maximum benefits from these IMPs and that NIMI's effort will go a long, way in improving the quality of Vocational training in the country., The Executive Director & Staff of NIMI and members of Media Development Committee deserve appreciation, for their contribution in bringing out this publication., Jai Hind, , RAJESH AGGARWAL, , Director General/ Addl. Secretary, Ministry of Skill Development & Entrepreneurship,, Government of India., , New Delhi - 110 001, , iii, , Copyright Free under CC BY Licence

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PREFACE, The National Instructional Media Institute (NIMI) was established in 1986 at Chennai by then Directorate, General of Employment and Training (D.G.E & T), Ministry of Labour and Employment, (now under Directorate, General of Training, Ministry of Skill Development and Entrepreneurship) Government of India, with technical, assistance from the Govt. of the Federal Republic of Germany. The prime objective of this institute is to, develop and provide instructional materials for various trades as per the prescribed syllabi (NSQF LEVEL 5) under the Craftsman and Apprenticeship Training Schemes., The instructional materials are created keeping in mind, the main objective of Vocational Training under, NCVT/NAC in India, which is to help an individual to master skills to do a job. The instructional materials are, generated in the form of Instructional Media Packages (IMPs). An IMP consists of Theory book, Practical, book, Test and Assignment book, Instructor Guide, Audio Visual Aid (Wall charts and Transparencies) and, other support materials., The trade practical book consists of series of exercises to be completed by the trainees in the workshop., These exercises are designed to ensure that all the skills in the prescribed syllabus are covered. The trade, theory book provides related theoretical knowledge required to enable the trainee to do a job. The test and, assignments will enable the instructor to give assignments for the evaluation of the performance of a trainee., The wall charts and transparencies are unique, as they not only help the instructor to effectively present a, topic but also help him to assess the trainee's understanding. The instructor guide enables the instructor to, plan his schedule of instruction, plan the raw material requirements, day to day lessons and demonstrations., IMPs also deals with the complex skills required to be developed for effective team work. Necessary care, has also been taken to include important skill areas of allied trades as prescribed in the syllabus., The availability of a complete Instructional Media Package in an institute helps both the trainer and, management to impart effective training., The IMPs are the outcome of collective efforts of the staff members of NIMI and the members of the Media, Development Committees specially drawn from Public and Private sector industries, various training institutes, under the Directorate General of Training (DGT), Government and Private ITIs., NIMI would like to take this opportunity to convey sincere thanks to the Directors of Employment & Training, of various State Governments, Training Departments of Industries both in the Public and Private sectors,, Officers of DGT and DGT field institutes, proof readers, individual media developers and coordinators, but for, whose active support NIMI would not have been able to bring out this materials., , R. P. DHINGRA, EXECUTIVE DIRECTOR, , Chennai - 600 032, , iv, , Copyright Free under CC BY Licence

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ACKNOWLEDGEMENT, National Instructional Media Institute (NIMI) sincerely acknowledges with thanks for the co-operation and, contribution extended by the following Media Developers and their sponsoring organisations to bring out this, Instructional Material (Trade Theory) for the trade of Draughtsman Civil (NSQF LEVEL - 5) under Construction, Sector for ITIs., , MEDIA DEVELOPMENT COMMITTEE MEMBERS, Shri. V. Dhanasekaran, , _, , Assistant Director of Training (Retd.),, MDC Member,, NIMI, Chennai - 32, , Shri. G. Jeyaraman, , _, , Assistant Training Officer (Retd.),, MDC Member,, NIMI, Chennai - 32, , Shri. S. Mohan, , _, , Assistant Training Officer,, Govt. I.T.I (North Chennai),, DET, Tamil Nadu, , Shri. G. Michael johny, , _, , Assitant Manager,, Co-ordinator,, NIMI, Chennai - 32, , NIMI records its appreciation for the Data Entry, CAD, DTP operators for their excellent and devoted services in, the process of development of this Instructional Material., NIMI also acknowledges with thanks the invaluable efforts rendered by all other NIMI staff who have contributed, towards the development of this Instructional Material., NIMI is also grateful to everyone who has directly or indirectly helped in developing this Instructional Material., , v, , Copyright Free under CC BY Licence

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INTRODUCTION, Trade Theory, The manual of trade theory consists of theoretical information for the first semester course of the Draughtsman, Civil under NSQF - Level 5. The contents are sequenced according to the practical exercise contained in the, manual on trade practical. Attempt has been made to relate the theoretical aspects with the skill covered in each, exercise to the extent possible. This correlation is maintained to help the trainees to develop the perceptional, capabilities for performing the skills., The trade theory has to be taught and learnt along with the corresponding exercise contained in the manual of, the trade practical. The indications about the corresponding practical exercises are given sheet of this manual., It will be preferable to teach/learn trade theory connected to each exercise at least one class before performing, the related skill in the shop floor. The trade theory is to be treated as an integrated part of each exercise., The material is not the purpose of self-learning and should be considered as supplementary to class room, instruction., Trade Practical, The trade practical manual is intended to be used in practical workshop /Hall. It consists of a series of practical, exercises to be completed by the trainees during the second semester course of Draughtsman Civil under, NSQF Level - 5 Syllabus, which is supplemented and supported by instructions / informatics to assist in, performing the exercises. These exercises are designed to ensure that all the skills in prescribed syllabus are, covered., Module 1 - Chain Surveying, Module 2 - Surveying, Module 3 - Plane table surveying, Module 4 - Levelling and contouring, Module 5 - Theodolite surveying, Module 6 - Carpentry joints, Module 7 - Electrical wiring, Module 8 - Floor, Module 9 - Vertical movememt, Module 10 - Roof & roof covering, The skill training in the shop floor is planned through a series of practical exercise centered around some, practical object. However, there are few instances where the individual exercise does not from a part of project., , vi, , Copyright Free under CC BY Licence

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Lesson No., , Title of the Lesson, , Page No., , Module 1 : Chain surveying, 2.1.41, , Introduction - History and principles of chain survey and instrument & employed, , 1, , Introduction and terms used, , 12, , 2.1.42 - 44, , Introduction about chain survey instruments, , 15, , 2.1.45, , Knowledge of mouza map, , 22, , Module 2 : Compass surveying, 2.2.46, , Identification and Parts of instruments in compass survey, , 25, , 2.2.47 - 50, , Determining the bearings of a given triangular plot of ABC and calculation of, included angles, , 33, , Determining the bearings of a given pentagonal plot of ABCDE and calculating, included angles, , 39, , Magnetic declination and local attraction, , 45, , Module 3 : Plane table surveying, 2.3.51 & 52, , Instrument used in Plane table surveying, , 56, , Method of plane table survey, , 59, , Traversing method of plane table survey, , 60, , Resection method of plane table survey, , 61, , Locate and plot new building by two point and three point problem, , 62, , Inking, finishing , colouring and tracing of plane table map, , 66, , Module 4 : Levelling and contouring, 2.4.53 & 54, , Principle of levelling - Auto level - Dumpy level- Tilting level, , 69, , 2.4.55 & 56, , Levelling staff - Its Graducation & Type, , 72, , 2.4.57 - 59, , Holding of levelling staff - Temporary adjustments, , 74, , Level field book, , 76, , Problems on levelling, , 78, , Types of levelling, , 81, , Fly levelling & check levelling, , 85, , Problem on reduced levels, , 85, , Reciprocal levelling, , 87, , Longitudinal sectioning and cross sectioning, , 89, , Errors in levelling, , 93, , Introducing to contouring, , 94, , Uses of contours, , 95, , Interpolation of contours, , 97, , Contour gradient, , 98, , 2.4.60, , 2.4.61, , 2.4.62 - 65, , vii, , Copyright Free under CC BY Licence

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Lesson No., , 2.4.66 - 68, , Title of the Lesson, , Page No., , Uses of contours and direct method, , 99, , Road projects, , 100, , Indirect method of contouring, , 103, , Topography and contour, , 104, , Map Reading, , 105, , Trignometric levelling (Indirect levelling), , 105, , Module 5 : Theodolite, 2.5.69, , Introduction to theodolite, , 111, , 2.5.70 & 71, , Main parts of vernier theodolite - I, , 112, , Main parts of a vernier theodolite -II, , 114, , Main parts of a vernier theodolite -III, , 115, , Fundamental axes and geometry of theodolite, , 117, , Definitions and terms, , 119, , Unplacing and placing theodolite, , 120, , Prolonging a line, , 121, , Running a straight line between two points, , 122, , Intersection of two straight lines, , 123, , Temporary adjustments of theodolite, , 125, , Permanent adjustments, , 126, , Instrumental errors, , 130, , Natural errors, , 131, , Personal errors and mistakes, , 131, , Reading a theodolite, , 133, , Theodolite - measuring horizontal angle - ordinary method, , 134, , Theodolite - measuring horizontal angle - repetition method, , 134, , Theodolite - measuring horizontal angle - reiteration method, , 136, , Measuring vertical angle, , 137, , Deflection angle & Direct angle, , 140, , Traverse, , 141, , Traverse checking, , 142, , Classification of traverse, , 143, , Theodolite traversing methods - I, , 144, , Theodolite traversing methods - II, , 145, , Theodolite traversing phases, , 146, , Closing error, , 147, , Latitudes and departures, , 148, , Balancing the traverse, , 149, , 2.5.72 & 73, , 2.5.74, , 2.5.75, , 2.5.76, , 2.5.77, , viii, , Copyright Free under CC BY Licence

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Lesson No., , Title of the Lesson, , Page No., , Module 6 : Carpentry joints, 2.6.78, , 2.6.79 & 80, , Carpentary joints - I, , 156, , Carpentry joints - II, , 160, , Types of doors - I, , 165, , Types of doors - II, , 169, , Types of doors - III, , 172, , Windows and ventilators, , 174, , Fixtures and fastenings, , 179, , Module 7 : Electrical wiring, 2.7.81, , 2.7.82, , Safety Precaution, , 183, , Safety signs, , 184, , Basic first- aid treatment, , 185, , Electrical safety, , 191, , Safety practice - first aid, , 192, , Elementary of electricity, , 194, , Wiring - Electrical, , 196, , Trade hand tools - specification, , 200, , Domestic wiring installation, , 207, , Inspection and testing of wiring installations - Method of improving test results IE Regulations, , 212, , Diagrams and systems used in domestic installation, , 213, , BIS Regulations, recommendations and NE code pertaining to wiring installations, , 214, , Simple electrical circuit and its elements, , 215, , Types of electrical supply, , 218, , Polarity test in DC, , 219, , Module 8 : Floor, 2.8.83, , Floor (Ground), , 223, , 2.8.84, , Upper floors, , 228, , Module 9 : Vertical movement, 2.9.85, , 2.9.86, , 2.9.87, , Vertical transportation, , 231, , Stairs, , 233, , Classification of stairs according to shape, , 237, , Classifications stair according to material and requirements of good stair, , 239, , Lift or elevators, , 244, , Moving stairs (escalator), , 245, , ix, , Copyright Free under CC BY Licence

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Lesson No., , Title of the Lesson, , Page No., , Module 10 : Roof & roof covering, 2.10.88, , Roofs, , 246, , 2.10.89, , Trussed roof, , 251, , Flat roof, , 254, , Curved roof, , 257, , Roof covering for pitched roofs, , 259, , 2.10.90, , ASSESSABLE / LEARNING OUTCOME, On completion of this book you shall be able to, . Perform site survey with chain / tape and prepare site plan., . Perfom site survey with prismatic compass and prepare site plan., . Perform site survey with plane table and prepare site plan., . Make topography map / contour map with leveling instrument., . Perform site survey with Theodolite and prepare site plan., . Drawing of different types of carpentry joints., . Draw different types of doors and windows according to, manner of construction, Arrangement of component, and, working operation., . Prepare the detailed drawing of electrical wiring system., . Draw types of ground and upper floors., . Draw different types of vertical movement according to shape, location,, materials in stair, lift, ramp and escalator, . Draw different types of roofs according to shape, construction, purpose, and span., , x, , Copyright Free under CC BY Licence

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1st, , Year (Volume II of II), , SYLLABUS FOR DRAUGHTSMAN CIVIL, , Week, No., , Ref. Learning, Outcome, , 27-30, , Performsitesurvey, with chain / tape and, prepare site plan., Perfom site survey, using prismatic, compass., Perform site survey, with plane table and, prepare a map., , 31-34, , Make tropography, map by contours with, leveling instruments., , Professional Knowledge, (Trade Theory), with Indicative hours, Surveying:Chain Survey :- (55 hrs.), 41. Equipment, and, instrument used to, perform surveying., 42. Distance measuring with, chain and tape., 43. Entering Field book and, plotting., 44. Calculating the area of, site., 45. Prepare site planwith the, help of Mouza map., Compass survey:(40 hrs), 46. Field work of prismatic, compass survey., 47. Plotting of prismatic, compass survey., 48. Testing and adjusting the, compass., 49. Observation of bearings., 50. Bearing a line., 51. F.B.,B.B., R.B.,W.C.B. of, a Line,Traverse and also, check, the, close, traversing. Plane Table, Survey :- (17 hrs), 52. Surveying of a Building, site with Plane Table., Levelling:- (112 hrs.), 53. Handling of levelling, instruments & their, settings, 54. Temporary adjustment of, alevel., 55. Simple levelling., 56. Differential levelling (Fly, levelling)., 57. Carry out Levelling field, book., 58. Equate Reduction of, levels –, Height of collimation and, Rise and Fall method –, Comparison of methods., 59. Solve problems on, reduction of levels., 60. Calculate Missing data, and how to fill it up–, , Duration: Six Month, Professional Skills, (Trade Practical), Surveying:• Introduction, History and, principles of chain survey., • Instrument employed., • Use, care, maintenance and, common terms., • Classification, accuracy,, types., • Main divisions (plane &, geodetic)., • Chaining., • Speed in field and office, work., • Knowledge of Mouza Map., Compass survey:• Instrument and its setting up, • Bearing and each included, angle of close traverse., • Local attraction., • Magnetic declination and its, true bearing., • Precaution in using prismatic, compass., Plane table survey:• Instrument used in plane, table survey, • Care and maintenance of, plane table, Levelling:• Auto level , dumpy Level,, Tilting Level - introduction,, definition, • Principle of levelling., • Levelling staffs, its graduation, & types., • Minimum equipment, required, • Types,component / part and, function., • Temporary and permanent, adjust ment, procedure in, setting up., • Level& horizontal surface., Datum Benchmark, Focussing, & parallax, • Deduction of levels / Reduced, Level., , Copyright Free under CC BY Licence

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calculations & Arithmatical checkin, various problems and its solution., 61. Practice leveling with, different instruments., 62. Check levelling., 63. Profile levelling or, Longitudinal, plotting the, profile., 64. Surveying of a building site with chain, and Levelling Instrument with a view, to computing earth work., 65. Contour - Direct and Indirect methods., 66. Make Topography map,, contours map., 67. Solve trigonometric problems., 68. Prepare a road project in a certain, alignment., 35-37, , Perform a site survey, with Theodolite and, prepare site plan., , 38-39 Drawing of different, types of carpentry, joints., Draw different types of, doors and windows, according to Manner of, construction,, Arrangement of, component, and, working operation, , Theodolite survey:Field work of theodolite., Horizontal angle., Vertical angle., Magnetic bearing of a line., Levelling with a theodolite., Calculation of area from, traverse., 75. Determination of Heights., 76. Calculation of departure,, latitude, northing and easting, - (Total 56 hrs), 77. Setting out work-Building,, culvert, centre line of Dams,, Bridges and Slope of Earth, work, etc. (28 hrs), 69., 70., 71., 72., 73., 74., , Making detailed drawing of :78.Carpentry, joints:, lengthening,, bearing, housing, framing,, panelling & moulding. (22, hrs), 79. Different Types doors, including panelled, glazed, and flush door. (22 hrs), 80. Different types windows, and ventilators. (12 hrs), Electrical Wiring:Prepare drawing of, , • Types of leveling, Application, to chain and Levelling, Instrument to Building, construction., Contouring ;-Definition,, Characteristics, Methods., Direct and Indirect methods, Interpolation of Contour,, Contour gradient , Uses of, Contour plan and Map., Knowledge on road project., , •, •, •, •, , Theodolite survey:• Introduction., • Types of theodolite., • Uses, Methods of Plotting., • Transit vernier theodolite., • Terms of transit theodolite., • Fundamental line of, theodolite., • Adjustment of theodolite., • Checks, Adjustment of errors., • Open and closed traverse and, their application to, Engineering Problems., • Vernier scale- types., • Measurement of horizontal, angle., • Measurement of vertical, angle., • Adjustment of a close, traverse., • Problems in transit, theodolite-departure,, latitude, northing and, easting., , • Carpentry joints :-terms,, •, •, •, , classification of joints, Uses,, types of fixtures , fastenings., Doors ¡VParts, Location,, standard sizes, types., Windows-types., Ventilators-purpose-types., , Copyright Free under CC BY Licence

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81. Wiring in different system., (08 hrs), 82. Electrical wiring plan with all, fittings showing in drawing., (20 hrs), 40, , 41-42, , 43-44, , 45-47, , Prepare the detailed, drawing of electrical, wiring system., , Electrical Wiring:Prepare drawing of, 81. Wiring in different s y s t e m ., (08 hrs), 82. Electrical wiring plan with all, fittings showing in drawing. (20, hrs), , Draw types of ground, and upper floors., , Drawing details of:83. Types of ground & upper, floors. (28 hrs), 84. Various floor finishing,, sequence of construction., (28 hrs), , Draw types of vertical, movement according, to shape, location,, materials by using, stair, lift, ramp and, escalator., , Draw different types, of, roofs truss according, to, shape, construction,, purpose and span, , Drawing different forms ofvertical, movements:85. As per shape - Drawing of, straight, open newel,, doglegged, geometrical and, bifurcated stairs & spiral, stairs. (18 hrs), 86. As per material - brick,, stone, wooden, steel & RCC, stairs. (20 hrs), 87. Drawing of Lift and, Escalator., (18 hrs), Drawing details of:88. Slopped/Pitched Roof Truss King Post and Queen Postroof, trusses showing detailed, connections., (32 hrs), 89. Steel roof trusses showing, detailed connections., (30 hrs), 90. Wooden roof truss, showing, detailed connections., (22 hrs), , Electrical Wiring:• Safety precaution and, elementary first aid., • Artificial respiration and, treatment of electrical shock, • Elementary electricity., • General ideas of supply, system., • Wireman¡¦s tools kit. Wiring, materials. Electrical fittings., • System of wirings. Wiring, installation for domestic, lightings., , • Floors - Ground floor & upper, floor - Types., , • Flooring - materials used, types., , • Stairs:- Terms. Requirements,, Planning and designing of, stair and details of, construction., Basic concept of lift and, Escalator, , •, , Roofs & Roof coverings: -, , • purposes,Elements, Types,, Fla, pitched., , • Truss-king post, queen post,, •, •, •, , mansard, bel-fast, steel,, composite., Shell-types-north-light &, double curved., Dome. Components parts., Roof & coverings - objectives,, types & uses., , Copyright Free under CC BY Licence

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48-49, , Project work / on the job training, Broad area :(a) Prepare site map using chain/prismatic compass/plane table / leveling instrument/, theodolite., (b) Prepare innovative drawing/model of doors/ windows., (c) Prepare innovative drawing/model of vertical movement/roofs., , 50-51, , Revision, , 52, , Examination, , Note: 1. Some of the sample project works (indicative only) are given against each semester., 2. Instructor may design their own project and also inputs from local industry may be taken for designing, such new project., 3. The project should broadly cover maximum skills in the particular trade and must involve some problem, solving skill., 4. If the instructor feels that for execution of specific project more time is required than he may plan, accordingly to produce part/ sub-drawings in appropriate time i.e., may be in the previous semester or, during execution of normal trade practical., 5. Drawings at weeks 1 to 54 are in traditional and from 55 to 99 weeks are in computer drafting., , Copyright Free under CC BY Licence

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Construction, Draughtsman Civil - Chain surveying, , Related Theory for Exercise 2.1.41, , Introduction - History and principles of chain survey and instrument & employed, Objectives : At the end of this lesson you shall be able to, • define surveying, • explain the classification of surveying, • narrate different methods of measurements, • express the instruments used for chain surveying., Introduction, Land surveying is the science of determining the position, of points on the landscape and the distance and angles, between them. Land surveying plays a vital part in the, beginning of a construction project. Properly surveyed, land helps to establish property boundaries. The, elevations of different points of construction site are vital, for engineers then only can formulate the appropriate, designs or plans. Another use of land surveying is, subdividing land. Surveying is done to determine where, a road or a building or any engineering project will be, placed. Any error occured in surveying will result the, project cost steep high and it may affect the safety of, project also., , introduced. The Great Trigonometeric Survey of India, began in 1801. The Indian survey had an enormous, scientific impact. It was responsible for one of the first, accurate measurements of a section of an arc of, longitude. It named and mapped Mount Everest., Surveyors laid out canals, road and rail playing a pivotal, role in Industrial Revolution., Theodolite total station and GPS survey are the commonly, used surveying instrument in 21st century. Aerial surveying, techniques, remote sensing and satellite survey improved, and become cheaper. New technologies like threedimensional (3D) scanning and Lidar are gathering, momentum in land surveying., Some specific use of surveying, , Planning and design of all Civil Engineering project such, as alignment of road, canal, railway, water supplies,, sanitation etc. of any magnitude is constructed along the, lines and points established by surveying. Surveying is a, basic requirement for all Civil Engineering projects., , •, , Survey output is used for determining area, volume., , •, , Survey involves surveying existing conditions of the, work site., , •, , Stake out building corners and grids., , Surveying details are used in transportations,, communications, nation security, policy making, environmental regulations, mapping, and the definition, of legal boundaries for land ownership., , •, , Stake limit of work., , •, , Stake out reference points., , •, , Marking floor levels., , Definition, , •, , Verify the location of structures during construction., , •, , Verify that the work authorized was completed to the, specifications set on plans, , •, , Provide horizontal control on multiple floor, , Surveying is the art of making linear or angular, measurements in horizontal plane or vertical plane to, determine the relative positions of points on the surface, of the earth or beneath the surface of the earth., , Other principal works in which surveying is primarily, utilized are, , Ancient Surveying, Evidence shows that basic surveying techniques used in, 1400 BC in ancient Egypt. There is a representation of, land measurement on the wall of a tomb at Thebes (1400, BC) men measuring a grain field. They used marked, rope and wooden rods for measuring distance. The, Romans recognized land survey as a profession. They, used some standard tools for basic measurement., Modern Surveying, Modern surveying starts with the introduction of more, refined standard tools including instrument for measuring, direction. Triangulation and resection method were, , •, , To fix the national and state boundaries., , •, , To chart coastlines, navigable streams and lakes., , •, , To establish control points and, , •, , To prepare topographic map of land surface of the, earth., , Surveyor: A person performing operation to obtain the, requirement measurements, distance, directions, etc. to, prepare plan or map is known as surveyor., , 1, , Copyright Free under CC BY Licence

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Duty of a Surveyor, , 1 Plane surveying, , A surveyor plays a pivotal role in any engineering project., A surveyor should possess all leadership quality, should, be punctual and responsible, know time and resource, management techniques, , The surveying in which the earth surface is assumed as, plane and the corrective of the earth is original is known, as plane surveying. As the plane surveying extends only, small area the lines connecting any two points on the, surface of the earth are treated as straight line and the, angles between these lines are taken as plane angles., Survey is covering area 200 sq.km may be treated as, plane surveying. This is because of difference in length, between the arc and its subtended chord on the surface, of the earth for a distance of 18.2 sq.km only 10cm., , A surveyor should also have engineering thinking, capabilities and decision making capabilities., A surveyor's duty can be mainly classified into three, 1 Care and adjustment of instrument, 2 Field work, , 2 Geodetic surveying, , 3 Office work, , The survey which the corrective of the earth surface is, taken into account and a higher degree of precision is, exercised in linear and angular measurements is termed, as geodetic surveying. Such survey extended over the, longer area. A line connecting two points is regarded as, an arc and the angles between the intersecting line are, spherical angles., , Surveying, Levelling: Levelling is the branch of surveying which, deals with the measurements of relative height or depth, of different point on the surface of the earth is known as, levelling., Object of surveying: The main object of surveying is, the preparation of plan or map of an area. In olden days, the surveyors were performed only for the purpose of, reaching the boundaries of plot. But due to the, advancement in technology the science of surveying has, also attaining its due importance. The layout of alignment, of road, railway, canal, tunnel, transmission power lines,, microwave or television, relaying towers and water, supplies or sanitary scheme etc. are requirement a very, accurate map i.e. the success of these engineering project, is based upon the accurate and complete survey work., Therefore, an engineer must be thoroughly familiar with, the principle and different method of surveying and, mapping., Plan: A plan is a graphical representation of features on, the earth surface or below the earth surface on horizontal, plane in a largest scale compared to map (i.e. a smaller, area surveyed), Map: A map is a graphical representation of features on, the earth surface or below the earth surface as projected, on a horizontal plane in a smaller scale compare to plan, (i.e. larger area surveyed), Classification of surveying, Classification based on the accuracy surveying, The Surveying may be divided into two, 1 Plane surveying, 2 Geodetic surveying, , 2, , Classification based upon the nature of the field of, surveying, 1 Land surveying, 2 Marine or navigation or hydrographical surveying, 3 Astronomical surveying, 1 Land surveying, It consists of re-running old land line to measure to, determine the length and direction. Sub-dividing land into, pre-determined shape and size and calculating the areas, and survey stories and locating position. Land survey, can be sub-divided into following:, a Topographical survey: It is for the determined by the, natural as well as artificial features of a country such, as hills, valleys, rivers, lakes, woods, railways, canals,, building, town, village etc., b Cadastral survey: The survey in which area generally, plotted to a larger scale than the topographic survey, and are carried out for fixing the property land, preparation of revenue maps of states are called, cadastral survey. These are also sometimes used, for fixing boundaries of municipality corporation or, candonment., c City survey: The survey which are carried out for the, construction of road, water supplying system, sewer, for any developing townships are called city survey., d Engineering survey: For determining quantities and, for collecting datas for design of engineering work such, as road, railway, reservoir or works in connection with, water supplies, sewage etc. enginerring survey may, be further divided into three., , Construction: Draughtsman Civil - (NSQF Level - 5) : Related Theory for Exercise 2.1.41, , Copyright Free under CC BY Licence

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I, , Reconnaissance survey: For determine the, feasibility and rough cost of the scheme., , II Preliminary survey: For collecting more precious, datas and choose the best location of the work and to, estimate the quantities and cost., III Location survey: For setting out the work on the, ground., 2 Marine or navigation or hydrographic survery, The Survey which deals with the mapping of large water, body for the purpose of navigation construction of harbour, work, prediction of tide and determination of sea level, are called marine or navigation or hydrographical survey., , Uses of surveying, Surveying may be regarded as an art and science of map, making. The art of surveying and mapping have been, practiced from very ancient time as their application has, become increasingly important as time as progressed., The earliest survey chiefly confined to measurements of, land and establishment of boundaries. The engineer must, be thoroughly familiar with the principles and practices of, surveying. Since all engineering and construction projects, such as highway, railway, irrigation, water supply etc. are, extending over large areas and are based upon elaborate, and complete the surveys. The value of land is, considerably increased in the present decade, so the, fixation boundary and division of plot is done carefully, and with very sophisticated instruments., , 3 Astronomical survey, Principles of survey, The survey which carried out for determining absolute, location of different places on the earth surface and, directions of any lines by making observation to heavenly, bodies, i.e. star and sun are called astronomical survey., , The two fundamental principles upon the various survey, methods based are, 1 To work from whole to part, , Classification based upon the object surface of, survey, , 3 Mine survey: For exploring mineral wealth such as, gold, coal, copper etc., , The main principle of survey plain or geodetic survey is, work from the whole to part.sufficient number of primary, control point are established with higher precision and, then around the area to be surveyed. Minor control points, in between the primary control points are then established, with less precise method, i.e. in general practice the area, is divided into a number of large triangles and the position, of their various of surveyed with greater accuracy by using, sophisticated instrument., , 4 Military survey: For determining points of strategic, importance of both offensive and defensive., , Units of measurements, , 1 Archeological survey: For determining unearthing, relics of antiquities, 2 Geological survey: For determining different stratus, of earth crust., , Classification of based upon the method employed, in the survey, , Metric, , British, , 10mm = 1cm, , 12 inches = 1 foot, , 10 cm = 1dm, , 3 feet = 1 yard, , 10dm = 1m, , 51/2 yard = 1 rod,, pole, perch, , Classification of based upon the instrument used, , 1000m = 1km, , 4 pole = 1 chain, , 1 Chain survey, , 10m = 1 decum, , 10 chain = 1 furlong, , 2 Compass survey, , 1 million = 1 mega, metric, , 8 furlung = 1 mile, 100 links, = 1 chain, , 1852m = 1 nautical, , 6 feet = 1 fathoms, , 1 hectometre =, 1000 cm2, , 120 fathoms = 1 cable, length, , 1 Triangulation survey, 2 Traverse survey, , 3 Plane table survey, 4 Theodolite survey, 5 Tacheomatric survey, 6 Photographic survey, , 6080feet = 1 nautical mile, , 7 Aerial survey, , 1 engineer chain = 100 feet, , Construction: Draughtsman Civil - (NSQF Level - 5): Related Theory for Exercise 2.1.41, , Copyright Free under CC BY Licence, , 3

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Basic unit of area, Metric, , British, , 100 sq.mm. = 1cm2, , 144 inch2 = 1 foot2, , 100cm2 = 1dm2, , 9sq.feet = 1sq. yard, , 100dm2 = 1m2, , 30 1/4 sq.yard = 1sq., rod, 1 sq. pole., , 100m2 = 1 acre, , 40sq.rod = 1sq.rod, , 100 acre = 1 hectare, , 144inch2 4 rods = 1, acre, , 100 hectares = 1km2, , 640 acre = 1sq. miles, , 1 cent = 40.47m, , 2, , 100 cent = 1 acre, , Polar co-ordinates (Fig 3 & 4), , 484 sq. yard = 1sq., chain, 100sq.chain = 1acre, , These triangles are further divided into smaller triangles, and their vertices are surveyed with lesser accuracy by, using these smaller triangles. The more interior details, are collected., The main idea of working from whole to the part is, prevented accumulation of errors and to localize minor, error within the frame works of control points on the other, hand smaller error are magnified., 2 To fix the position of new station by at least two, independent points., The new station is fixed from points already fixed by, a Linear measurement, b Angular measurement, , By the angle ∠ BAD measured at distance AD by the, according to the condition., By the ∠ BAD measured at B and distance AD or by the, DAB measured at A and distance BD. This method is, used when it is not possible to measure the distance to, the point from the point of reference at which the angle is, measured., , Triangulation (Fig 5), , c Both linear and angular measurement, According to the convenient methods locating convenient, points., Rectangular Co-ordinate (Fig 1), , By two angle BAD and ABD measured at A and B. This, method is used in traverse survey, Intersection (Fig 6 & 7), By perpendicular distance dD and distance Ad or by the, distance Bd., Trilateration (Fig 2), By two distance AD, BD. This method is chain surveying, , 4, , Construction: Draughtsman Civil - (NSQF Level - 5): Related Theory for Exercise 2.1.41, , Copyright Free under CC BY Licence

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of bicycle, etc and register the no. of revolution of wheel, knowing the circumference of wheel., 5 Speedo Meter: The Speedo meter is an automobile, may be used to measure distance approximately. It, gives better result than pacing provided the rout is, smooth., By the intersection of two straight line (AB and CE), between four known points A,B,C and E, By the two angles ADB and BDC measured at the point, “D” to be located with respect to three known points, reference and AB and CE, Linear measurement: Horizontal and vertical distance., Angular measurement: Horizontal and vertical angles., Measurements of distances: There are two main, methods of determine measurements of distances., , 6 Perambulator: Another method of rapid determination, of distance is by an instrument is called perambulator., It resembles simple bicycle wheel provided with a fork, and hand it is wheeled along the line whose length is, decided. The distance traverse automatically, registered by the dial., 7 Judging distance: It is a very rough method of, obtaining distance. It is used in estimating distance of, details in reconnaissance survey., 8 Time measurement: The distance is roughly, determined by line intervals of trend knowing the, average time per km by a person at the walk or horse., The distance travel may be readily obtained., , The distance is measured on the ground by means of, chain or tape or any other instrument., , 9 Chaining: Of the various method of measuring, distance the most accurate and common method is, the measuring distance with chain or tape is called, chaining., , 2 Computation Method, , Instrument used for Chaining, , There the distances are obtained by calculation, tachometry, or triangulations., , 1 Chain: Chain is composed of piece of galvanised mild, steel wire 4mm diameter (8 swg) called links. The end, of each links are bent into a loop and connected, together by means of 3 oval rings, which offers, flexibility to the chain. The end of the chain is provided, with brass handles for dragging and stretching chain, on the ground. Each with swivel joints so that the chain, can be turned around without twisting. The length of, a link is the distance between the centres of the two, connective needle rings. The end link includes the, handles, indicators (Talley) or distinctive pattern are, fixed at distinctive point on the chain to facilitate quick, readings of fractions of chain is in surveying, measurement., , 1 Direct Method, , Direct measurements, Several methods are available for measuring distance, according to the degree of accuracy and speed of the, work., 1 Pacing: Where approximate results are required, distance may be determined by pacing. The method, consisting working over a line and counting the number, of paces knowing the average length pace (which may, be taken as 80 cm) the required distance may be, obtained multiplying the no. of pace by the average, length of pace., 2 Passo meters: The monotony and strain of accounting, paces may be obtained by the use of an instrument, called paso meter. It is a pocket instrument resembling, a watch in size and appearance and automatically, records the number of paces taking pacing in a given, distance and calculate the distance as in pacing, method., 3 Pedo meter: It is a similar instrument and is used for, measuring distance. It registers the distance traversed, by the person carrying in it instead of number of pacing., We can adjust the length of one pace is according to, the site condition and person carry it., , The following chains are used in different countries, according to the unit of linear measurement. It is, classified into two namely., I, , Metric and, , II Non- Metric chain, i, , Metric chain: These chain is made in length of 20 m, and 30 m. The length of one link is 20 cm., , ii Non-metric chain, a Gunder’s chain: A gunter’s chains is 66 feet long and, is divided into 100 links each 0.66 feet long. It is very, convenient for measuring in distances in miles and, furlongs and area in acres., , 4 Odo Meter: The distance may be approximately by, means of a simple device is called as odometer.It can, be attached to the wheel of any vehicle such as carriers, Construction: Draughtsman Civil - (NSQF Level - 5): Related Theory for Exercise 2.1.41, , Copyright Free under CC BY Licence, , 5

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b Revenue chain: The revenue chin is commonly used, for measuring fields in cadastral survey. It is 33 ft., long and divided in to 16 links each 2 1/16 feet long., , and tear. Its length gets elongated when stretched and, shortens by sagging in a windy weather. This tape, cannot be used for accurate work., , c Engineers chain:The engineers chain is 100ft. long, and is divided into 100 links each one foot in length., , 2 Metallic tape: The linen tape when reinforced with, fine brass or copper wires to prevent stretching or, switching of fibres is known as metallic tape. These, wires are interwoven into the varnished strips and are, not visible to the naked eye. This tapes are available, in different length such as 2m, 5m, 10,15,20, 30m., Each metre length is divided into 10 equal parts, (decimetres) and each part divided into 10 parts, (centimetre) and it is commonly used for taking offset, chain surveying., , 2 Steel band, It is also called the band chain consist of a ribbon of, steel with brass swivel handles at each end. It is 20 or, 30m long. The graduation is marked in two ways., 1 The band is divided by studs at every 20cm and, numbered at every one metre. The first steel and, last link sub - divided into cm and mm., 2 The graduation is etched as metre, decimetre,, centimetre on one side and point 2 metre links all, the other. Brass tallies are fixed at every 5m length., It is used for accurate survey work., The following are the point on comparison between the, chain composed of link and band chain., Chain composed, of links, , Steel band or band chain, , 1 It can with stand rough, treatment., , If carelessly used it, gets broken., , 2 It can be easily reparied, with the hammer in the, field., , It can be repaired only, by soldering or riveting, , 3 It can be read easily., , It cannot be read so, easily., , 4 It is heavier and sags, considerably when, suspended., , It is lighter and doesn’t, sags to extent to, which chain sags., , 5 It is liable to easily increase or decrease in, length due to continous, use and bending of, links respectively., , It maintain length very, much better than the, chain., , 6 It is heavier and takes, more time to spread., , For the same length it, is lighter than chains, and easier to open., , 4 Invar Tape: For work of the highest precision the invar, type is generally used as in measurement of base line, to triangulation and in the city work. It is made up of, an alloy of steel and nickel (36%) and the co-efficient, of thermal expansion is 0.000000122 for PC. It is six, mm wide and may be obtained in the length 30, 50, and 100 m. It is very expensive and extremely delicate, and must be handled with greatest care to avoid, bending and kinking. It cannot be used for ordinary, work., Instrument used for marking station, 1 Pegs, , Tape, It is an instrument used for marking linear measurements, where the length is to be measured accurately. It is also, used for marking offsets distance different object from, the chain line. The tapes are generally classified according, to the material from which they are manufactured., 1 Linen or cloth tape: It is made out of linen or cloth, with brass handles at zero end and whose length is, included in the tape length. This tapes are availble in, different lengths such as 10, 20 and 30m. This tapes, are light and handy and cannot with stand much wear, 6, , 3 Metric steel tape: The denomination of the tapes, measures is 1,2,10,30 and 50m. The tape is of steel, or stainless steel. The outer end of the tape is provided, with a long ring. The length of the tape included the, metal ring provided. The tapes are marked legibly on, one side only with a line every 50 mm and at every, cm. dm and m. The first decimetre having the marked., Every decimeter and metre shall be marked with, Hindu, Arabic, numerals with bold type. In metre, division in addition bears the designation ‘m’. Every, centimeter in the first decimeter shall be marked with, Hindu Arabic numerals. The end of tape measure of, denomination 10,30 and 50 m is marked with the, words metre., , Wooden pegs are used to mark the position of station., They are made up of hard timber and are tapered at one, end. They are usually 25 cm square and 15 cm long. But, in soft ground pages 40 to 60 cm long and 4-5 cm square, are suitable. They should firmly driven in the ground with, steel hammer with about 4 cm projecting above the, surface of the ground, instead of wooden pegs 10mm, diameter steel rods are used., 2 Ranging Rod, The ranging rods are used to marking the position for, station for ranging the lines. They are made up of well –, seasoned straight grained timber of teak. Blue pine or, deodar. They are circular or octagonal in cross sectional, on 3cm, nominal diameter and show cross shoe 15 cm, long the lower end. They are made up of two sizes namely, one of 2 cm and the other of 3 cm and are divided into, , Construction: Draughtsman Civil - (NSQF Level - 5): Related Theory for Exercise 2.1.41, , Copyright Free under CC BY Licence

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equal pairs, each 0.2 m long. In order to make them visible, at a distance they are painted alternatively black or white, and red and white or red, white and black successively., When they are at a considerable distance red and white, or white and yellow flag about 25 cm square should be, fastened at the top., 3 Ranging poles, The ranging poles are similar to the ranging rods. But, are of heavier section. They vary in length from 4-10 cm, or more and are used in the case of very long line., Chain Surveying, Land Surveying: Land surveys are made for one or more, of the following purposes:, I, , To secure data for exact description of the boundaries, of a piece of land (or tract)., , II To determine its area., III To secure the necessary data for making a plan., IV To re-establish the boundaries of a piece of a land, which has been previously surveyed, and, , the lengths of its sides alone. The exact arrangement of, triangles to be adopted depends upon the shape and, configuration of the ground, and the natural obstacles, met with. If a point is located by the intersection of two, arcs, its displacement due to errors in the radii is a, minimum if the arcs intersect at 90°.The three sides of a, triangle being equally liable to error, each of the three, angles of a triangle should be nearly 60°. i.e. the triangle, should be equilateral. An equilateral triangle can, therefore, be more accurately plotted than an obtuseangled triangle. Hence the best shaped triangle is, equilateral and it is desirable to approximate to this form, in order that distortion due to errors in measurement and, plotting should be minimum., The framework should, therefore, consist of triangles, which are as nearly equilateral as possible, such triangles, being known as well conditioned, or well-shaped. A, triangle is said to be well conditioned or well-proportioned, when it contains no angle smaller than 30° and no angle, greater than 120°. III - conditioned triangles (Fig 8) having, angles less than 30° or greater than 120° should always, be avoided. If however, they are unavoidable, great care, must be taken in changing and plotting., , V To divide a piece of land into a number of units., There are two general methods of land surveying, 1 Triangulation and, 2 Traversing, 1 Triangulation Survey: Triangulation is the basis of, trigonometrical or geodetical surveys. The term, triangulation when used without qualification, denotes a, system of surveying in which the sides of the various, triangles are computed from, i, , a single line measured directly, called the base line,, and, , ii the three angles of each triangle measured accurately, with a theodolite., Chain triangulation or chain surveying: It is the system, of surveying in which the sides of the various triangles, are measured directly in the field and no angular, measurements are taken. The simplest kind of surveying, is the chain surveying. It is most suitable when., I, , The ground is fairly level and open with simple details., , II Plans are required on a large scale such as those of, estates, fields, etc., , Chain and Compass Traversing:, In traverse, surveying the directions of survey lines are fixed by, angular measurements and not by forming a network of, triangles as is done in chain surveying., A traverse surveying is one in which the framework, consists of a series of connected lines, the lengths and, directions of which are measured with a chain or tape,, and with an angular instrument respectively. The routine, of chaining and offsetting is the same as in chain, surveying. The running of check lines is not necessary., A traverse may be classed as (a) closed, and (b) unclosed, or open., a Closed Traverse: A traverse is said to be closed when, a complete circuit is made, i.e. when it returns to the, starting point forming a closed polygon as in Fig 9., or, when it begins and ends at point whose positions on, plan are known The work may be checked and, “balanced”., , III The area is a small in extent., It is unsuitable for large areas, and areas crowded with, many details or difficult or wooded country. The principle, of a chain survey is triangulation. It consists of the, arrangement of framework of triangles since a triangle is, the only simple plane figure, which can be plotted from, Construction: Draughtsman Civil - (NSQF Level - 5): Related Theory for Exercise 2.1.41, , Copyright Free under CC BY Licence, , 7

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It is particularly suitable for locating the boundaries of, lakes, woods, etc. and for the survey of moderately, large areas., b Unclosed traverse or open traverse: A traverse is, said to be open or unclosed when it does not form a, closed polygon as shown in Fig 10. It consists of series, of lines extending in the same general direction and, not returning to the starting point. Similarly, it does not, start and end as points whose positions on plan are, known. It is most suitable for the survey of a long, narrow strip of country, e.g. the valley of river, the coast, line, a long measuring road, or railway, etc., , 1 The prismatic compass, and, 2 The surveying or surveyor’s compass., The former is a very valuable instrument and is commonly, used for rough surveys, where speed and not accuracy, is the main consideration., The prismatic compass: The prismatic compass shown, in Fig 12. consists of a circular box about 85 to 110 mm, in diameter in the centre of which is balanced a magnetic, needle on a hard steel pointed pivot 2. The needle which, is of broad form carries an aluminium ring graduated to, degrees and half degrees. The graduations start from, zero marked at the south end of the needle and run, clockwise so that 90° are marked at the west, 180° at the, north, and 270° at the east. The figures are written, inverted. Diametrically opposite are fixed to the box the, sighting vanes and the reflecting prism with a sighting, slit at the top., , Instruments for Measurement of Angles: In order to, plot a survey line on paper, its length and direction must, be known. The direction of survey line may be defined, either., i, , by the horizontal angle between the line and the line, adjacent to it, or, , ii by the angle called the bearing, between the fixed line, of reference called the meridian and the line., For measuring angles in survey work, the instruments, commonly used are, i, , The compass, and, , ii The thedolite. Sometimes a box sextant is also used., The compass does not measure the angle between two, lines directly, but measures the angle between the, magnetic meridian and the line, the theodolite, on the, other hand, measures the angle between two lines,, directly, and also the bearing of the line., , The sighting (or object) vane consist of a lunged metal, frame in the center of which stretched a vertical horse, hair fine silk thread, or fine. When the instrument is not in, use or when it is being carried from point to point, the, , a magnetic needle (Fig 11), , sighting vane is folded on the glass lid which covers the, top of the box. It presses against a lifting pin which lifts, the needle off the pivot and holds it against the glass led,, thus preventing undue wear of the pivot point. To damp, the oscillations of the needle when about to take a reading, and to bring it to rest quickly, a light spring is fitted inside, the box., , b a graduated circle, , It can be brought into contact with the edge of the ring by, gently pressing inwards a knob or brake pin placed at the, base of the object vane. By means of the reflecting prism, which can be adjusted to the eye sight of the observer by, raising or lowering the frame carrying it by means of the, stud the graduations on the right below, being reflected, from the hypotenuse side of the prism to the eye can be, read. The faces of the prism both horizontal and vertical, being convex, the graduations are magnified. When not, , Compass: The compass consists essentially of, , c a line of sight, There are two forms of compass in common use, , 8, , Construction: Draughtsman Civil - (NSQF Level - 5): Related Theory for Exercise 2.1.41, , Copyright Free under CC BY Licence

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in use, the prism can be folded the edge of the box and is, held by the hinged strap. The top of the box is covered, with a glass lid so that the graduations on the ring may, be visible. It also protects the instrument from dust. A, metal cover fits over the glass lid and the sighting vane, when not in use. Sometimes the sighting vane is provided, with a lunged mirror which can be placed upwards or, down wards on the frame and can also be sided along it, as required. The mirror can be made to incline at any, angle so that objects too high or too low to be sighted, directly can be sighted by reflection. Dark glasses are, sometimes provided. They are interposed into the line of, sight, when luminous objects are to be sighted or sun, observations are required., When the needle points north, the reading under the prism, should be zero. But since the prism is placed exactly, opposite the sight vane, the south end will be under the, prism. Consequently, the zero graduation of the ring must, be placed at the south end of the needle. By this means, bearings are obtained clockwise from north., The prismatic compass is used for surveys in wooded, country, rough traverse, filling in details, preliminary survey, for road military purposes such as sketching and night, marching, etc. It is unreliable in places abounding in, magnetic rock or iron ore. It is less accurate than a, theodolite., , a magnetic bearing of the line, or simply a bearing of the, line., Arbitrary Meridian: For small surveys any convenient, direction may be taken as a meridian. It is usually the, direction from a survey station to some well-defined, permanent object, or the first line of survey. The angle, between this meridian and a line is known as an arbitrary, or assumed bearing of the line., Designation of bearings: There are two systems of, notation commonly used to express bearings viz., 1 The whole circle system and, 2 The quadrantal system, Whole Circle System: In this system the bearing of a, line is always measured clockwise from the north point, of the reference meridian towards the line right around, the circle. The angle thus measured is called whole circle, bearing (W.C.B). It may have any value between 0° to, 360°. Thus in Fig 13. the W.C.B of AP1 is 01, that AP2 is, 02, and so on. In this system the bearing is completely, specified by the angle, and the noting of the cardinal., , Bearing of lines: The bearing of a line as already states,, is the horizontal angle which the line makes with some, reference direction or meridian. The reference direction, employed in surveying may be., I, , A true meridian, , II A magnetic meridian, or, III An arbitrary or assumed meridian, The true meridian is usually employed in geodetic surveys,, while the magnetic meridian is used in plane surveys., True Meridians: The points of intersection of the earth’s, axis and the surface of the earth are known as the north, geographical pole and the south geographical pole. The, true or geographical meridian passing through a point on, the earth’s surface is the line in which the plane passing, through the given point, and the north and the south poles, intersects the surfaces of the earth. The direction of a, true meridian at a station in variable. The true meridians, through the various stations are not parallel, but converge, to the poles. However, for ordinary small surveys, they, are assumed to be parallel, to each other. The horizontal, angle between the true meridian and a line is called a, true bearing of the line. It is known as an azimuth., Magnetic Meridian: The direction indicated by a freely, suspended and properly balanced magnetic needle,, unaffected by local attractive forces is called the magnetic, meridian or the magnetic north and south line. The angle, which a line makes with the magnetic meridian is called, , Quadrantal System: In this system the bearing of a line, is measured clockwise or counter clockwise from the, north point or the south point whichever is nearer the, line, towards the east or west. It is, therefore absolutely, necessary to state the point from which the angle is, measured and also the direction in which it is measured., , Construction: Draughtsman Civil - (NSQF Level - 5): Related Theory for Exercise 2.1.41, , Copyright Free under CC BY Licence, , 9

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The plane around a station is divided into four quadrants, by the two lines at right angles to each other, of which, one is the north and south line and the other the east,, and west line. The letters N (north), S (south), E (east), and W (west) are used to show the quadrants. Thus in, Fig 13. the first quadrant is denoted by the letters. N.E.,, the second one by the letters S.E., the third one by the, letters S.W., and the fourth one by the letters N.W. In this, system the bearing is reckoned from 0° to 90° in each, quadrant. The quadrant bearing, therefore, never, exceeds 90°. There are two notations in which the bearing, of line is expressed. In the first notation the letters showing, the quadrant in which the line falls are put after the, numerical value of the angle. Thus the bearing of AP1, is, θ1 , N.E; that of AP2, θ 2, S.E; and so on., , (F.B) while its bearing in the opposite direction is known, as the back or reverse bearing (B.B), The end of the line at which the bearing is taken is, indicated by the order in which the line is lettered (i.e., given first) Thus in the above Fig 14. The bearing from A, to B is the fore bearing of the line AB, and that from B to, A is the back bearing of the line AB, or the bearing of the, BA. It will be noticed here that the fore and back bearings, of a line differ exactly by 180°. In the whole circle bearing, system the back bearing of a line may be obtained from, the fore bearing by the following rule., , In the second notation which is more commonly used,, the numerical value of the bearing is preceded by the, letter N or S and followed by the letter E or W. Thus the, bearing of AP3 is S θ 3 W; that of AP4 No θ 4W. and so on., It must be remembered that the quadrant bearings are, never reckoned from the east and west line. They are, often called the reduced bearings. The quadrant system, is an advantages when findng the values of the, trignometrical functions from the logarithems tables but, the disadvantages of the systems are:, Case, , W.C.B, between, , Rule of R.B, , I, , 0° and 90°, , = W.C.B, , NE, , II, , 90° AND 180°, , = 180 - W.C.B, , S.E, , III, , 180° AND 270° = W.C.B – 180, , S.W, , IV, , 270° AND 360° = 360 - W.C.B, , N.W, , I, , Quardrant, , The bearing is of no value, if either of the letters, showing the quadrant is omitted, and, , ii The noting of cardinal points is inconvenient, and may, cause mistakes., , Back bearing = Fore bearing ± 180° .............. (1), Use plus sign, if the given fore bearing is less than 180°, and minus sign, if it exceeds 180°., In the quadrant system the fore and back bearings are, numerically equal but with opposite letters. The back, bearing of a line may, therefore, be obtained by simply, substituting N. for, S or S. for N. and E, for W. or W. for E., thus, if the fore bearing of a line CD is N. 40°25’ E, the, back, bearing of CD is S. 40°25’ W., Examples on bearings, Examples 1:, , The bearings observed with a surveyor’s compass are, quadrantal bearings., Reduced bearings: When the whole circle bearing of a, line exceeded 90 ° , it must be reduced to the, corresponding angle less than 90°, which has the same, numerical values of the trigonometrical functions. This, angle is known as the reduced bearing (R.B). To obtain, the reduced bearings from the whole circle bearings of, lines, the following table may be referred to:, , i, , ii 132° 12’, iii 236° 37’, iv 334° 52’, Using the rule for R.B. we have, i, , Fore and back bearings, Every line has two bearings one observed at each end of, the line. The bearing of a line in the direction of the, progress of survey is called the fore or forward bearing, 10, , 68° 32’, , W.C.B = 68° 32’, ∴ Quadrant bearing = N. 68° 32’ E, , Construction: Draughtsman Civil - (NSQF Level - 5): Related Theory for Exercise 2.1.41, , Copyright Free under CC BY Licence

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Example 3: The following are the observed fore bearings, of the line., , ii W.C.B = 132° 12’, ∴ Quadrant bearing, , = 180° - W.C.B, = 180° - 132° 12’, = 47° 48’ S.E, = S. 47° 48’ E, , AB, 38° 14’, BC,142° 18’, CD, 208° 37’, DE, 318° 26’, , iii W.C.B = 236° 37’, ∴ Quadrant bearing, , = W.C.B = 180°, = 236° 37’ - 180°, , Find their back bearings., By the use of rule 1, we get,, , = 56° - 37’ S.W, , F.B. of AB, , = 38° 14’, , = S 56° - 37’ W, , ∴ B.B of AB, , = 38°14’+ 180°, , = 218°14’, , iv W.C.B = 334° 52’, ∴ Quadrant bearing, , = 360°, , F.B of BC, , = 142° 18’, , W.C.B, , = 360° - W.C.B, , ∴ B.B of BC, , = 142° 18’ + 180°, , = 360° - 334° 52’, , = 322° 18’, , = 25° - 8’ N.W, = N 25° - 8’ W, Example 2: Convert the following reduced bearings to, whole circle bearing, , F.B of CD, , = 208° 37’, , ∴ B.B of CD, , = 208° 37’ - 180°, , = 28° 37’, , a N. 36° 16’ E, , F.B of DE, , = 318° 26’, , b S. 28° 14’ E, , ∴ B.B of DE, , = 318° 26’ - 180°, , c S. 47° 26’ W, , = 138° 26’, , d N. 58° 24’ W, a R.B, ∴ W.C.B, b R.B, ∴ W.C.B, , Example 4: The fore bearings of the lines are as follows:, = N.36° 16’ E, , AB, N. 32° 12’ E, , = R.B = 36° - 16’, , BC,S. 43° 18’ E, , = S. 28° 14’ E, , CD, S. 26° 30’ W, , = 180° - R.B, , DE, N. 65° 24’ W, , = 180° - 28° 14’ = 151° 46’, = S. 47° 26’ W, , c R.B, ∴ W.C.B, , = 180° + R.B, = 180° + 47° 26’ = 227° 26’, = N. 58° 24’ W, , d R.B, ∴ W.C.B, , = 360° - R.B, = 360° - 58° 24’ = 301° 36’, , Find their back bearings., When bearings are expressed on the quadrant system,, the back bearing of the line is numerically equal to its, fore bearings but with opposite letters. Therfore, we have,, F.B of AB, , = N. 32° 12’ E, , ∴ B.B of AB, , = S. 32° 12’ W, , F.B of BC, ∴ B.B of BC, , = S. 43° 18’ E, = N. 43° 18’ W, , Construction: Draughtsman Civil - (NSQF Level - 5): Related Theory for Exercise 2.1.41, , Copyright Free under CC BY Licence, , 11

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F.B of CD, ∴ B.B of CD, F.B of DE, ∴ B.B of DE, , = S. 26° 30’ W, , Pantagraph (Fig 16), , = N. 26° 30’ E, = N. 65° 24’ W, = S. 65° 24’ E, , Planimeter (Fig 15), , The pantagraph, an apparatus for making enlarged or, reduced drawings, first appeared in the early seventeenth, century, its invention credited to the Jesuit mathematician, and astronomer Christoph Scheiner (1575 -1650). The, CCA (Canadian Centre for Architecture) version, shown, here, was manufactured in England in the early nineteenth, century. It is part of a collection of some 40 individual and, sets of drawing instruments and aids of the CCA., The planimeter is simple instrument for the precise, measurement of areas of plane figures of any shape. To, measure an area, it is only necessary to trace the outline, of the figure in a clockwise direction with the centre point, (with in the ring) of the tracing lens and to read off the, result on the scales. (Fig 15), The Planimeter consists of 3 separate parts; the tracing, arm to which is attached the roller housing the pole arm, and the pole plate. The three parts are packed separately, in the case. The pole arm is a simple beam. On each, end is fixed a ball, one for fitting into the roller housing,, the other into the pole plate. The roller housing rests on, three supports; the tracing lens, the measuring roller and, a supporting ball., , The lacquered brass instrument is engraved with the, maker’s name and with standard ratios and scales to, assist in its functioning. The pantagraph includes a brass, disc fitted with sharp points on its underside to hold the, tool firmly to the drafting table, a stylus with which to trace, an existing drawing, and a pencil holder that also, accommodates a cup to hold a lead weight. Ivory wheels, permit the instrument to move smoothly. A fitted, mahogany case, lined with felt, protected the instrument, within the office and during transport., , Introduction and terms used, Objectives : At the end of this lesson you shall be able to, • define levelling, • describe the uses of levelling, • explain the various terms used in levelling., Uses: Levelling is usually carried out for the following, purposes:, , Introduction, It is the art of determining the relative heights of various, points on the surface of the earth. levelling is the branch, of surveying which deals with the measurements in the, vertical plane., , 12, , 1 To prepare contour map for fixing sites for reservoirs,, dams, barrages etc. and to fix the alignments of road,, railways, irrigation canals etc., , Construction: Draughtsman Civil - (NSQF Level - 5): Related Theory for Exercise 2.1.41, , Copyright Free under CC BY Licence

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2 To determine the altitudes of different important points, on a hill or to know the reduced levels of different points, on or below the surface of the earth., , 9 Elevation: The elevation of any point is it vertical, height or depth above or below the datum surface. It, is also otherwise known as the Reduced Level (R.L)., , 3 To prepare a longitudinal section and cross section of, a project (roads, railways, irrigation canals, etc,) in, order to determine the volume of earth work., , 10 Difference in Elevation: The difference in Elevation, is the vertical distance between the level surfaces, passing through the two points., , 4 To prepare a layout map for water supplying, sanitary, or drainage schemes., , 11 Bench Mark (B.M): A bench mark is the reference, point of known elevation., 12 Line of collimation: A line of collimation is the line, joining the intersection of cross-hairs in the diaphragm, and the optical centre of the object glass, and its, continuation. It is also otherwise known as line of sight., , Terms Used (Fig 1), , 13 Axis of the telescope: An axis of the telescope is the, line joining the optical cente of the object glass and, the centre of the eye piece. In general, the axis of, telescope and the line of collimation coincides each, other in case of a perfect levelling instrument., 14 Bubble line: A bubble line is an imaginary line, tangential to the longitudinal curve of the bubble tube, at its middle point. It is horizontal when the bubble is, centered. (Fig 2), , 1 Level Surface: The Surface which is normal to the, direction of gravity at all points is known as level, surface. All the points on level surface is equidistant, from the centre of the earth and so it is curved surface., It is perpendicular to the plumb line all points Eg.,, surface of a still lake., 2 Level line: A line lying on a level surface is a level line., This is normal to plumb line at all points., 3 Horizontal Surface: A horizontal surface is the one, which is tangential to the level surface at any point., 4 Horizontal line: A horizontal line is the line lying in a, horizontal surface. It is a straight line tangential to the, level line., 5 Vertical line: A vertical line is a line perpendicular to, the level line. It is also otherwise known as plumb, line as it passes through the centre of the earth., 6 Vertical plane: A vertical plane is the one, which, consists of many number of vertical lines., 7 Vertical angle: Vertical angle is an angle measured, between a line and a horizontal line in a vertical plane, 8 Datum surface: Datum surface is an imaginary or, any arbitarily assumed level surface, from which, vertical distances of the points above or below the, surface are measured. The datum surface adopted, by the Great trigonometrical survey (G.T.S) department, of India is the mean sea level at Mumbai which is, taken as zero., Mean Sea level (M.S.L) is the average height of the, sea for all stages of tides. It is the average of hourly, tides for a long period of 19 years., , 15 Vertical Axis: A vertical axis through which the, telescope is revolving in the horizontal plane i.e, the, axis of rotation. Normally vertical axis is the plumb, line from the centre of the instrument when it is, levelled., 16 Back Sight (B.S): Back sight is the first sight taken, on a levelling staff held over a point or known elevation, (i.e. B.M. or C.P) after the instrument is setup and, levelled. It gives the amount of height by which the, line of collimation is above or below the point, and, enables the surveyor to calculate the R.L of line of, collimation. It is also known as positive or plus sight, as this reading is added with the R.L of the point on, which it is taken to obtain the R.L of line collimation., (Except in the case of Inverted Staff readings)., 17 Fore Sight (F.S): Fore sight is the last sight taken on, a levelling staff held over a point of unknown elevation, (C.P) before shifting the instrument. It gives the, amount of height by which the point is above or below, the line of collimation, and enables the surveyor to, calculate the R.L. of the point. It is also known as, ‘negative’ or minus sight’ as this reading is subtracted, from R.L. of line of collimation to obtain the R.L. of the, point., 18 Intermediate Sight (IS): Intermediate sight is the sight, taken between the back sight and fore sight on levelling, staff held over a point of unknown elevations. It is, , Construction: Draughtsman Civil - (NSQF Level - 5): Related Theory for Exercise 2.1.41, , Copyright Free under CC BY Licence, , 13

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also known as ‘minus or negative sight’ as this reading, are separated from R.L of line of collimation., 19 Change point (CP): A change point is the one which, makes the instrument to shift from one point to another., It is a point on which both the fore sight and back, sight readings are taken from the previous and new, positions of instrument. Stable and well defined objects, are selected as change point. A bench mark may, also be taken as a change point. It is also otherwise, known as turning point., , 2 Permanent bench mark, These are bench marks established in between the GTS, bench marks by various government department like, PWD and other engineering agencies, on some, permanent points, such as kilomatre stone, corners of, plinths of building, top of parapets of bridge etc., 3 Arbitrary Bench Mark (Fig 3), , 20 Height of Instrument (H.I): Height of instrument is, the elevation of reduced level of line of collimation, when the instrument is perfectly levelled. It is also, otherwise known as ‘Height of collimation’. (Not the, height of telescope from the ground)., Types of bench marks, , 1 G.T.S Bench Mark, , For small levelling work, any convenient well defined point, may be assumed as a bench mark and elevations of other, points are determined with reference to this bench mark., Such bench mark is known as arbitrary or assumed bench, mark., , 2 Permanent Bench Mark, , 4 Temporary Bench Mark, , 3 Temporary bench Mark, , The bench marks, which are established for short, duration, such as at the end of a day’s work, are called, temporary bench marks. The work should be resumed, from these bench marks., , Depending upon the permanency and the precision,, bench marks may be classified into four categories as, follows:, , 4 Arbitrary bench Mark, 1 GTS (Great Trignometrical Survey) bench mark, The bench marks established by the survey of india, department, at an interval of 100 km all over the country, with respect to the mean sea level at Mumbai as datum, is known as GTS bench mark. Their positions and, reduced levels are shown on GTS maps and catalogues., , 14, , Construction: Draughtsman Civil - (NSQF Level - 5): Related Theory for Exercise 2.1.41, , Copyright Free under CC BY Licence

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Construction, Related Theory for Exercise 2.1.42 - 44, Draughtsman Civil - Chain surveying, Introduction about chain survey instruments, Objectives : At the end of this lesson you shall be able to, • state the construction and uses of the following chain survey instruments., -, , Ranging Rod, , -, , Offset Rod, , -, , Arrows, , -, , Wooden Peg, , -, , Plumb bob, , -, , Measuring Tapes, , -, , If is also used for fixing intermediate points in ranging., , Offset rod (Fig 2), , Ranging Rod (Fig 1), , -, , It is wooden/steel pipe of 2m or 3 m in length with, 3 cm in diameter., , -, , It is painted in red and white or black and white in, 20 cm band width., , -, , Bottom of rod is fixed with a sharp metal shoe for, fixing on ground, , -, , Flag is fixed on the top for visibility when it is more, than 200m in distance., , -, , It is used for making the position of station in chaining., , -, , It is similar to the ranging rod with a hook at the top., , - It is used for pulling or pushing the chain through hedges, and other obstruction., -, , It is also used for aligning offset line and measuring, short offset., , Arrows, -, , It is made up of 4mm steel wire and 40cm long as, shown in Fig 3. It is pointed at one end for inserting, 15, , Copyright Free under CC BY Licence

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into the ground. Another end bent into a ring for easy, handling. Each metric chain shall accompanied with, 10 arrows as shown in Fig 4., , Plumb bob (Fig 6), , While chaining along a sloping ground, it is used to, transfer the points on the ground. It is also used as a, centering aid in Theodolite, compass and plane table., Measuring tape, This is the instrument used for measuring distances., They are made of, -, , It is used to make the ends of each chain during the, process of chaining., , Wooden peg (Fig 5), These are 15cm in length and tapered at one end. It is, used to drive on the ground to mark the position of, stations., , 1 Cloth or linen tape: It is 12 to 15 mm wide and is, made of linen cloth. It is available in length of 10m,, 20 m and 30m. At the end of this tape provided with, brass handle which is included in the total lengths of, the tape., It is easily affected by dampness., It is used for taking measurement such as offsets., 2 Metallic tape, 3 Steel tape, , 16, , Construction: Draughtsman Civil - (NSQF Level - 5): Related Theory for Exercise 2.1.42 - 44, , Copyright Free under CC BY Licence

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− Each metre length is divided into 10 parts (decimetre), , 4 Invar tape, 5 Fibre or Plastic tape, 6 Steel band, , and each part is further subdivided into 10 parts, (centimetre), , − The other side of the tape is graduated with feet and, , Metallic Tape (Fig 7), , − It is made up of linen and reinforced with fine brass or, copper wire. It is covered in a leather case with winding device., , − It is available in 15m (50ft) and 30m (100ft)., , inches., , − It is commonly used for taking offsets in chain surveying., , − This cannot be used for taking very accurate measurement., , − It is used for taking measurements and also used for, , Steel Tape (Fig 8), , − It is made of steel ribbon varying in width 6mm to, , testing chain lengths., , 16mm and available in 1m, 3m, 5m, 10m, 15m, 30m, and 50m in length., , − Each meter is divided into 200 parts. (Each being 5mm), First 10 cm length of the tape is divided into, millimeter., , Steel Band, 1 It is used for accurate work, 2 It is lighter weight and easier to handle than the chain., 3 It is 20m or 30m long., 4 It is made from ribbon of steel 16mm wide., , 8 It is divided by brass studs at 0.2m and numbered at, every 1m in the first portion and the last link is sub, divided into cm and mm., 9 The graduations are etched as metres, decimeters, and centimeters on one side and 0.2m links on the, other side. Brass tallies are fixed at every 5 in length., , 5 The brass handles are provided at the ends of the, chain with swivel joint., 6 It is wound on an open steel cross or a metal reel in a, closed case., 7 The graduations are worked in two ways., Construction: Draughtsman Civil - (NSQF Level - 5): Related Theory for Exercise 2.1.42 - 44, , Copyright Free under CC BY Licence, , 17

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Invar Tape, , − It has very low co-efficient of thermal expansion., , − It is made of an alloy steel (64%) and nickel (36%), , − It is only used for highest precision measurement like, , and available in 30m, 50m and 100m lengths., , baseline in triangulation work., , − It is easily kinked and broken, so care should be taken, while taking measurements., , Testing of metric chain (20m/30m), Objectives : At the end of this lesson you shall be able to, • state the necessity of checking the chain, • state the methods of testing, • list out the errors in the chain, • state the limits of error in chain, • explain the adjust the chain, • state Indian optical square., Necessity of checking the chain, The length of chain changes due to wear and tear, mud, sticking and change in temperature., , Therefore, it becomes necessary to check the chain, before commencing the survey work. Before testing the, chain, the bentup links should be straightened and mud, should be removed from the joints., , The length of chain increases due to, , Method of testing chain, , – Stretching of links and joints., , – Following are the method of testing a chain (Fig 1), , – Opening out of the rings., – Wear of wearing surfaces., , − By comparing it with a chain standard or with a test, gauge., , – Rough handling in pulling it through hedges and, fences., , – By comparing the chain with the levelling staff laid, down successively., , The length of chain decrease due to bending of the links, and mud-sticking., , – By comparing the chain with the steel tape reserved, specially for this purpose, , 18, , Construction: Draughtsman Civil - (NSQF Level - 5): Related Theory for Exercise 2.1.42 - 44, , Copyright Free under CC BY Licence

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measured with tension of 8 kg and checked against a, certified steel tape which has been standardized at 20°C., , Errors in Chain, Errors in Chain are:, 1 Instrumental Error: They occur due to faulty, adjustment of devices such as chain may be too long, or too short etc., 2 Natural Errors: They arise due to variation of, temperature., 3 Personal Errors: They are due to chain not being, straight., Mistakes in Chaining, , The overall length of chain should be within the following, limits., 20m chain: ± 5 mm, 30m Chain: ± 8mm, Adjusting the Chain, I, , If the chain is found to increase in length than the, standard length, it may be adjusted., i, , Mistakes are generally done by in experienced chainman., These can be avoided by careful working. Following are, the common mistakes made in the field., I, , Miscounting the chain length: This is the most, serious mistake and occurs due to wrong counting or, due to loss of arrow., , II Displacement of Arrows: If an arrow is displaced, it, may not be replaced correctly. To avoid this mistake,, the end of the chain length should be marked both by, scratching a cross on the ground and fixing an arrow., , by closing up the joints of the opened out rings., , ii by Hammering back to the shape, of the flattened, out rings., iii by replacing some of the larger rings by smaller, rings., iv by removing some of the rings., v by adjusting links at the handle., II If the chain is found to decrease in length than the, standard length, it may be corrected., , III Misreading: It happens due to reading from the wrong, end of the chain. It can be avoided by carefully noticing, the position of the central tag., , i, , Limits of Error in Chain, , iii by inserting the new rings as required, , As per Indian standard specifications every meter length, of chain should be accurate to within ± 2mm when, , by straightening the bent up links., , ii by replacing some of the smaller rings by larger, ones., , iv by adjusting the links at the handle., , Measurement of distance by chain and chaining, Objectives : At the end of this lesson you shall be able to, • state chaining and chaining a line, • state unfolding the chain, • describe the reading the chain, • state folding the chain, • calculate the errors in chaining., Chaining:, , – It is composed of 4mm dia. Mild steel wire., , Definition: The operation of measuring a distance, between two points with the help of a chain or tape is, called chaining., , – Each link having 20 cm in length and connected, together by means of three circular rings to give, flexibility to the chain., , For ordinary works chain is used for measuring the, distances but where great accuracy is required, a steel, tape is invariably used., , – Length of link is the distance between the centres of, two consecutive middle rings., , Identification and Construction of metric Chain, , – Brass handles are provided at the ends of the chain, with swivel joints so that the chain can be turned round, without twisting., , _ It is a measuring instrument consists of, , – The outside of the handle is the zero point or the end, point of the chain., , i, , 100 links in 20m chain and (Fig 1), , ii 150 links in 30m chain (Fig 2), , – The length of the chain is the distance from outside of, one handle to the outside of the other handle., , Construction: Draughtsman Civil - (NSQF Level - 5): Related Theory for Exercise 2.1.42 - 44, , Copyright Free under CC BY Licence, , 19

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– End links also includes the length of the handle., , Leader, , Follower, , – Chain has brass rings at every one metre length., – Brass tallies are provided at every 5m length as shown, in (Fig 1 & 2), Chaining a Line, For a chaining operation two chain men are required., – The chain man at the forward end of the chain is called, leader and other chain man at the rear end is called a, follower., , To drag the chain forward. To direct the leader to be, in line with the ranging rod, at the end stations., To insert an arrow at the To carry the rear end of the, end of every chain., chain ensurig that it is, dragged above the, ground., To obey the instructions of To pick up the arrows, inserted by the leader., the follower, , – The duties of leader and follower are tabulated under:, Unfolding the chain, Before commencing the chain, the surveying or follower, keeping both handles of the chain in his left hand, spread, the chain with the forward direction with the right hand., The leader taking handle of the chain in his hand and, moves towards till the chain is fully extended., , 20, , Construction: Draughtsman Civil - (NSQF Level - 5): Related Theory for Exercise 2.1.42 - 44, , Copyright Free under CC BY Licence

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Reading the chain, , Example, , -, , Problem 1, , -, , The chain is marked by tallies at every 5m length and, small brass rings at every 1m length without having, difficulty in reading the chain., In taking measurements, observe the tag immediately, before the end point, which is being measured to and, count the number of brass rings and links from it in, the forward direction to the end point., , The distance between two points measured by 20m chain, was recorded as 720m. It was afterwards found that the, chain used was 4cm too long. What was the true distance, between the points?, Solution, , -, , In reading near the centre of the chain care must be, taken to see the position of the central tag., , ⎛ L' ⎞, True distance = Measure distance × ⎜, ⎟, ⎝ L⎠, , -, , To get the total distance add the above fractional part, of the chain with number of full chain, it distances, exceeds more than one chain length., , Measured distance, , Folding the Chain, After the field work the chain should be folded into a, bundle. The chain is folded by taking central two lines in, the left hand until the handle of links is formed and lied, up with a strip of leather., , =, , 720 m, , Chain, , =, , 20m, , Error, , =, , (+) 4 cm, , ∴ L’ = = 20 +, , 4, 100, , =, , 20.04m, L=20m, , True distance = 720 ×, , Error in length due to in correct chain, , 3, , 20.04, 20, , = 721.44m, , Correct or True distance =, , Problem 2, , Incorrect or measured distance x, , A field was surveyed by a chain and the area was found, to be 127.34 hectares. If the chain used in the, measurement was 0.8% too long. What is the correct, area of the field?, Solution, , (or), True distance = Measured distance ×, where L, L’, , ', L, , Chain used, , L, , True area, , = 100 units, , ⎛ L' ⎞, = Measured area × ⎜ ⎟, ⎝L⎠, , 2, , L = 100 + 0.8 = 100.8 units, L = 100 units, , = True length of chain or tape, =Incorrect length of chain or tape, , True area, , Error in area due to incorrect chain, , ⎛ L' ⎞, ⎟, ⎝L⎠, , = 129.386 hectares, , 2, , Exercise, , True area = Measured area × ⎜, , 1 The length of a line, measured with a 30m chain was, found to be 4920m. If the chain was 0.3 link too short,, find the true length of the line., , Error in volume due to incorrect chain, , ⎛ L' ⎞, ⎟, True volume=Measured Volume = × ⎜, ⎝ L⎠, , =, , 3, , 2 A road actually 2660m long was found to be 2652m, when measured with a defective 30m chain. How, much correction does the chain need?, , Construction: Draughtsman Civil - (NSQF Level - 5): Related Theory for Exercise 2.1.42 - 44, , Copyright Free under CC BY Licence, , 21

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Construction, Draughtsman Civil - Chain surveying, , Related Theory for Exercise 2.1.45, , Knowledge of mouza map, Objective : At the end of this lesson you shall be able to, • describe above mouza., Mouza, In Bangladesh, Pakistan and parts of India a mouza (or, mauza) is a type of administrative district, corresponding, to a specific land area within which there may be one or, more settlements. Before the 20th century, the term, referred to a revenue collection unit in a pargana or, revenue district. As populations increased and villages, became more common and developed, the concept of, the mouza declined in importance. Today it has become, mostly synonymous with the gram or village. Most, censuses and voter lists for example, now use the name, of village rather than mouzas., , The term has a similar meaning in the Assam region of, India, where a mouza is a locality in a district or within a, large Assamese city. This terms should not be confused, with the terms Gaon (meaning village in Assamese, Hindi, and Urdu) In Assam, several villages typically form a, single mouza. The head of the mouza is known as a, mouzadar or mazumdar., Study the mouza map, Kolkatta mouza map (Fig 1), Koch bihar river map (Fig 2), , 22, , Copyright Free under CC BY Licence

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Construction: Draughtsman Civil - (NSQF Level - 5): Related Theory for Exercise 2.1.45, , Copyright Free under CC BY Licence, , 23

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24, , Construction: Draughtsman Civil - (NSQF Level - 5): Related Theory for Exercise 2.1.45, , Copyright Free under CC BY Licence

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Construction, Related Theory for Exercise 2.2.46, Draughtsman Civil - Compass surveying, Identification and Parts of instruments in compass survey, Objectives : At the end of this lesson you shall be able to, • state about traversing, • state types of compass, • name the prismatic compass and construction, • construction of survey’s compass., , Traversing, Traversing is that type of survey in which a number of, connected survey lines from the frame work and the, directions and lengths of the survey line are measured, with the help of an angle measuring instrument and a, tape respectively. When the lines form a circuit which, ends at the starting point is called closed traverse. Fig 1., If the circuit end else where it is said to be an open, transverse. (Fig 2), , Compass: A compass is a small instrument which, consists essentially of a magnetic needle, a graduated, circle and a line of sight. When the line of sight is directed, towards line, the magnetic needle points towards, magnetic meridian and the angle which the line makes, with the magnetic meridian is read at the graduated circle., The compass cannot measure the angle directly. If it is, desired to find out the angle between the two lines, firstly, their angles with the magnetic meridian are determined, separately and the difference of the two valves is found, which is equal to the angle between the lines., Types of Compass: The two forms of the compass, commonly used are:, , The prismatic compass: It is the most convenient, portable magnetic compass, which can either be used, as a hand instrument or can be fitted on a tripod. The, main parts of prismatic compass are shown in Fig 3., Construction (Fig3), , •, , The prismatic compass consists of cylindrical metal, box (1) of 8cm to 12 cm diameter in the centre of, which is a pivot (2) carrying a magnetic needle. (3), which is already attached to the graduated aluminium, ring (4) with the help of an agate cap (5), , •, , The ring is graduated to half a degree and is ready by, a reflecting prism (6) which is protected from dust,, moisture etc. by the prism cap (7), , •, , Diametrically opposite to the prism is the object vane, (8) hinged to the box side and carrying a horse hair, (9) with which an object is bisected., , •, , The eye is applied at the eye hole below the sighting, slit (10), , •, , The graduations on the ring can be observed directly, by the eye after they are reflected from the diagonal, of the prism., , 1 The prismatic compass, 2 The surveyors compass, , 25, , Copyright Free under CC BY Licence

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•, , The graduations can be made clearly visible by, adjusting the prism to the eye sight by the focusing, screw (11), , •, , Both the horizontal and vertical side faces of the prism, are made convex to give magnified readings., , •, , To prevent undue wear of the pivot ,point the object, vane is brought down on the face of the glass cover, (12) which presses against a lifting pin (13), , •, , The needle is then automatically lifted off the pivot by, the lifting lever (14), , •, , To damp the oscillations of the needle, before taking, a reading and bring it to rest quickly the light spring, break (15) attached to the inside of the box is brought, in contact with the edge of the ring by gently pressing, inward the brake pin (16), , •, , If the bearings of very high (or) very low objects are, taken the reflecting mirror (17) which slides on the, object vane is tilted and image is bisected by the horse, hair., , •, , A pair of sun glasses (18) shall have to be inter, proposed between the slit and colored vane when the, sun or luminous of objects is to be bisected., , •, , A metal cover fits over the glass cover as well as the, object vane when the compass is not in use., , •, , In the prismatic compass (Fig 4a) graduations are, marked on the ring in a clockwise direction with 0 or, 360 at south end of the needle., , •, , So that 90 is marked at the west 180 at the North and, 270 at the east., , •, , The figures are written upside down as in Fig (4b), , The bearing shows 330° at the observer’s end under the, prism (ie at the south end) (Fig 5), , Surveyors Compass: It is similar to prismatic compass, except with a following few modification (Fig 6), , – The graduated ring is directly attached to the circular, box and not with the magnetic needle., , – The magnetic needle floats freely over the pivot., – No prism is attached to the eye vane and it is having a, narrow vertical slit., – Readings are taken directly with naked eye against, the north end of the needle., – The right is graduated in quadranted system of having, 0° at north and south ends, 90ˆ at East and west, ends. Fig 6a shows when the line of sight towards ‘B’, and the bearing is N 30° E., Bearing of a line: It is the horizontal angle which a line, make with some reference direction also known as, meridian. The reference direction may be any of the, following (Fig.7), •, , 26, , The greatest advantages of prismatic compass is that, both sighting the object as well as reading circle can, be done simultaneously without changing the position, of the eyes., , – True meridian, – Magnetic meridian, – An assumed meridian, , Construction: Draughtsman Civil - (NSQF Level - 5): Related Theory for Exercise 2.2.46, , Copyright Free under CC BY Licence

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Comparison between prismatic compass and surveyors compass, No, , Item, , Prismatic compass, , 1, , Magnetic needle, , The needle is broad type and needle, does not act as index., , 2, , Graduated ring, , The graduated ring is attached with, the needle. The ring does not rotate, along with the line of sight., The graduations are in whole circle, bearing system, having 0° at south, end 90°at west, 180° at North and, 270° at East., , Survryor’s compass, The needle is of edge bar type of, needle and acts as the index also., The graduated ring is attached to the, box and not the needle. The ring rotates along with the line of sight., The graduations are in Quadrantal, bearing system having 0°at North, system having 0°at North and South,, 90° at East and West. East and west, are interchanged., , The graduations engraved are inverted., , The graduations engraved are erect., , 3, , Sighting vane, , The object vane consists of metal, vane with a vertical hair., , The object vane consists of a metal, vane with a vertical hair., , 4, , Reading, , The reading taken with the help of a, prism provided with the eye vane., , The reading is taken by directly seeing through the top of the glass., , Sighting and reading can be done, simultaneously from one position of, the observer., , Sighting and reading cannot be done, simultaneously from one position of, the observer., , It is used with or without Tripod., , It cannot be used without a Tripod, , 5, , Tripod, , An assumed or Arbitary meridian: Arbitary meridian is, any convenient direction towards a permanent and, prominent mark or signal such as a church spire or top of, a chimney. Such meridians are used to determine the, relative positions of lines in a small area., Arbitary Bearings: Arbitary bearings of a line is the, horizontal angle which it makes with any arbitrary meridian, passing through the one of the extremities or the horizontal, angle between a line and this arbitrary meridian is called, arbitrary bearing of the line., True Meridian: The meridian of a place is a direction, indicated by an imaginary circle passing round the earth, through that place and the two north and south poles., True Bearing: The horizontal angle between a line and, the true meridian is called true bearings of the line. It is, also called as azimuth., , Designation of Bearings: The bearings are expressed, in the following two ways., – Whole circle bearings., – Quadrantal bearings., , Magnetic Meridian: The direction indicated by a freely, suspended and properly balanced magnetic needle, unaffected by local attractive forces is called the magnetic, meridian., , Whole Circle bearing (W.C.B): In this system, the, bearings of a line, is measured from the magnetic north, in clockwise direction. The value of the bearing thus varies, from 0° to 360°. The prismatic compass measures the, bearings of lines in the whole circle system., , Magnetic Bearings: The horizontal angle which a line, makes with this meridian is called magnetic bearings or, simply bearings of the line., , Referring Fig 8 the W.C.B of AB is θ1; of AC is θ1 and, AC is θ2; AD is θ3 and of AF is θ 4., , Construction: Draughtsman Civil - (NSQF Level - 5): Related Theory for Exercise 2.2.46, , Copyright Free under CC BY Licence, , 27

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trigonometrical function is known as reduced bearing, (R.B), i, , Referring Fig 8, W.C.B system, the conversion of, W.C.B into R.B can be expressed in the following table., Table 1, Line, , W.C.B, between, , Rule for R.B, , Quadrant, , AB, , 0° and90°, , R,B = W.C.B, , NE, , AC, , 90º and, 180º, 180º and, , R,B =180º W.C.B, R.B = W.C.B -, , SE, , 270º, , 180º, , 270º and, 360º, , R.B = 360º W.C.B, , AD, AF, The Quadrantal bearings: In this system, the bearings, of a line is measured east ward or westward from north, or south whichever is nearer. Thus both North and South, are used as reference meridians and the directions can, be either clockwise or anticlockwise depending upon the, position of the line. These bearings are observed by, surveyors compass., Referring Fig 9 the QB of the line AB is ∝ and it is written, as N∝ E, , SW, NW, , ii Referring Fig 9 the conversion of R.B into W.C.B can, be expressed in the following table., Table 2, Line, , R.B, , Rule for W.C.B, , W.C.B between, , AB, , NαE, , W.C.B = R.B, , 0 AND 90, , AC, , Sβ E, , W.C.B = 180- R.B, , 90 AND 180, , AD, , SθW, , W.C.B = 180+ R.B, , 180 AND 270, , AF, , N φW, , W.C.B = 360 - B, , 270 AND 360, , Fore Bearings and Back Bearings: Every line has two, bearings, observed one at each end of the line. The, bearing of a line taken in the progress of the survey or in, the forward direction is the fore or forward bearing (F.B), of the line. While its bearing taken in the reverse or, opposite direction is known as reverse or back bearing, (B.B), Whole Circle bearing system, Fig 10 shows. The bearing of line AB expressed in the, direction A to B is the F.B of AB., , The bearing of Line AC is band it is written as S β E., Similarly, the bearing of line AD and AF are written as S θ, W and N φ W, Conversion of Bearings from one system to other, system, Reduced bearing, When the whole circle bearings exceed 900 , then it is, to be converted or reduced to quadrantal bearing system, which has the same numerical values of the, 28, , Construction: Draughtsman Civil - (NSQF Level - 5): Related Theory for Exercise 2.2.46, , Copyright Free under CC BY Licence

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The bearing of line AB when recorded in the opposite, direction from B to A is BB (or) F.B of BA (Fig 11), , Solution, Applying the rules given in the table 1, i, , W.C.B, , = 12° 30’, , W.C.B, , = 12° 30 which is less than, 90°, , ∴ R.B, , = N 12° 30’ E (Fig 1), , In the whole circle system, the fore and back bearings of, a line differ exactly by 180°, , ∴B.B of a line = F. B ± 180° [ Equation 1], Use plus sign if the given F.B is less than 180°, and minus sign if it exceeds 180°, Quadrantal bearing system, , ii W.C.B, , = 160° 30’, , The W.C.B is within 90° to 180°, ∴ RB, , = 180° - W.C.B, =180° - 160° 30’, , In the quadrantal system F.B and B.B are numerically, equal but with opposite cardinal points. B.B of aline may,, therefore be obtained by simply substituting N for S or S, for N; and E for W or W for E in its fore bearings (Fig 12)., , = S19° 30’ E (Fig 2), , iii W.C.B, , = 210° 30’, , The W.C.B is within 180° to 270°, ∴ RB, Supposing F.B of a line is n 30°E then its B.B, is equal to S 30° W, , = W.C.B - 180°, = 210° 30’ – 180’, = S 30° 30’ W (Fig 3), , Example, Problems on conversion of bearing, a Convert the following W.C.B to quadrantal bearings., i, , 12° 30’, , ii 160° 30’, iii 210° 30’, iv 285° 30’, , Construction: Draughtsman Civil - (NSQF Level - 5): Related Theory for Exercise 2.2.46, , Copyright Free under CC BY Licence, , 29

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iv W.C.B, , = 285° 30’, , The W.C.B is within 270° to 360°, ∴ R.B, , W.C.B, , = S 36° 30’W, = 180° + Q.B, , = 360° - W.C.B, , = 180° + 36° 30’, , = N 74° 30’ W (Fig 4), , = 216° 30’ (Fig 3), , b Convert the following quadranted bearings to whole, circle bearings., i, , iii Q.B, , iv Q.B, W.C.B, , = N 85° 30’W, = 360º - 85º 30’, = 274º 30’ (Fig 4), , N 30° 30’ E, , ii S 70° 30’, iii S 36° 30W, iv N 85° 30W, Solution, Applying the rules given in Table 2, i, , Q.B, , = N30° 30’E, , W.C.B, , = RB = 30° 30’ (Fig 1), Exercise, 1 Convert the following W.C.B to R.B, a 87º 30’, b 120º 30’, c 210º 00, d 266º 30’, e 310º 30, , ii Q.B, W.C.B, , = S 70° 30’E, =180° - R.B, = 180° - 70° 30’, = 109° 30’ (Fig 2), , f, , 359º 30’, , 2 Convert the following R.B to W.C.B, a N 46º 30’ E, b S 20º 30’ E, c S 10º 30’ W, d N 50º 30’ W, Example, Find back bearings of the following observed fore bearings, of lines AB 63º 30’, BC 112º 30, CD 203º 30; DE 320º, 30’, , 30, , Construction: Draughtsman Civil - (NSQF Level - 5): Related Theory for Exercise 2.2.46, , Copyright Free under CC BY Licence

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Solution, From the equation (1), ∴ B.B = F.B ± 180º, Using + sign when F.B is less than 180º and sign more than 180º, i, , F.B of AB, , = 63º 30 (Fig 1), , ∴ B.B of AB, , = F.B of AB + 180º, = F.B of AB + 180º, = 63º 30 + 180º, = 243º 30’, , B.B of AB, ii F.B of BC, , = 243º 30’, = 112º 30’ (Fig 2), , Example, The fore bearing of the lines are as follows:, AB: N 32º 30E, BC: S 43º 30 E, CD: S 26º 30W, DE: N 65º 35, W, Find their back bearings, Solution, , B.B of BC, , = F. B of BC + 180°, , = 292º 30’, , When bearings are expressed on the quadrantal systems,, the back bearings of a line is numerically equal to its fore, bearings but with opposite letters. Therefore, , iii F.B of CD, , = 203º 30’ (Fig 3), , i, , B.B of CD, , = F.B of CD - 180º, , = 112º 30’ + 180, , = 203º 30’ – 180, = 23º 30’, iv F.B of DE, , = 320º 30’ (Fig 4), , B.B of DE, , = F.B of DE - 180º, , F.B OF AB, , = N 32º 30’ E (Fig 1), , ∴ B.B of AB, , = S 32º 30’ W, , ii F.B of BC, ∴ B.B of BC, iii F.B of CD, ∴ B.B of CD, , = S 43º 30’ E (Fig 2), = N 43º 30’ W, = S 26º 30’ W (Fig 3), = N 26º 30’ W, , = 320º 30’ - 180º, B.B of DE, , = 140º 30’, , iv F.B of DE, ∴ B.B of DE, , = N 65º 30’ W (Fig 4), = S 65º 30’E, , Construction: Draughtsman Civil - (NSQF Level - 5): Related Theory for Exercise 2.2.46, , Copyright Free under CC BY Licence, , 31

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Exercise, 1 The following are the observed Fore bearing of the, lines:, AB = 88° 30’;, BC = 142° 30’;, CD = 209° 00’;, DE = 324°30’, Find their back bearing., 2 The fore bearings of the lines are as follows:, AB = N26° 30’ E;, BC = S 78° 30’ E;, CD = S 69° 0’ W;, DE = N32° 30 W,, Find their back bearings., , 32, , Construction: Draughtsman Civil - (NSQF Level - 5): Related Theory for Exercise 2.2.46, , Copyright Free under CC BY Licence

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Construction, Related Theory for Exercise 2.2.47 - 2.2.50, Draughtsman Civil - Compass surveying, Determining the bearings of a given triangular plot of ABC and calculation of, included angles, Objectives : At the end of this lesson you shall be able to, • calculate angles from bearings, • calculate bearings from angles, Calculation of Angles from Bearings: When two lines, meet at a point ‘A’ two angles (interior and exterior) are, formed. The sum of these two angles is equal to 360º, (see Fig 1α1 +α 2= 360º), , Both the bearings of the two lines not being measured, from a common station point., Rule: Finding the back bearing of the previous line and, the F.B the next line at that station and use the above, rule for finding included angle., From Fig 2b, the included angle ‘α′ between BC and BA, , ⎣B, , = B.B of AB – F.B of BC, = (180° +θ1) - θ2, , Note: If the difference is less than 180°, then it is an, interior angle and if it exceeds 1800 , it is an exterior angle., The following rules may be adopted to find the included, angle between two lines whose bearings are given., , Case II: Given the bearings in Quadrantal system, i, , Case 1: Given the bearings in whole circle bearing, system, , Referring to Fig 3, in which both the bearings have, been measured to the same side of same meridian., , Both the bearings of the two lines being measured, from a common station point ‘A’., Rule: Subtract the smaller bearing from the greater, bearing. The difference between the two bearings will give, included angle at the station point ‘A’., From Fig 2a, the included angle ‘α′between the lines AC, and AB., LA, , = α = Bearing of AC - Bearing of AB, = θ2 - θ1, , Rule: Included angle, , = difference between the two, bearings AC and AB, , The included angle is α =, , θ2 -θ1, , = F.B of Line AC –, F.B of line AB, ii Referring to Fig 4 both the bearings have been, measured to the adjacent sides of the same meridian., , Rule: Included angle, , = sum of the two bearings AB, and AC, , 33, , Copyright Free under CC BY Licence

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The Included angle ‘α, , = θ1- θ2, = F.B of Line AB +, F.B of line AC, , iii Referring to Fig 5 both the bearings have been, measured to the same side of different meridians., , b 16° 00’ and 332° 30’ (Fig 2), , Rule: Included angle, , = 180° - sum of the bearings, AB and AC, , ⎣ A, Included angle, α = 180° – (θ2 -θ1), iv Referring to Fig 6 both the bearings have been, measured to the opposite side of different meridians., , F.B of OA, , = 16° 00’, , F.B of OB, , = 332° 30’, , ∴ angle ⎣ABOA or α, , = (360° - F.B of line OB), + F.B of line OA, = (360° 00’ - 332° 30’), , Rule: Included angle, , = 180° - difference of the, bearings AB and AC, , + 16° 00, = 27° 30’ + 16° 00’, , L A, Included angle, α = 180° (θ1+ θ2), , = 43° 30’, , Problems on calculation of angles from bearing, C 126° 30’ and 300° 30’ (Fig 3), Example 1, Find the angle between the lines OA and OB, if their, respective bearings are, a 32°30’ and 148° 00’, b 16°00’ and 332° 30’, c 126°30’ and 300°30’, Solution, a 32° 30’ and 148°00’ (Fig 1), F.B of line OA, , = 32° 30’, , F.B of line OB, , = 148° 00’, , ∴ angle LAOB or, , = F.B of line OB –, F.B of line OA, , F.B of OA, , = 126° 30, , F.B of OB, , = 300° 30’, , ∴ angle LAOB or α = F.B of line OB –, F.B of line OA, = 300° 30’ - 126° 30’, , = 148° 00 -32° 30’, , α, 34, , = 115° 30’, , α, , = 174° 00’, , Construction: Draughtsman Civil - (NSQF Level - 5): Related Theory for Exercise 2.2.47 - 50, , Copyright Free under CC BY Licence

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The included angle, α2 or, , Example 2, The following bearings are given in quadrantal systems, of lines AB and AC. Calculate in each case the angle, BAC, Line AB, , Line AC, , i N 25° 30’ E, , S 85° 30’ E, , ii N 20° 30’ E, , N 85° 30’ E, , iii S 70° 00’ E, , S 10° 00’ W, , iv N 50° 30’ E, , S 20° 30’ W, , v N 40° 30’ W, , N 46° 0’ E, , vi S 45° 30’ W, , N 60° 0’ W, , LBAC, , = FB of AC – FB of AB, , α2 =, , =, , (è2 -è1), , = 85° 30’ - 20° 30’, , ⎣ BAC, , = 65° 0’, , iii S 70° 00 E, , S 10° 00 W, , In Fig 3 Refer Case II (ii) both the bearings are, measured to the adjacent sides of the same meridian., , Solution, i, , Line AB, , Line AC, , N 25° 30 E, , S 85° 30’ E, , In Fig 1α1” is the included angle at A or LBAC Ref., Case II (iii) both the bearings have bee measured to, the same side of different meridians., Included angle á3, , = (è1 -è2), = 70° 0’ + 10° 0’, , ⎣ BAC, , = 80° 0’, , v N 50° 30’ E, , S 20° 30’ W, , In Fig 4 From Ref. case II (iv) both the bearings have, been measured to the opposite side of different, meridians., α1, , = 180° - (è1- è2), = 180° - (25° 30’ + 85° 30’), = 180° - 111° 0’, , ⎣ BAC, , = 69° 0’, , ii Line AB, , Line AC, , N 20° 30 E, , N 85° 30’ E, , In Fig 2 Refer case II (i) both the bearings have been, measured to the same side on the same meridian., , á4, , = ⎣ BAC = 180° -(è1 -è2), = 180° - (50° 30’ - 20° 30’), = 180° - 30° 00’, , ⎣ BAC, , = 150° 00’, , v N 40° 30, W, , N 46° 0’E, , In Fig 5 Refer case II (ii), both the bearings have been, measured to the adjacent sides of the same meridian,, included angles, , Construction: Draughtsman Civil - (NSQF Level - 5): Related Theory for Exercise 2.2.47 - 50, , Copyright Free under CC BY Licence, , 35

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= θ5 = θ1 θ2, , ⎣BAC, , = 40 30’ + 46° 00’, , ii 25° 30’ and 340° 30’ (Fig 2), , = 86° - 30’, vi S 45° 30’ W, , N 60° 0’ W, , In Fig 6 Refer case II (iii), both the bearings have been, measured to the same sides of the different meridians., , Included angle á6, , = ⎣BAC = 180° - (θ1 θ2), = 180° - (45° 30 + 60° 0’), = 180° - 105° 30, , ⎣ BAC = α, , = 25° 30’, , Bearing of OB, , = 340° 30’, , The included angles will be difference of the two bearings., ∠AOB, , = 74° 30’, , = Bearing of OB –, Bearing of OA, = 340° 30’ - 25° 30’, , Example 3, , ∠AOB, , Find the angle between the lines OA and OB if their, respective bearings are, i, , Bearing of OA, , = 315º 00’, , Since difference is greater than 180° , it is an exterior, angle, and to obtain the interior angle it, , 25° 30’ and 160° 30’, Must be subtracted from 360°, , ii 25° 30’ and 340 °30’, , ∴Interior angle ∠BOA = 360° -315° 00’, , iii 126° 0’ and 300° 30’, , = 45° 00’, Solution:, ii 126° 0 and 300° 30 (Fig 3), i, , 25° 30’ and 160° 30’ (Fig 1), Bearing of OA, , = 25° 30’, , Bearing of OB, , = 160° 30’, , The included angle will be difference of the two bearings., ∠AOB, , = Bearing of OB –, Bearing of OA, = 160° 30’ - 25° 30’, , ∠AOB, 36, , = 135 °00’, , Construction: Draughtsman Civil - (NSQF Level - 5): Related Theory for Exercise 2.2.47 - 50, , Copyright Free under CC BY Licence

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Bearing of OA, , = 126° 0, , Bearing of OB, , = 300° 30’, , AOB, , = Bearing of OB –, Bearing of OA, , ∠ ABC, , = 245° 30’ - 117° 30’, ∴ Including angle ABC, , = 300 ° 30’ - 126° 0’, ∠ AOB, , = Bearing of BA –, Bearing of BC, , = 128° 00’, , = 174° 30’, , Example 4, Find the angle between the lines AB and BC if their, respective bearings are:, i, , 140° 30’ and 50° 30’, , ii 65° 30’ and 117° 30’, Solution, i, , 140° 30’ and 50° 30’ From Fig 1, , Example 5, The bearing of line AB is 164° 30’ and the angle ABC is, 117° 30’what is the bearing of BC?, Solution, From the Fig 1, , Bearing of AB, , = 140° 30’, , Bearing of BA, , = 180° + 140° 30’, = 320° 30’, , Bearing of BC, , = 50° 30’, , ∠ ABC, , = Bearing of BA –, Bearing of BC, , Find Bearing of BC?, , = 320° 30’- 50° 30’, , Bearing of AB, , =, , 164° 30’, , = 270° 00 the exterior angle, , Bearing of BA, , =, , 180° + 164° 30’, , =, , 344° 30’, , =, , Bearing of BA +∠ ABC, , =, , 344° 30’+117° 30, , =, , 462° 00’ It is more than, 360°, , =, , 462° 00 - 360° 00’, , =, , 102° 00’, , ∴ the interior angle ∠ ABC, = 360° - 270°00’, =, , Now bearing of BC, , 90° 00’, , ii 65° 30’ and 117° 30’ (Fig 2), Bearing of AB, , = 65° 30’, , Bearing of BA, , = 180° + 65° 30’, , ∴ Bearing of BC, , = 245° 30’, Bearing of BC, , = 117° 30’, , Construction: Draughtsman Civil - (NSQF Level - 5): Related Theory for Exercise 2.2.47 - 50, , Copyright Free under CC BY Licence, , 37

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Example 6, , Calculation of bearing from angles:, , The following bearings are observed in a triangular plot, with a compass, calculate in the interior angles., , Referring Fig 1, , Line, , Fore bearing, , AB, , 50° 30’, , BC, , 125° 30’, , CA, , 270° 30’, , Solution, Let α,β,ϒ, δ be the included angles measured clockwise, from back station., , From Fig1, , θ1 be the measured bearing of the line AB., ∴ The bearing of the next line BC, =, , θ2= θ1+ α -180°, , The bearing of the next line CD, =, , θ3=θ2 + β - 180°, , The Bearing of the next line DE, , Included angle at A, ⎣BAC = è1, , =, = BB of CA – FB of AB, , The bearing of the next line EF, , = (270° 30’ - 180°0’) 50° 30’, = 90° 30’ - 50° 30’, ⎣A = è1, , = 40°, , Included angel at B,, ⎣ABC = è2, , = BB of AB –FB of BC, , CBA, , = (50° 30’ + 180° 00) 125° 30’), = 230° 30’ - 125° 30’, , ⎣B, , = 105°00’, , Included angle at C,, ⎣BCA = è3, , = B.B OF BC –, FB OF CA, , ACB, , = (125° 30 + 180° 00) -, , =, , θ5= θ4 + δ -180°, , Note 1, (θ1+α) , (θ2 +β) and (θ3++ ϒ) are more than 180° , while (θ4, +δ) is less than 180° . Hence in order to calculate the, bearing of the next line, the following (Rule in Note 2), statement can be made., Note 2, “Add the measured clockwise angles to the bearing of, the previous line. If the sum is more than 180°, deduct, 180° If the sum is less than 180°, add 180°., In a closed traverse, clock angles will be obtained if we, proceed the traverse in anticlock wise direction., Example 7, , = 305°30’ - 270° 30’, , The following angles were measured in a triangular plot., The bearing of AB is 50° 30’. Find the bearings of BC, and CA if ⎣A= 40° .00, ⎣B= 105°.00, ⎣C= 35°.00., , ⎣C, , = 35° 00’, , Solution (Fig. 1), , Check: ⎣A + ⎣B+ ⎣C, , = 180°, , 40° + 105° +35°, , = 180°, , 270° 30’, , 38, , θ4= θ3++ϒ - 180°, , Construction: Draughtsman Civil - (NSQF Level - 5): Related Theory for Exercise 2.2.47 - 50, , Copyright Free under CC BY Licence

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Bearing of BC, , = BB of AB - ⎣B, = (50° . 30’ + 180) -, , Bearing of CA, , = BB of BC - θC, = (125° . 30 + 180° .0) -, , 105° . 00’, , 35° .00, , = 230° . 30’ - 105° . 00’, , = 305°30’ - 35° 00, , = 125° . 30’, , = 270° 30’, , Determining the bearings of a given pentagonal plot of ABCDE and calculating, included angles, Objectives: At the end of this lesson you shall be able to, • calculate the angles from bearings for a closed traverse, • calculate the bearings from angles for a closed traverse, • calculate the bearings of a pentagon., , Construction: Draughtsman Civil - (NSQF Level - 5): Related Theory for Exercise 2.2.47 - 50, , Copyright Free under CC BY Licence, , 39

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θ2 = ∠B, , Example 1, The following bearings were observed with a compass., Calculate the interior angles. (Fig 1), Line, , Fore Bearings, , AB, , 600 30’, , BC, , 1220 00’, , CD, , 460 00’, , DE, , 2050 30’, , EA, , 3000 00’, , = Bearing of BA - Bearing of, BC, = (1800 + FB of AB) - 1220 0’, = (1800 + 600 30’) - 1220 0’, , θ2 = ∠B, , = 2400 30’ - 1220 0’, = 1180 30’, , Consider station C (Fig 4), , Solution:, Fig 1 shows the plotted traverse by using the above given, fore bearings., Consider station A (Fig 2), , θ 3 = ∠C, , = Bearing of CB Bearing of CD, = (1800 + FB of BC) - 460 0’, = (1800 + 1220 0’) - 460 0’, = 3020 0’ - 460 0’, , θ 3 = ∠C, , = 2560 00’, , In some of the cases in a closed traverse the, calculated included angle exceeds 1800 and, that angle is known as interior angle according, to the traverse as here at station ‘C’., Included angle, θ 1 = ∠A, , = Bearing of previous line Bearing of Next Line, , Consider station C (Fig 5), , = Bearing of AE - Bearing of, AB, = (3000 - 1800) - 600 30’, , θ1, , = 590 30’, , Consider station B (Fig 3), , 40, , Construction: Draughtsman Civil - (NSQF Level - 5): Related Theory for Exercise 2.2.47 - 50, , Copyright Free under CC BY Licence

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θ 4 = ∠D, , = Bearing of DC Bearing of DE, , = (2050 30’ - 1800 ) - 3000, + 3600, , = (1800 + FB of CD) -, , = 250 30’ - 3000 + 3600, θ5 = ∠E, , 2050 30’, , ⎣A, , = 590 30’, , = 2260 00’ - 2050 30’, , ⎣B, , = 1180 30’, , = 200 30’, , ⎣C, , = 2560 00’, , ⎣D, , = 200 30’, , ⎣E, , = 850 30’, , = (1800 + 460) - 2050 30’, θ 4 = ∠D, , ∴, , = 850 30’, , Consider station E (Fig 6), , ---------------sum, , = 5400 00’, ----------------, , The sum of interior angle of a pentagon, = (2n-4) x 900, = (10 - 4) 900 = 5400, Where n, , = No. of sides, , Example 2, θ 5 = ∠E, , = Bearing of previous line, - Bearing of next line, , The bearings of the sides of traverse ABCDE are as, follows. (Fig 1), , = (F.B of DE - 1800 ) - 3000, + 3600, , Construction: Draughtsman Civil - (NSQF Level - 5): Related Theory for Exercise 2.2.47 - 50, , Copyright Free under CC BY Licence, , 41

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Side, , F.B, , B.B, , 0, , AB, , 97 30’, , 2770 30’, , BC, , 120 00’, , 1920 00’, , CD, , 2710 30’, , 910 30’, , DE, , 1890 30’, , 90 30’, , EA, , 1240 30’, , 3040 30’, , Calculate the interior angles of traverse,, Considering the lines ‘AB’ and ‘AE’, Included angle at A, (Fig 2), , ∠C = ∠BCD, , = F.B of CD - B.B of BC, = 2710 30’ - 1920 00’, , ∠C, , = 790 30’, , Considering the lines ‘DE’ and ‘DC’, Included angle at D, (Fig 5), , ∠EAB, , = (3600 - B.B of EA) +, F.B of AB, = (3600 - 3040 30’) + 970 30’, = 550 30’ + 970 30’, , ∠A, , = 1530 00’, , Considering the lines ‘BC’ and ‘BA’, Included angle at B, (Fig 3), , ∠D = ∠CDE, , = F.B of DE - B.B of CD, = 1890 30’ - 910 30’, , ∠D, , = 980 00’, , Consider the lines ‘EA’ and ‘ED’, Included angle at E (Fig 6), , ∠ABC, , = 3600 - BB of AB +, F.B of BC, = (3600 - 2770 30’) + 120 0’, = 820 30’ + 120 0’, , ∠B, , = 940 30’, , Considering the lines ‘CD’ and ‘CB’., Included angle at C, (Fig 4), 42, , Construction: Draughtsman Civil - (NSQF Level - 5): Related Theory for Exercise 2.2.47 - 50, , Copyright Free under CC BY Licence

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∠E = ∠DEA, ∠E, , = F.B of EA - B.B of DE, , Solution, , = 1240 30’ - 90 30’, , For angle at A, (Fig 2), , 0, , = 115 00’, , Check, , ∠A, , = 1530 00’, , ∠B, , = 940 30’, , ∠C, , = 790 30’, , ∠D, , = 980 00’, , ∠E, , = 1150 00’, ---------------, , F.B of AD, , = B.B of DA, , 0, , 540 00’, , For angle at B, (Fig 3), , ---------------Check : The sum of interior angle of a pentagon, = (2n - 4) x 900, = (2 x 5 - 4) 90, = 6 x 90 = 5400 00’, Example 3, The following are the bearings of the lines of a closed, traverse ABCD (Fig 1), F.B of BA, , = B.B of AB, = S 560 30’ W, , F.B of BC, , ∠B, , = S 500 30’ E, = F.B of BC - B.B of AB, = 500 30’ + 560 30’, = 1070 00’, , For angle at C, (Fig 4), , Line, , F.B, , AB, , N 560 30’ E, , BC, , S 500 30’ E, , CD, , S 190 30’ W, , DA, , N 700 30’ W, , Calculate the interior angles of the traverse, , F.B of CB = B.B of BC = N 500 30’ W, F.B of CD, , ∠C, , = S 190 30’ W, = 1800 - (B.B of BC +, F.B of CD), , Construction: Draughtsman Civil - (NSQF Level - 5): Related Theory for Exercise 2.2.47 - 50, , Copyright Free under CC BY Licence, , 43

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= 1800 00’ - (500 30’ + 190 30’), 0, , 0, , = 180 00’ - 70 00’, , ∠C, , = 1100 00’, , For angle at D, (Fig 5), , 3 The following F.B and B.B were observed in traversing, with a compass, Line, , F.B, , B.B, 0, , PQ, , S 37 30’E, , N 370 30’W, , QR, , S 430 15’ W, , N 430 15’E, , RS, , N 740 00’W, , S 740 00’E, , ST, , N 110 00’ E, , S 110 00’W, , TP, , N 570 45’E, , S 570 45’W, , Calculate the interior angles and draw a neat sketch., 4 The bearings of the sides of a traverse ABCDE are as, follows., Side, , F.B, , B.B, , AB, , 1070 15’, , 2870 15’, , BC, , 220 0’, , 2020 0’, , CD, , 2810 30’, , 1010 30’, , = F.B of DA - B.B of CD, , DE, , 1890 15’, , 90 15’, , = 700 30’ + 190 30’, , EA, , 1240 45’, , 3040 45’, , F.B of DC = B.B of CD = N 190 50’E, F.B of DA, , ∠D, ∠D, , 0, , = N 70 30’W, , = 900 00’, , Check :, , ∠A + ∠B + ∠C + ∠D, , = (2n-4) 900, , 530 0’ + 1070 0’ + 1100 + 900 = [(2 x 4)-4 x 900], 3600 00’, = 4 x 900, , Compute the interior angles of the traverse and, exercise the necessary check., 5 The following bearings were taken in running a compass traverse. Find the interior angles and apply the, usual check., AB, , N460 10’E, , BA, , S460 10’W DC, , N90 50’W, , Exercise, , BC, , S600 40’E, , N800 40’W, , 1 The following are the bearings of the lines in a closed, traverse ABCD, , CB, , N600 40’W AD, , 3600, , = 3600, , Fore bearing, , AB, , N 560 20’E, , BC, , S 760 50’E, , Line, , CD, , S 100 40’W, , AB, , N 550 30’E, , DA, , N 800 30’W, , BC, , S 450 30’E, , CD, , S 360 30’W, , DA, , N 520 30’W, , 2 Following are the bearings of lines OA and OB,, calculate the angle AOB in each case., i, , N 30 20’E, , OB, , N 800 20’E, , ii OA, , N 200 20’E, , OB, , S 500 40’E, , OB, 44, , S800 40’E, , F.B, , Apply the necessary check., , 0, , OA, , iii OA, , DA, , S90 50’E, , 6 Determine the values of included angles in the closed, traverse ABCD conducted in clockwise direction, given, the bearings of the sides., , Line, , Calculate the Interior anlges of the traverse, , CD, , Example 4, Find the bearing of the sides of a regular hexagon observed, by going over in a C.W manner if the bearing of one side, is 500., , N 300 30’W, N 350 10’E, Construction: Draughtsman Civil - (NSQF Level - 5): Related Theory for Exercise 2.2.47 - 50, , Copyright Free under CC BY Licence

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Solution, The sum of interior angle of a regular hexagon, , (2n-4) x 900, , =, , =, ∴ The deflection angle i.e. the angle between any side, produced and the side following, (1800 - the interior, angle), 1800 - 1200 = 600, , =, The bearing of AB =, , 500, , It is clear from the Fig 1, that the bearings of each of the, remaining sides taken in a clockwise direction may be, determined by adding 60 to the bearing of the, proceeding side., , Bearing of DE =, , Thus we have,, , Add, , Bearing of AB =, Add, , =, , Bearing of BC =, Add, , =, , Bearing of CD =, Add, , =, , 500, , Bearing of EF, , 600, ------------, , Add, , =, , 600, ------------, , =, , 2900, , =, , 600, ------------, , 1100, Bearing of FA, , 600, ------------, , Add, , 1700, , =, , 3500, , =, , 600, ------------, , 0, , 60, ------------, , 2300, , Bearing of AB = 4100 - 3600 = 500, Which is the bearing of the starting line AB., , Magnetic declination and local attraction, Objectives: At the end of this lesson you shall be able to, • define the dip of the magnetic needle, • state the magnetic declination and variations, • calculate true bearings, • state local attraction and its elimination, • explain about errors and its limits, • state the testing the prismatic compass., Dip of the Magnetic Needle: Before Magnetisation, the, needle remains in the horizontal position if it is properly, balanced, but after being magnetised, it cannot remain in, the same position due to the magnetic influence of the, earth. One end of the needle deflects downward towards, the magnetic pole. In northern hemisphere the north end, of the needle is deflected downward, and in the southern, hemisphere the south end points downward. This, inclination of the needle with the horizontal is known as the, dip of the needle. (Fig 1), , Construction: Draughtsman Civil - (NSQF Level - 5): Related Theory for Exercise 2.2.47 - 50, , Copyright Free under CC BY Licence, , 45

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The amount of the dip is not uniform, but it varies in, different parts of the earth. It varies from 00 to 900 (zero at, equator and 900 at the poles), To keep the needle in the horizontal position,, it is balanced by placing a brass sliding weight, or rider at a suitable point over the higher end, of the needle., Magnetic declination: In certain places, the magnetic, meridian at a place does not coincide with the true, meridian at that place. The horizontal angle which the, magnetic meridian makes with the true meridian is known, as magnetic declination or declination., When the needle is deflected towards east of the true, meridian it is called east declination and west declination, when it is deflected towards west of the true meridian., (Fig.2), , – Secular variation: The magnetic meridian swings, like a pendulum. It swings in one direction for a long, period and gradually comes to rest and then swings, in the opposite direction., – Annual variation: It has a period of one year and, therfore it is known as annual variations. The, amount of variation is in difficult places 0 to ±12, minutes, but it is not remain constant at any place., – Diurnal or daily variation: It is an oscillation of the, needle from its mean position during the day. The, amount of this variation varies from 1 minute to, about 12 minutes at different places., 2 Irregular variations: These are occured by magnetic, storms such as earth quakes or volcanic erruptions, and their amount may be even 10 or 20 at a time. It mat, occured at anytime. It cannot be prediteted., Calculate true bearing problems on magnetic, declination:, Example 1, The magnetic bearing of line is 1970. Find its true bearing,, if the magnetic declination is 30 W, Solution (Fig 1), , The magnetic meridian differs from time to time on the, earth’s surface., Calculation of True bearings:, Rule 1, True bearing of a line = Magnetic bearing of the line ±, declination., , Using Rule 1, True bearing of the line, , =, , Magnetic bearing of the, line ± declination., , Use + sign when the declination is east, , Use - sign because the declination is west., , Use - sign when the declination is west, , True bearing of the line, , =, , Magnetic bearing of the, line - declination., , =, , 1970 - 30, , =, , 1940, , Rule 2, Magnetic bearing of a line = True bearing of the line ±, declination, Example 2, Use + sign when the declination is west, Use - sign when the declination is east, Variations in Declination: The declination is not, constant for any places, but it changes from time to time, and place to place., , If the magnetic bearing of the line is N 370 W and the, magnetic declination is 20 E Find the true bearing., Solution (Fig 2), , The variations may be regular or irregular., 1 Regular variations: This variations may itself be, analysed into several components of different periods, and amplitudes. They are (i) Secular (ii) annual and, (iii) diurnal or daily, 46, , Construction: Draughtsman Civil - (NSQF Level - 5): Related Theory for Exercise 2.2.47 - 50, , Copyright Free under CC BY Licence

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declination is west, ie 20 37’, , From Rule I, True bearing of a line, , = Magnetic bearing of line ±, declination, , Annual variation, , =, , 3’ west, , Variation in 4 years, , =, , 4 x 3’ = 12’ W, , = N(370 - 20) W, , Total declination after 4 years, , 0, , = N 35 W, Example 3, True bearing of a line is 2170 and magnetic declination is, 20 w. Find the magnetic bearing., , =, , 20 37’ + 12’, , =, , 20 49’ W, , True bearing of a line after 4 years, =, , 3240 37’, , (Same as above), , In Fig 3 Magnetic bearing of the line, , magnetic bearing after 4 years, =, , 3240 37’ + 20 49’, , =, , 3270 26’, , Example 5, A line was drawn as its magnetic bearing 2120 on an old, map when the magnetic declination was 40W. To what, bearing should if be set now if the present declination is, 100E., = True bearing of line +, declination., , Solution (Fig 5), , = 2170 + 20, = 2190, Use + sign declination in west., Example 4, The magnetic and true bearing of a line are 3270 14’ and, 3240 37’ respectively. Find the value of the magnetic, declination at the place of observations., If the annual change is 3’ West what would be the, magnetic and True bearing of the line four years since the, date of the above measurement., , When the declination was 40W., True bearing of the line, , Solution, , =, , Magnetic bearing of the, line - declination, , =, , 2120 - 40, , =, , 2080, , When declination is 100 East,, Magnetic bearing of the line =, , 0, , 327 14’, , Magnetic bearing of the line, , 0, , True bearing of the line, , =, , 324 37’, , =, , ∴ Declination, , =, , 3270 14’ 3240 37’, , True bearing of the line, - declination., , =, , 2080 - 100, , 2037’, , =, , 1980, , =, From Fig 4,, , ∴To set the line now to the bearing of 1980, Example 6, Find the magnetic declination if the magnetic bearing of, the sun at noon is, 1 1850, 2 3540, , Construction: Draughtsman Civil - (NSQF Level - 5): Related Theory for Exercise 2.2.47 - 50, , Copyright Free under CC BY Licence, , 47

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Solution (Fig 6), , 4 Find the magnetic declination if magnetic bearings of, the sun at noon, are,, a 1820 00’, b 1780 30’, c 3590 0’, 5 The true bearing of a line is N 300 30’E compute the, magnetic bearing of the line if the magnetic declination, is, a 40 15’E and, b 50 30’W., Local attraction: A magnetic meridian of a place is, established by the magnetic needle which is not attracted, by other attractive forces. Always the magnetic needle, pointing to the magnetic north., , i, , Magnetic Bearing of the line - 1850 (Fig 6 (i), At noon the sun is exactly on the True meridian. Since, the magnetic bearing of the sun is 1850 it is at south, pole, Magnetic declination = 1850 - 1800 = 50 W., , ii Magnetic bearing of the line is 3540 (Fig. 6(ii)), The magnetic bearing of the True north is 3540, Magnetic declination = 3600 - 3540, = 60 to the east of the true, meridian., Magnetic declination = 60 E, Exercise, 1 The magnetic bearing of a line AB is 1250. Find its, true bearing if the magnetic declination at A is, a 90 0’W, , Detection of Local attraction: The local attraction at a, particular place can be detected by observing the fore and, back bearings of each line and finding its difference. If it, differs exactly by 1800 there is no local attraction at both, stations, provided instrumental and observational errors, are eliminated. But if the difference is not equal to 1800, then local attraction exists there either one or both stations., Elimination of Local attraction, If there is local attraction at a station all the bearings, measured at that place will be incorrect. The amount of, error will be equal in all the bearings. There are two, methods for eliminating the effects of local attraction., First method, The amount and direction of error due to local attraction, at each of the affected station is to be calculated., , 0, , b 5 30’E, 2 The true bearing of a line CD is 1380 30’ Find its, magnetic bearing if the magnetic declination at c is, a 50 30’W, b 30 15’E, 3 A line has a true bearing of 2550 . The declination is 30, 30’ E. Calculate the magnetic bearing on whole circle, and reduced bearing systems., , 48, , If the compass is placed under the external attractive, forces, like magnetic rock, iron ore, and also by steel, structures, rails, electric cables, conveying electric, current iron pipes. Iron lamp post etc. may affect the, magnetic needle of the compass. Due to these external, attractive forces, we cannot able to find the normal, position of the magnetic meridian. Such a disturbing force, is known as local attraction., , If the observed bearings are in the whole circle system,, then the correction applied by using the following rule after, finding the nature of error., Rule: If at a station, observed bearing of a line is more, than that of its correct one, the error at this station is +ve, and the correction is -ve and if the error is -ve at this, station, the correction is +ve., If the observed bearings are in the quadrantal system the, corrections must be applied in proper direction., , Construction: Draughtsman Civil - (NSQF Level - 5): Related Theory for Exercise 2.2.47 - 50, , Copyright Free under CC BY Licence

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In I and III quadrants the numerical value of bearings, increased in clockwise direction and II and IV quadrants, they increase in anticlocked wise direction. Hence +ve, corrections are applied for clockwise and -ve corrections, applied for anticlockwise directions., , Error at station E, , 10 00’, , (-), , 304030’, , Observed FB of EA =, Correction at station E, , = (+) 10 00’, -------------, , Example 1, The following bearing was observed in running a closed, transverse, Line, , FB, , Corrected FB of EA =, , 3050 30’, , Deduct, , 1800 00’, , =, , -------------, , BB, =, , 1250 30’, , Observed B.B of EA =, , 1250 00’, , Correct B.B of EA, 0, , 0, , 75 00’, , AB, , 254 30’, , BC, , 0, , 0, , 115 30’, , 296 30’, , CD, , 0, , 165 30’, , 3450 30’, , DE, , 2250 00’, , 440 00’, , EA, , 3040 30’, , 1250 00’, , ------------(-) 00 30’, , Error at station A, , ------------Observed F.B of AB =, , 750 00’, , Find the error due to local attraction. Determine the, correct bearings., , Correction at station A, , (+)00 30’, , Solution, , Corrected FB of AB, , =, , 750 30’, , Add, , =, , 1800 00’, , Line, , FB, , BB, , Error, , AB, , 750 00’, , 2540 30’, , 00 30’, , BC, , 1150 30’, , 2960 30’, , 10 00’, , CD, , 1650 30’, , 3450 30’, , NIL, , DE, , 2250 00’, , 440 00’, , 10 00’, , EA, , 3040 30’, , 1250 00’, , 00 30’, , -------------, , ------------Corrected BB of AB =, , 2550 30’, , Observed BB of AB =, , 2540 30’, ------------(-) 10 00’, , Error at station ‘B’, , ------------From the above calculation we came to know that the, stations C and D are free from local attraction and all other, stations are having local attractions. Hence the observed, bearings at the stations C and D are correct., , Observed F.B of BC =, Correction at station ‘B’, , = (+) 10 00’, , Commencing from the fore bearing of ‘DE’ all other, incorrect bearings can be calculated as follows., Observed F.B of DE =, , 2250 00’, , Deduct, , 1800 00’, , =, , ------------Corrected FB of BC =, , 1160 30’, , Add, , 1800 00’, , =, , -------------, , ------------Corrected B.B of DE =, , 450 00’, , Observed B.B of DE =, , 440 00’, , 1150 30’, , Corrected B.B of BC =, , 2960 30’, -------------, , Observed B.B of BC’ =, , -------------, , 296.30, , Corrected, Line, , F.B, , B.B, , Correction, , FB, , BB, , AB, , 750 00’, , 2540 30’, , (+) 00 30’ at ‘A’, , 750 30’, , 2550 30’, , BC, , 1150 30’, , 2960 30’, , (+) 10 00’ at ‘B’, , 1160 30’, , 2960 30’, , CD, , 1650 30’, , 3450 30’, , Nil at ‘C’, , 1650 30’, , 3450 30’, , DE, , 2250 00’, , 440 00’, , Nil at ‘D’, , 2250 00’, , 450 00’, , EA, , 3040 30’, , 1250 00’, , (+) 10 00’ at ‘E’, , 3050 30’, , 1250 30’, , Construction: Draughtsman Civil - (NSQF Level - 5): Related Theory for Exercise 2.2.47 - 50, , Copyright Free under CC BY Licence, , 49

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Observed B.B of BC = N 610 30’ W, , Example 2, The following bearings were taken in traversing with a, compass in a place where local attraction was suspected., Line, , F.B, , B.B, , AB, , N 460 00’E, , S 460 00’W, , BC, , S 600 30’E, , N 610 30’W, , CD, , S 100 30’E, , N 90 00’W, , DA, , N 790 00’W, , S 790 30’E, , Difference, , = (+) 10 00’ error at ‘c’, , Observed F.B of CD, , = S 100 30’E, , Correction at C’, , = (-) 10 00’, ------------------, , Corrected FB of CD, , = S 90 30’E, , Corrected B.B of CD = N 90 30’W, Observed B.B of CD = N 90 00’ W, ------------------, , At what station do you suspect local attraction?, Determine the correct bearings of each line., , (-) 00 30’ error at D, , Difference, , -----------------Solution, If the numerical value of Fore and Back bearings of a line, is same there is no local attraction. Examining the above, problem the station A and B are free from local attraction., The stations C and D are having local attraction and to be, corrected., , Observed F.B of DA, , = N 790 00’W, , Correction at D, , = (+) 00 30’, ------------------, , Corrected F.B of DA, , Corrected B.B of DA = S 790 30’E, ------------------, , Fore and Back bearings of AB are correct., Observed BB of DA, , = S 600 30’E, , Fore bearing of BC, , = N 790 30’W, , = S790 30’ E, ------------------, , Corrected B.B of BC = N 600 30’ W, Hence error at A is NIL., Corrected, , Remarks, , Observed, , Line, , F.B, , B.B, , FB, , BB, , Correction, , AB, , N 460 00’E, , S 460 00’W, , NIL at ‘A’, , N 460 00’ E, , S 460 00’ W, , BC, , S 600 30’E, , N 610 30’W, , NIL at ‘B’, , S 600 30’ E, , N 600 30’ W, , CD, , S 100 30’E, , N 90 00’W, , -10 00’ at C, , S 90 30’ E, , N 90 30’ W, , DA, , N 790 00’W, , S 790 30’E, , + 00 30’ at D, , N 790 30’ W, , S 790 30’ E, , attraction. Consequently bearings taken at these stations, are correct.Fore and back bearings of CD are correct., , Example 3, The following bearings were recorded for a closed, compass transverse, Line, , F.B, , B.B, , AB, , 740 30’, , 2560 00’, , BC, , 1070 00’, , 2860 30’, , CD, , 2240 30’, , 440 30’, , DA, , 3080 00’, , 1270 00’, , F.B of DA, , = 3080 00’, , Subtract, , = 1800 00’, ------------, , Corrected B.B of DA = 1280 00’, Observed B.B of DA = 1270 00’, ------------Difference, , Which stations are affected by local attraction. Determine, the correct bearings. Find the true bearings if the, declination was 20 00’ west, Solution, , (-) 10 00’ error at A, --------------, , Observed F.B of AB, , = 740 30’, , Correction, , = (+) 10 00’, -------------, , Fore and Back bearings of the line CD differ exactly by, 1800, therefore stations C and D are free from local, 50, , Construction: Draughtsman Civil - (NSQF Level - 5): Related Theory for Exercise 2.2.47 - 50, , Copyright Free under CC BY Licence

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Corrected F.B of AB, , = 750 30’, , Corrected F.B of BC, , = 1060 30’, , Add, , = 1800 00’, , Add, , = 1800 00’, , -------------, , -------------, , 0, , Corrected B.B of AB, , = 255 30’, , Corrected B.B of BC = 2860 30’, , Observed B.B of AB, , = 2560 00’, , Observed B.B of BC = 2860 30’, , ---------------, , Hence O.K, , 0, , (+) 0 30’ error at ‘B’, , Which agrees to the given B.B of BC observed at the, station C which is free from local attraction. Having, corrected the bearings of the lines, their true bearings, may be determined by subtracting 20 00’ from the corrected bearings of the lines, since the magnetic declination is west. The results may be tabulated as follows., , Observe F.B of BC, , = 1070 00’, , Correction at B, , = (-)00 30’, -------------, , Line, , Observer, F.B, , Correction, , Corrected, , B.B, , F.B, , Decli, nation, , B.B, , AB, , 740 30’, , 2560 00’ (+) 10 at A, , 750 30’, , 2550 30’, , BC, , 1070 00’, , 2860 30’ (-) 00 30’ at B, , 1060 30’, , 2860 30’, , CD, , 2240 30’, , 440 30’, , 00 at C, , 2240 30’, , 440 30’, , DA, , 3080 00’, , 1270 00’ 00 at D, , 3080 00’, , 1280 00’, , True, F.B, , Remarks, B.B, , 730 30’, , 2530 30’, , 1040 30’, , 2840 30’, , 2220 30’, , 420 30’, , 3060 00’, , 1260 00’, , Stations C and D are free, from local attraction, , ---------------, , Declination being 20 00’ W, T.B of a line = MB - 20, , Difference, , Solution, , Second method, In this method the included angles for all stations are, computed from the observed bearings and check it with, the sum of theoritical angles and correct the angles. Then, commencing from the unaffected line and using these, included angles the correct bearings of the successive, lines are computed., Example 4, The observed bearings of the lines AB, BC, CD and DA, are as follows, Find which station is free from local, attraction and workout the correct bearings., , On examining the values of the observed bearings of the, lines, it will be seen that Fore and Back bearings of the line, AB only differ by 1800. Stations A and B are therefore both, free from local attraction and the observed Fore and Back, bearings of AB are correct. Now the true included angles, between the lines are computed from the observed, bearings of the lines., From the Fig 1, , ∠A = 990 30’ - 460 00, , = 530 30’, , ∠B = 2260 00’ - 1190 30’, , = 1060 30’, , ∠C = 2990 00’ - 1700 00’, , = 1290 00’, , ∠D = 3510 00 - 2800 00, , = 710 00’, , Line, , F.B, , B.B, , AB, , 460 00’, , 2260 00’, , BC, , 1190 30’, , 2990 00’, , CD, , 1700 00’3510 00’, , ∠A = 530 30’, , Theoretical Check, , DA, , 2800 00’990 30’, , ∠B = 1060 30’, , (2n - 4) 900, , ∠ C = 1290 00’, , (2x 4 – 4) 900, , Construction: Draughtsman Civil - (NSQF Level - 5): Related Theory for Exercise 2.2.47 - 50, , Copyright Free under CC BY Licence, , 51

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∠ D = 710 00’, , 4 x900 = 3600, , The following bearings were observed on a compass, traverse., , Total 3600 00’, Fore bearings of AB, , =, , 460 00’, , Add, , =, , 180000’, , B.B of AB, , =, , 2260 00, , Subtract ∠B, , =, , 1060 30’, , =, , 1190 30’, , =, , 1800 00’, , =, , 2990 30’, , =, , 1290 00’, , Fore bearing of BC, Add, Corrected B.B of BC, Subtract ∠ C, , Exercise 1, , Line, , F.B, , B.B, , 0, , 2600 00’, , AB, , 80 30’, , BC, , 130030’ 311030’, , CD, , 2400 30 600 30’, , DA, , 290030’ 11000’, , Make correction for local attraction and declination of 1030’, W and calculate true bearings., Exercise 2, , Corrected fore bearing, of CD, , =, , 1700 30’, , Add, , =, , 180000’, , Corrected B.B of CD, , =, , 3500 00’, , Subtract∠D, , =, , 710 00’, , The following are the bearings taken on a closed compass, traverse., Line, , F.B, , B.B, , AB, , S 370 30’E, , N 370 30’ W, , Corrected fore Bearing of DA, =, , 2790 30’, , BC, , S 430 15’W, , ’N 440 15’ E, , Subtract, , =, , 1800 00’, , CD, , N 730 00’W, , S 720 15’ E, , Fore bearing of AB, , =, , 460 00’, , DE, , N120 45’ E, , S130 15’ W, , EA, , N600 00’ E, , S590 00’’ W, , Which agrees to the given FB of AB observed at station, A, which is free from local attraction., , Compute the interior angles and correct them for, observational errors., Permissible Error in compass surveying: The, Permissible Error should not exceed 7½minute. But due, to magnetic changes and variations of declination the, error should not exceed 10 minutes., , 52, , Construction: Draughtsman Civil - (NSQF Level - 5): Related Theory for Exercise 2.2.47 - 50, , Copyright Free under CC BY Licence

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Plotting of a compass traverse, Before plotting traverse on the drawing sheet, first to draw, a rough sketch on the paper., From this we can able to know the size and shape of the, plan and also the best way to arrange it on the drawing, sheet., From the observed bearings, corrected bearings are, calculated before plotting., The following methods are used for plotting a traverse, survey., By parallel meridian through each station (Fig 1), From the corrected bearings, the included angles are, calculated., From the starting station A, draw a line representing the, magnetic meridian., From A, draw the bearing of the line AB, and cut off the, length AB according to scale, thus fixing of the station ‘B’, From B draw the included angle ABC., The same process may be repeated at each successive, stations., By paper protractor (Fig.3), First fix the position of the starting point P on the paper., From this point P draw the magnetic meridian., Plot the bearing of the line PQ with the protractor., Cut the length of the line PQ with suitable scale., Now the station point Q is fixed., From Q, draw a line which is parallel P to magnetic, meridian., Plot the bearing of the line QR and cut off the length of, line QR., Repeat the same process until all the lines are drawn., If the traverse is a closed one the last line must coincise, with the starting station P., If not the error is called as closing error., , First mark any point ‘O’ on the paper and draw the bearing, of each line with reference to the magnetic meridian by, using large circular paper protector is shown in Fig a., Transfer the direction of all the lines to their proper, positions and taking length of each lines is shown in, Fig b., By rectangular co-ordinate method (Fig 4), , By included angle method (Fig 2), , Firstly, the points of traverse are plotted by their, coordinates with respect to x-axis and y-axis. The x axis, and y axis are intersecting at ‘O’, , Before plotting the included angle method of the corrected, bearings are calculated first, from the observed bearings., , •, , The line OX is representing the magnetic meridian., , • Every point is plotted independently with reference to, the axes., Construction: Draughtsman Civil - (NSQF Level - 5): Related Theory for Exercise 2.2.47 - 50, , Copyright Free under CC BY Licence, , 53

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Adjustment, 1 Draw a straight line AA’ equal to the perimeter of the, traverse to a suitable scale., Firstly, the co-ordinates of each point are calculated., This method is mainly used in plotting of traverse by using, Theodolite instrument., • It is more accurate method of plotting., • In this method the errors are not accumulate., , 2 Draw A’A” parallel and equal to the closing error AA’, and join AA”., 3 Draw a parallel line through B, C, D and E to meet the, B’, C’, D’ and E’, 4 Draw parallel lines through the plotted station B, C, D, and E and plot the errors equal to BB’, CC’, DD’ and, EE’ in direction parallel to A’A”., 5 Join the points AB’C, D’E A to get the adjusted traverse., , Closing Error and its graphical Adjustments: While, plotting a closed traverse the starting and the ending, points will coincide otherwise if the ending points fails to, meet with the starting one is called the closing error or, error of closure., , Sources of Error in Compass Survey:, The errors in compass instrument may be:, 1 Instrumental errors., , The closing error occurs due to wrong, measurement of lengths and bearing of lines, in the field are due to faulty plotting., , 2 Errors due to manipulation and sighting., , When the closing error exceeds permissible, limit, the field work is repeated. But the error, is found to be within the permissible value, the, traverse may be adjusted., , I, , When the angular and linear measurements are of equal, precision graphical adjustment of the traverse may be, used. This method is based on the Bowditch’s rule., The correction may be applied both lengths as, well as to bearings of the lines in proportion to, their lengths., , The adjustment of a compass traverse graphically, may, be made as under., , 3 Errors due to external influence., Instrumental Error:, , 1 The needle not being straight., 2 The pivot being bent., 3 The needle having lost is magnetism., 4 The pivot point being blunt., 5 The needle neither moving quite horizontally nor, moving freely on the pivot due to the dip of the needle., 6 The plane of sight not being vertical., 7 The vertical hair being to thick or loose., 8 The line of sight not passing through the centre of the, graduated circle., II Errors due to manipulation and slighting, , Procedure (Fig 5), Let ABCDEA be a closed traverse as plotted from the, observed magnetic bearings and linear measurements, of the traverse lengths. A is the starting station and A is, the location of the station a as plotted. Hence, A’ A is the, closing error., , 1 Inaccurate centering of the compass, 2 Carelessness in reading, 3 Carelessness in recording, 4 Improper bisecting and ranging., 5 Inaccurate levelling., , 54, , Construction: Draughtsman Civil - (NSQF Level - 5): Related Theory for Exercise 2.2.47 - 50, , Copyright Free under CC BY Licence

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III Errors due to external influences., 1 Variations in declination, 2 Local attraction, 3 Magnetic changes., 4 Irregular variations due to magnetic storms, earthquakes etc., Testing and adjustments of the compass, The compass should be tested and adjusted as explained, below., 1 When the compass is levelled the needle or ring, should be horizontal if not, slide the rider on the higher, end of the needle to make it horizontal., , To ascertain if the needle is sluggish, take a reading, in any position of the needle being in rest. Then, displace the needle by bringing near it a piece of steel, or bunch of keys etc. and let it come to rest and then, again take the reading., The reading will be the same if there is no friction on, the pivot and the needle is not sluggish. If reading is, not the same, then the pivot point should be sharpened, by a fine oil stone and the needle should be, remagnetised by a bar magnet., 3 To see if the sights are fixed diametrically opposite to, each other, stretch a fine horse-hair between the, sights. It will pass over the N and S marks., 4 To detect if there be any error due to careless working, on external influence, take the fore and back bearing, of a line and this differ exactly by 180º if the work is, correct and there is no external influence., , 2 The needle should be sensitive so that it may not come, to rest in a direction other than the magnetic meridian., , Construction: Draughtsman Civil - (NSQF Level - 5): Related Theory for Exercise 2.2.47 - 50, , Copyright Free under CC BY Licence, , 55

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Construction, Related Theory for Exercise 2.3.51 - 2.3.52, Draughtsman Civil - Plane table surveying, Instrument used in Plane table surveying, Objectives : At the end of this lesson you shall be able to, • state plane tabling, • name the Instruments and Accessoriees used in plan tabling, • state the construction and and uses of Instruments and Accessories of plane tabling, • explain about Levelling, centering and orientation in plane tabling, • explain the methods of plane tabling., Plane tabling: Plane tabling is graphical method of, surveying in which field observations and plotting are done, simultaneously on a plane table., It is most suitable for filling in the various details between, the stations previously fixed by triangulation., It is commonly used for preparing small scale mapping, or medium size mapping. This type of survey is employed, when great accuracy is not required such as, Topographical surveys., , Instruments used in plane tabling, -, , Plane table with Tripod, , -, , Alidade, , Accessories used in plane tabling, -, , Spirit level, , -, , Trough compass, , -, , Plumbing fork with plumb-bob & water proofing cover., , Plane Table with Tripod etc: Plane table is made of, well-seasoned good quality teak or pine wood and is, available in different sizes., -, , Small: 50cm x 40cm x 1.5cm, , -, , Medium: 50cm x 50cm x 1.5cm, , -, , Large: 75cm x 60cm x 1.5cm, , It is mounted on a Tripod in such a way that it can be, levelled, rotated about a vertical axis and clamped in any, position. The upper surface of the board must be perfectly, plane. The tripod is generally of the open frame type and, can be folded (Fig 1) for convenience of transportation., Qualities of a Good Plane Table:, -, , The butterfly nuts which clamp the legs to the clamping, head should not be free., , -, , The clamping assembly should fit the plate at the, bottom of the plane table., , The Alidade:The Alidade is a straight edge with some, form of sighting device. Two types of alidades are, generally used., , – Plain Alidade, – Telescopic alidade, Plain Alidade:Itconsists of a metal or wooden rule with, two vanes at the ends. Vanes are hinged and can be, folded on the rule when the alidade is not in use (Fig 2), One of the vanes known as sight vane is provided with a, narrow slit with three holes, one at the top, one at the, bottom and one in the middle., The other vane which is known as object vane is open, and carries a hair stretched between the top and bottom, of the slit. With the help of the slit, a definite line of sight, may be established parallel to the ruling edge of the, alidade. The alidade can be rotated about the point which, , 56, , Copyright Free under CC BY Licence

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represents the location of the instrument station on the, sheet so that the line of sight passes through the station, sighted. The two vanes should be perpendicular to the, ruler as well as surface of the plane table. The working, edge of the alidade is called fiducial edge., The plain alidade can be used when the elevations or, depressions of the objects are low., , Telescopic Alidade: It is generally used when it is, required to take inclined sights. The telescope increases, the range and accuracy of the sights. It consists of a, small telescope with a level tube. A graduated scale is, mounted on a horizontal axis. The horizontal axis rest, on a A-frame which is supported on a heavy metal ruler., One side of the ruler is used as working edge. (Fiducial, edge) along which lines may be drawn. The angles both, elevation and depression can be read on the vertical circle, (Fig 3)., Sprit Level:A spirit level consists of a small metal tube, which contains a small bubble at centre. The Base of, spirit level must be flat so that it can be laid on the table., When table remains central, the table is truly level (Fig 4), , Trough compass or magnetic compass: A box, compass consists of a magnetic needle pivoted at its, centre freely. It is used for making the direction of the, magnetic meridian on the sheet. So it is also used for, orienting the plane table to magnetic north. Both the, edges of a compass are straight, and bottom surface is, flat. The magnetic needle should be fairly sensitive and, play freely (Fig 5), Plumbing fork with bob: The fork consists of a hair pin, shaped light metal frame having two arms of equal length,, in which a plum-bob is suspended from the end of the, lower arm (Fig. 6), Construction: Draughtsman Civil - (NSQF Level - 5): Related Theory for Exercise 2.3.51 - 52, , Copyright Free under CC BY Licence, , 57

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The fitting can be places with the upper arm lying on the, top of the table and the lower arm below it, the table being, centered when the plumb-bob hangs freely over the, ground mark and the pointed end of the upper arm, coincides with the equivalent point on the plan., It is used for centering the table over the point or station, occupied by the plane table when the plotted position of, that point is already known on the sheet. In the begining, of the work it is meant for transferring the ground point, on to the sheet so that the plotted point and the ground, station are in the same vertical line., Setting up the plane Table, The setting up the plane table involves three operations., 1 Levelling the plane Table, 2 Centering the plane Table, 3 Orienting the plane Table., Levelling the plane Table: In this operration, the table, top is made truly horizontal. For rough and small scale, works, levelling of table can be done by eye estimation,, and for large scale works levelling of table can be done, by using spirit level. The levelling is specially important, in hilly terrain where some of the control points are, situated at the higher level and some other at lower level, (Fig 7)., , Orienting the plane table: It is the process of putting, the plane table in to some fixed direction so that the line, representing a particular direction on the plan is parallel, to the direction on the ground. Orientation is necessary, when more than one instrument station is to be used. If, orientation is not done, the table will not be parallel to, itself at different positions resulting in an overall distortion, of the map. The process of centering and orientation, are dependent on each other. For orientation, the table, will have to be rotated about its vertical axis, thus, disturbing the centering., Orientation by back sighting (Fig 9), , The table is set up on the station B and it is represented, as ‘b’ on the paper which is plotted by means of a line ab, from the back station A. Now, the orientation is bringing, ba on the paper over. BA on the ground. Placing of alided, on ba, turn the table till the station ‘A’ is bisected. The, clamp the load in this position., Orientation by magnetic needle, , Centering the plane Table: In this operation, the, location of the plane table station, on the paper is brought, exactly vertically above the ground station position. For, rough works exact centering of the station is not, necessary but for large scale maps and accurate works, exact centering is required . (Fig 8), , 58, , For orientated the table at any station other than the first, station, but the trough compass on the meridian already, drawn on the paper at the first station and turn the table, till the ends of the needle are opposite the zeros of the, scale towards north – south direction. At this position, clamp the board. This is the quick method but unsuitable, for magnetic area., , Construction: Draughtsman Civil - (NSQF Level - 5): Related Theory for Exercise 2.3.51 - 52, , Copyright Free under CC BY Licence

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Method of plane table survey, Objectives : At the end of this lesson you shall be able to, • methods of plane table survey, • radiation method of plane table survey, • intersection method of plane table survey., The following arethe four methods of plane table survey., •, , Radiation, , •, , Intersection, , •, , Traversing, , •, , Resection, , Note: This method is suitable for the survey, of small areas which can be commanded from, single station., ·It is also useful in combination with other methods for, surveying details within a tape length from the station., Intersection Method:, , Radiation Method, The Plane table is set up at only one station and various, points are located by radiating lines drawn from the, instrument station to each of the points and plotting to, scale along the ray drawn with the distance measured, from the station to the point sighted., (Fig 1), , •, , In this method of the positions of the points are fixed, on the sheet by the intersection of the rays drawn, from two instrument stations., , •, , The line joining these two stations are termed as base, line., , •, , This is the only linear measurement taken in the field., , •, , It is largely employed for locating details and for, locating the points to be used subsequently as, instrument stations., , •, , It is also used for plotting the distant and inaccessible, objects, broken boundaries, river etc., , •, , It is more suitable for surveying hilly country where it, is not possible to measure the horizontal distances,, difficult to measure the horizontal distances., , Procedure (Fig 2), , •, , Select a point P such that all the points to be located, are visible from the point., , •, , Set up and level the table at P and clamp it., , •, , Select a point ‘p’ on the sheet and make it vertically, above ‘P’ on the ground by the use of ‘U’ frame., , •, , The point ‘p’ represents on the sheet as the station, ‘P’ on the ground., , •, , Mark the direction of the magnetic meridian with the, trough compass in the top corner of the sheet., , •, , With the alidade touching ‘p’ sight the various points, A, B, C, D and E etc to be located and draw radial, lines towards them along the fiducial edge of the, alidade., , •, , Measure the radial distance PA, PB, PC, PD and PE, with the tape., , •, , Plot the distance to scale along the corresponding, rays. Join the points a, b, c, d, e on the sheet., , •, , Select two points A and B on the ground, so that all, points to be plotted are visible from both the station., , •, , Set up and level the plane table at station A and mark, a suitable point ‘a’ on the paper, so that it is vertically, above the instrument station A on the ground., , •, , Mark the direction of magnetic meridian on the top, corner of the sheet by means of a trough compass., , Construction: Draughtsman Civil - (NSQF LEvel -5): Related Theory for Exercise 2.3.51 - 52, , Copyright Free under CC BY Licence, , 59

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•, , With the alidade touches on the point ‘a’ sight the, station B and other points 1,2,3 etc to be located and, draw rays towards them., , •, , Orient the table by placing the alidade along ‘ba’, turning the table till the line of sight stricks ‘A’ and, clamp it., , •, , Make the respective lines by letter b, 1,2,3 etc to avoid, confusion., , •, , With the alidade pivoted on ‘b’ draw rays sighting, towards the same objects (ie) 1,2,3,4 etc., , •, , Measure the base line AB with a steel tape or chain, cut off distance ‘ab’ to scale along the ray from ‘a’ B., , •, , •, , This is the position ‘b’on the sheet of the station ‘B’, on the ground., , The intersections of these rays with the respective, rays from “a” determine the positions of the object, 1,2,3,4 on the sheets., , •, , Shift the instrument and set it up and level at ‘B’ such, that the point ‘b’ is exactly above the point B on, theground., , Traversing method of plane table survey, Objectives : At the end of this lesson you shall be able to, • state traverse method of plane table survey, • conduct traverse method of plane table survey., Traversing, •, , This is main method of plane tabling and similar to, that of compass or Theodolite traversing., , •, , It is used for running survey lines of a closed traverse, or open traverse., , •, , The details may be located by offsets taken in the, usual manner (i.e.) by the radiation or by inter section, method of plane tabling., , Procedure, , •, , Measure the distance AB and Scale off ‘ab’. Thus, fixing of the position of ‘b’ on the sheet which, represents the station ‘B’ on the ground., , •, , Locate the near by details by offsets taken in the usual, manner or by radiation and distant objects by, intersection method., , •, , Shift the table and set it up at ‘B’ with ’b’ over ‘B’ and, orient it by placing the alidade along ba, turning the, table till the line of sight strikes ‘A’ and then clamp it., , •, , With the alidade touching ‘b’ sight ‘C’ draw a ray., , •, , Measure the line BC and cut off ‘bc’ to scale., , •, , Select the traverse station A, B, C, D etc. on the, ground., , •, , Locate the surrounding details are taken before in, station ‘B’., , •, , Set up the table over one of them say ‘A’ select a, point ‘a’ suitably on the sheet. Level and centre the, table over ‘A’., , •, , Proceed similar to the other stations, in each case, orienting by a back sight before taking the forward, sight until all the remaining stations are plotted., , •, , Mark the direction of the magnetic meridian on the, top corner to the sheet by means of the trough, compass., , •, , With the alidade touching ‘a’ sight ‘B’ and draw a ray., , 60, , Check, •, , Intermediate checks should be taken wherever, possible. If ‘A’ is visible from C, the work done, up to, ‘C’ can be checked by sighting ‘A’ with the alidade, touching ‘C’ and noting if the edge touches ‘a’ similarly, other check lines DB, EC etc can be used to the check, the work., , •, , When no other stations are visible from the station, occupied, take some well-defined object such as, corner of a building which has been previously fixed, on the sheet and it should be used to check the work., , Construction: Draughtsman Civil - (NSQF): Related Theory for Exercise 2.3.51 - 52, , Copyright Free under CC BY Licence

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Resection method of plane table survey, Objective : At the end of this lesson you shall be able to, • state the resection method of plane table survey, , Resection Method, , •, , With the alidade touching ‘b’ sight the station ‘C’ which, is to be plotted by resection and draw a ray., , •, , Estimate the distance BC by judgement only and, move the point ’C’ and along a ray to represent the, approximate position of ‘C’, , •, , It is used for locating the station points only., , •, , The main feature of resection is that the point plotted, on the sheet is the station occupied by the plane table., , •, , After stations are fixed the details are taken by, radiation or intersection, or sometimes both., , •, , Shift the table and set it up with C, on the ground, point ‘C’., , •, , Select a base line AB on the ground., , •, , •, , Measure the distance accurately and then plot ‘ab’, in a convenient position., , Orient the table by taking back sight on ‘B’ and clamp, it., , •, , With the alidade pivoted on ‘a’ sight the station ‘A’, and draw a ray., , •, , The point of intersection of this ray and that previously, drawn from ‘b’ gives the required point ‘C’ (i.e.) true, position of ‘C’., , •, , It necessary locate the other station in the above, manner. It is also know as back ray method., , •, , Set up and level the table at ‘B’ so that ‘b’ lies vertically, above B and orient the table by placing the alidade, along ‘ab’ and turning the table till ‘A’ is bisected and, then clamp it., , Construction: Draughtsman Civil - (NSQF Level 5): Related Theory for Exercise 2.3.51 - 52, , Copyright Free under CC BY Licence, , 61

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Locate and plot new building by two point and three point problem, Objectives : At the end of this lesson you shall be able to, • define about resection, • state two and three point problem, • describe Lehman’s rule, • list out the errors in plane tabling, • describe the advantages and disadvantages., Resection Method, The process of determining the location of the station, points occupied by the plane table, by means of drawing, back rays from the stations whose locations have already, been plotted on the sheet is called resection., , Fig 2 shows A, B and C are three well defined objects a,, b and c their plotted positions on the plan. P is the, instrument station and ‘p’ is its required position the plan., , This method consists of drawing rays from known points, whose locations are already available on the sheet. The, intersection of these rays will be at a point if the orientation, of the table was correct before rays are drawn. The, problem, therefore, lies in orienting the table at the, unknown occupies station., It may be solved by any one of the following methods., , The three points problem may be solved, 1 By mechanical method (Tracing paper method), , 1 Two-point problem, , 2 By graphical method (Bessel’s method), , 2 Three point problem, , 3 By trial and Error method, Two-point problem: The two-point problem consist in, establishing the position of the instrument station on the, plan by making sights towards two well defined objects, which are visible from the instrument station and whose, positions have already been plotted on the plan., In Fig 1, A and B are the well-defined objects, ‘a’ and ‘b’, their plotted positions on the plan., , Mechanical or Tracing Paper Method: In this method, a tracing paper is used over the drawing sheet in which, the plotted positions of (a, b and C) the known objects, (A, B and C) are drawn. The back rays are drawn on the, tracing paper by sighting the known objects. The, intersection of the above three rays will give instrument, position on the tracing sheet. By unfastening and, adjusting the tracing paper over the plotted positions of, the object on the drawing sheet will give the new, instrument position of the station occupied by the plane, table., Graphical or Bessel’s method: In this method any two, of three known object points and its plotted positions on, the drawing sheet are taken for solving the problem., Mechanical Method, It is also called as tracing paper method., , ‘C’ is the instrument station and ‘c’ is its required position, on the plan. ‘P’ is the helping station to find out the, instrument station which is to be occupied by the plane, table. ‘R’ is the position of Ranging rod., Three-point problem:Three point problem consists in, establishing the position of the instrument station on the, plan by making sights towards three well defined objects, which are visible from the instrument station and whose, positions have already been plotted on the plan., 62, , •, , Set up the plane table at ‘T’, , •, , Orient the table as nearly in its proper position using, by trough compass and clamp the board., , •, , Put the tracing paper over the plane table sheet and, select a point ‘t’, on the tracing paper approximately, representing the station point ‘T’ (Fig 3), , •, , With the help of alidade touching on t1 (pivoted on, t1) sight the station points A, B and C and draw rays, towards them., , Construction: Draughtsman Civil - (NSQF Level - 5): Related Theory for Exercise 2.3.51 - 52, , Copyright Free under CC BY Licence

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•, , Unfasten the tracing paper and move it over on the, plane table sheet, till the three rays are simultaneously, pass through a, b and c. Prick the point t1 on the, drawing sheet with fine needle point. The obtained, point it is the required point ‘T’ (Fig 3), , •, , Remove the tracing paper., , •, , Unclamp the plane table and orient by placing the, alidade ta and turning the board till the station ‘A’ is, bisected., , •, , For a check, sight the station points B and C with the, help of alidade centered on b and c, and draw the, rays., , These rays must pass through T if the work is correct. If, not, a small triangle error is formed and this may be, eliminated by trial and error method., Bessel’s Method, It is the simplest graphical method and is commonly used., Set up and level the plane table at the instrument station, at ‘T’., Turn the table till the station ‘P’ is sighted. i.e. (P is towards, P), Clamp the plane table., The alidade is touching r and sight φ and draw a ray rφ, (Fig.4 A), Fig 4. B, Unclamp the plane table. Put the alidade along rp and, turn the plane table till R Station R is bisected. i.e(r is, towards R), The clamp the plane table. The alidade touching on P, and sight Q and draw a ray PQ intersecting the previous, ray rQ in the point at d., Fig. ( 4 C), Put the alidade along dq, turn the plane table till Q is, sighted and clamp the table. This is the correction, orientation e.e (P must lie on dq and also PQ and Rr., Put the alidade on P Sight P and draw a ray. This ray will, intersecting the ray dq in p which is the instrument station, P., , As for the checking purpose, centre the alidade on r and, bisect ‘R’ and draw ray. This ray Rr should pass through, P if the work is correct., By trial and error method: From the above three, methods trial and error method is quick and accurate, method. It is also known as triangle of error method., The position of the instrument station occupied by the, plane table on the drawing sheet is found by Trial and, Error method., In this method the plane table is set up infront of the, known object positions A,B and C with the plotted, positions as ‘a’,’b’ and ‘c’ on the sheet. The table is roughly, oriented by using compass or by eye judgement. Using, the alidade and sight the objects through the plotted, points respectively and draw back rays. Because of, rough orientation the rays will not pass through a single, point but will form a small triangle known as triangle error., By repeated trials, this triangle is eliminated so that the, three rays Aa, Bb and Cc pass through one point, which, is the required point (p). The position of point (p) is, estimated from the triangle of error by the application of, Lehmann’s Rules., , Construction: Draughtsman Civil - (NSQF Level -5): Related Theory for Exercise 2.3.51 - 52, , Copyright Free under CC BY Licence, , 63

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The triangle formed by joining the ground, points A, B and C is called the great triangle., The circle passing through these points is, called as the great circle., Lehmann’s Rules, – The distance of the point ‘P’ from each of the rays,, Aa,Bb and Cc is in proportion to the distance of A, B, and C from ‘p’ respectively., – When looking in the direction of each of the distant, points A, B and C the point ‘p’ will be found on the, same side of the three rays Aa, Bb and Cc i.e. it is, either to the left or to the right of each of the three, rays. (Fig 5 (ii), , – It follows from the above two rules that if the, instrument station ‘P’ lies outside the great triangle, ‘ABC’, the triangle of error falls outside ‘abc’ and the, required point ‘p’ is outside the triangle of error., (Fig5 (ii) and (iii), – Similarly if the station P lies with in the great triangle, ‘ABC’ the triangle of error falls inside the triangle ‘abc’, and the point ‘p’ must within the triangle of error, (Fig 5 (i), The above rules surface for the solution of the problem,, yet two more rules are given for assistance:, – When the station - point ‘p’ is outside the great circle,, the point’ p’ is always on the same side of the ray, drawn to the most distant point as the intersection (e), of other two rays. (Fig 5(ii)., – When the station point’ P’ is outside the great triangle, ‘ABC’ but inside the greatcircle i.e. within one of the, three segments of the great circle, formed by the sides, of the great triangles, the ray drawn towards the, middle point lies between the point p and the, intersection (e) of the other two rays (Fig 5 (iii)., Errors in plane tabling, The common sources of error in plane tabling are,, 1 Instrumental Error, 2 Errors or manipulation and sighting, 3 Errors of plotting., Instrumental Error, – The top surface of the board not being a perfect plane, – The edge of the alidade not being a straight line., – The sights of the alidade not being perpendicular to, its base., – The fittings of table and tripod being loose., – Error due to defective trough compass., Errors of manipulation and sighting, – The board not being horizontal, – The table not being accurately centered, – The table not being properly clamped, – The objects not being correctly sighted., – The alidade not being correctly centered on the station, point on the sheet., – The rays not being accurately drawn through the, station point., – The table not being correctly oriented., , 64, , Construction: Draughtsman Civil - (NSQF Level -5): Related Theory for Exercise 2.3.51 - 52, , Copyright Free under CC BY Licence

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Errors of Plotting, , Test, , – By using the good quality of paper and stretching it, correctly on the board., , •, , Set up and level the plane table over a station., , •, , Bringing the bubble in the central position by placing, of a spirit level on the table., , •, , Turn the table through 180º and check the bubble in, central or not., , •, , Then place the spirit level at 90º to the previous, position and check the bubble in the central and, repeat., , •, , If the bubble in central on reverse to the vertical axis, of the instrument. Therefore, the adjustment is, correct., , – By taking care in drawing and in the use of scales., Advantages and Disadvantages of plane table, surveying, Advantages, – It is the most rapid method., – Field notes are not required, hence the mistakes in, booking is eliminated., – The angles and linear measurement are not observed, since they are obtained graphically., , Adjustment, , – As plotting is done directly in the field; there is no, chances of omitting necessary measurements., , •, , If the bubble is not central position, the apparent error, (half of the error) by packing between the underside, of the board., , – Checking of plotted details can be done easily on the, spot itself., , •, , Repeat the same process till the buddle in central, after reversal in each case., , – The principles of intersection and resection are, conveniently used to avoid computation., , iii The Fiducial edge (or) ruling edge of the alidade, should be a straight line., , – The amount of office work is less., , – It is less costly than other types of surveys., – No great skill is required., , Test, •, , Select any two points on the drawing sheet at a, distance equal to length of the alidade., , – The absence of field notes is sometimes inconvenient,, if the survey is to be replotted to a different scale., , •, , Join these two points along the edge of the with fine, line., , – It is not used for large scale surveys and accurate, work., , •, , Reverse the alidade (End for end), , •, , Place the alidade at the end points and draw a line., , – The instrument is heavy and having many, accessories, being loose are likely to be lost, , •, , If the two lines are in inner line the alidade is a, corrected one., , – In rainy season and cold wind affect the progress of, survey., , Adjustment, , – This survey cannot be done in dense wooded areas., , If not, correct the edge by filling and again testing., , Disadvantages, , – Only day time can be availed for field and plotting, works when comparing other types of surveying., Testing and adjustment of plane table, , iv The axes of the spirit levels mounted on the, alidade should be parallel to the base of the, alidade., , i, , Test, , The board, , The upper surface of the board should a perfect plane., Test and adjustment, , •, , Place the alidade on the table., , •, , Bring the bubble of one of the levels of the alidade in, central by means of foot screws of the table., , •, , Check the straight edge in all the directions., , •, , Mark this position of the alidade., , •, , If the surface of the board is not perfectly plane,, remove the parts by sand papering or by planning., , •, , Lift and reverse the alidade into 180º and replace it, with in the mark., , •, , If the bubble is in central the adjustment is correct., , ii The surface of the board should be perpendicular, to the vertical axis of the instrument., , Construction: Draughtsman Civil - (NSQF Level - 5): Related Theory for Exercise 2.3.51 - 52, , Copyright Free under CC BY Licence, , 65

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Adjustment, , 3 The vertical circle must zero when the line of sight is, horizontal., , •, , If the bubble is not in central, bring the bubble in, central by adjusting the half the error by means of, level tube and other half by foot screws., , 4 The axis of the telescope level should be parallel to, the line of sight., , •, , Repeat the same procedure till the bubble is in centre., , General instructions while surveying plane table:, , •, , The same way test and adjust the second level tube., , v The sight vanes of the alidade should be, perpendicular to the base of the alidade., Test, In case of plain alidade, •, , Suspend a plumb line at a distance from the, instrument., , •, , Place the alidade on the levelled table. Observe the, sighting slit and vertical hair of the object vane appear, parallel to the plumb line., , Adjustment, •, , The following points are kept in mind while plane table:, The stations on the ground should be marked A, B, C, D, etc to be denoted by corresponding small letters a,b,c,d, etc. when plotting on the sheet., •, , The plane table should be turned, only on orientation., After orientation the board is clamped in position., , •, , While sighting objects, the table should be clamped, in position. Only the alidade should be moved on the, table to bisect the objects., , •, , The working edge of the alidade (fiducially edge) must, touching the plotted station point on the sheet while, sights are observed., , •, , It is advisable the alidade should be centred on the, same side of the station pin throughout the survey., keep the alidade on the left of station pin is more, idled., , •, , The drawing should be cleaned as for as possible., , If they are not in parallel to the plumb line, adjust by, tilting of the base of the sights. (sometimes packings, of the base of the sights also), , In case of telescopic alidade:, Adjustment, 1 The line of collimation should be perpendicular to the, horizontal axis of the telescope., 2 The horizontal axis must be parallel to the base of, the alidade., , The plane table is always placed in every, station which is parallel to the position, occupied at the first station, which is called, as the principle of plane table., Always orientation by back sighting is, preferred it is most reliable than magnetic, needle method., , Inking, finishing , colouring and tracing of plane table map, Objectives : At the end of this lesson you shall be able to, • explain about colouring of surveying symbols, • explain the importance of tracing, • state the technique/order of tracing a drawing, • state the different types of reproduction of drawings., Colouring: The chain lines are drawn with dash and dot, in crimson lake with 6 mm circles in red at the ends to, denote stations. The outline of the existing surface, features is shown in black while new works are, distinguished in red, railway lines, pipe railings, contours, are shown prussian blue, the centre lines are shown with, dash and dot in black, the dimensional lines are shown, with continuous lines at centre in crimson lake with, extremitres with black arrows., , – Before commencing colouring clean the drawing, , Erasing an ink line should be avoided as far as possible., , – Colouring commence from the top left hand corner, , In colouring following points should be in mind., , 66, , thoroughly with a piece of soft cloth., – Mix all colours light and not too dark., – If a large surface is to be coloured first moister the, surface with the help of a sponage or brush and take, off any super fluous moisture by placing a piece of, blotting paper over the moisture surface., , of the surface working from left to right and down, wards., , Construction: Draughtsman Civil - (NSQF Level - 5): Related Theory for Exercise 2.3.51 - 52, , Copyright Free under CC BY Licence

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The following colours are used for the features shown, against them., , The tracing cloth is made of thin transparent muslin fabric, (cotton) or plastic to provide a good and smooth surface, for inking purposes. It is taken rough side of the cloth, for ink work. Dust the surface with French chalk before, inking job. The tracing cloth is costlier than the paper. It, is available in roll and also in standard size of sheets., , No., , Features, , Colours, , 1, , Road metalled, Bridge, , Burnt sienna, , 2, , Road, unmetalled,, , Burnt timber, , Technique of Tracing / Order of tracing, Tracing in inking requires more attention to a, draughtsman/surveyor. Only the black ink (Indian ink, water proof) should be used for reproduction purpose., Inking should be done in the following order., , Barren land, 3, , Buildings, , Bench, Crimson lake, , 4, , Cultivated land, trees, , H green, , 5, , Compound wall, , Indigo, , – Full line circles and arcs starting from smallest, , 6, , Water, , Border edged, with prussian, blue., , – Circles and arcs, – Dotted circles and arcs starting from the smallest., – Regular curved lines and small arcs, , Importance of tracing:The drawings which are prepared, in the drawing office cannot be used directly in the site, as they may be gets spoiled and also there will not be, any copies for the future reference such as:, , – cannot be prepared another one, which is time, consuming at the cost of labour., , – Straight full lines verticals, horizontal and then inclined, – Straight dotted lines verticals, horizontal and then, inclined, – Centre lines, – Extension and dimension lines, – Arrow heads and dimensions, , – any modification needed cannot be carried out without, original., , – Section lines, , – only one copy is not sufficient enough as in shop floor,, the drawing has to be handled by many persons like, Craftsman/ Technician / Supervisors., , – Border, , Hence the drawings are traced on a transparent material., – Tracing Paper, – Tracing Cloth, The correct surface for pencil work is always the inner, surface., The tracing is drawn by pencil or black ink (water proof), with the crowquill pen/ ruling pen /Rotaring drawings pen., As crow quill and ruling pen are outdated, rotary pens of, various sizes are employed for tracing the drawing., The sizes of rotating pens are 1.2,1.0,0.8,0.6,0.5, 0.4,, 0.3, 0.2, 0.1 (all in mm indicates the thickness of line), The tracing is used like positive or negative for, reproduction of photo prints. The standard of tracing, paper is designated by their density i.e. weight per square, meter. It comes in rolls and in A4 & A3 Sheets. Generally,, for tracing purpose 90 gsm is used. Pencil lines may be, erased with rubber and for ink lines blade, erasing knife, or glass erasers may be used., , – Notes Titles (Guidelines may be drawn with pencil), , Duplication / Printing or drawings: The production of, more number of copies of the original drawings needed., Several economical process have been devised for, reproducing originals. Now -a-days different methods of, reproduction are available. The following are the different, reproducing process., Blue Printing Process: The blue printing process is the, simplest one of reproduction of drawings, drawn by, tracing. It is nothing but of photographic process in which, the tracing is the negative. The prints are done by, exposing the sensitized papers up on which the tracing, is kept in close surface contact and expose to the sunlight, or electric light. The fixture used for this purpose is known, a sun frame withstand., Fig 1a, b & c shows the sun frame, sun frame rotary type, and water tray., Fig 2 Folding drum type printing machine used for blue, printing and for ammonia printing process. In this, process of blue printing, the base of blue print is blue, and drawing lines are white in colour. After exposing in, the light paper is washed in clean water and dried in, shade. For washing water tray is used., , Tracing cloth: In some drawing tracing cloth is also, used, for preserving the tracing drawing for several years., Construction: Draughtsman Civil - (NSQF Level - 5): Related Theory for Exercise 2.3.51 - 52, , Copyright Free under CC BY Licence, , 67

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Ammonia Process: It is also similar to the blue printing, method. In this ammonia sensitized paper is used. The, paper is exposed in the same way of blue printing and, after exposing, the paper is developed in the ammonia, fumes raised from liquid ammonia. Chemical action, takesplace in the ammonia chamber, (Fig 3a, 3b & 3c), due to ammonia fumes. In this the background of the, print is white and the lines are blue., Now-a-days ammonia prints are widely used in the work, sites and for building plans., , 68, , Construction: Draughtsman Civil - (NSQF Level - 5): Related Theory for Exercise 2.3.51 - 52, , Copyright Free under CC BY Licence

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Construction, Related Theory for Exercise 2.4.53 & 2.4.54, Draughtsman Civil - Levelling and contouring, Principle of levelling - Auto level - Dumpy level- Tilting level, Objectives : At the end of this lesson you shall be able to, • describe the principle of levelling, • list the instruments required for levelling, • explain the parts of a level., Principle of levelling, Principle of levelling is to obtain a horizontal line of sight, from which vertical distances of the points above or below, this line are found. They are achieved with the help of a, level and a levelling staff respectively., Instruments required for levelling, Two instruments are required for levelling namely, 1 a level and, 2 a levelling staff, 1 The level, Level is an instrument used for furnishing a horizontal, line of sight. The essential part of a levelling instrument, are the following., 1 Levelling head, 2 Limb plate, 3 Telescope, 4 Bubble tube, 5 Tripod stand, 1 Levelling head: A levelling head consists of a tribrach, plate having three arms each carrying a levelling, screw in the ball and socket arrangement. These, levelling or foot screws are used to bring the telescope, bubble to the centre of its run. It is also an outer follow, conical socket into which fits the inner solid spindle, of the telescope, thus representing its vertical axis., The levelling head has an arrangement to fix the, instrument over the tripod., 2 Limb Plate: A limb plate is the one to which the, telescope is fixed by means of standards or supports., The lower portion of the limb plate has a solid spindle, which fits into the hollow socket of the levelling head., This spindle freely revolves in the outer socket and, locked at the bottom by means of a locking nut., 3 Telescope: A telescope is an essential component, part, which provides the basic line of sight for making, observations in the levelling operation. Telescope, consists of two tubes, one slides into the other and, fitted with lens and a diaphragm having cross hairs., Depending upon the arrangements made for the, , movement of this tubes, telescopes are classified into, two categories such as:, 1 External focusing telescope, 2 Internal focusing telescope, 1 External focusing telescope: In this type of, telescope, the body consists of two tubes, one of, which is capable of sliding axially within the other by, means of rack and pinion arrangements. This action, of sliding takes place by operating a focusing screw, available in the telescope. As one of this tube moves, out of the other and the length gets altered, the, telescope is known as external focusing telescope., 2 Internal focussing telescope: In this type of, telescope, out of two tubes on slides into the other,, the outer tube is fitted with both the eyepiece and, object glass at its either end. The other interior tube, carries a double concave lens, which moves inside, to and fro between the diaphragm and the object, glass. As the movement of inner tube is within the, outer one and the length remains same, the telescope, is known as internal focusing telescope., 3 Bubble Tube: A bubble tube consists of a sealed, curved glass tube set in a brass tube with plaster of, paris. It is nearly filled with alcohol or either or a, mixture of two, and the remaining space is occupied, by air bubble. The tube is graduated on both the, directions from its centre, which enables to centre, the bubble by operating the foot screws available in, the levelling head. One division on graduation is, equals to 2 mm. The bubble tube is attached to the, top of the telescope by means of capstan headed, nuts, it is also otherwise known as ‘level tube’ and, used for levelling up the instrument. In levelling up, operation bubble in the bubble tube is brought to the, centre (highest point) and a line tangential to the, curvature of the tube at that point is known as bubble, line. The bubble line is horizontal when the bubble is, in the centre., 4 Tripod Stand: A tripod stand is the one, which, supports the instrument when in use. It consists of, three legs either solid or framed one. These legs are, made of mahogany wood and its lower end is fitted, with a pointed steel shoes so that it can be firmly, pressed into the ground. The tripod should be rigid, and if it has any looseness it affects the position of, instrument. The tripod head, as its top carries external, threads to which internal threads of the instrument is, fitted., 69, , Copyright Free under CC BY Licence

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Types of Levels, , 1 The dumpy level, , The Y level is a very delicate instrument. It consists of, many loose and open parts, which are liable to frictional, wear. The telescope can be removed from the Y, supports, and reversed end for end. It can also be, revolved about its longitudinal axis in the Ys., , 2 The wye or Y level, , 3 The cooke’s reversible level, , There are various types of levels, viz., , 3 The cooke’s reversible level, The cooke’s level combines good features of both the, dumpy and Y levels. By slackening the stop screw the, telescope can be rotated about its longitudinal axis in its, sockets and can also be withdrawn from its sockets and, replaced and for end. (Fig 3), , 4 The cushing’s level, 5 Tilting level and, 6 The automatic level, 1 The dumy level (Fig 1), , 4 The cushing’s level, , The dumpy level is simple, compact, and stable. The, telescope is rigidly fixed to its supports and, therefore,, can neither be rotated about its longitudinal axis, nor can, it be removed from its supports. It has greater stability of, adjustments than the Y level., 2 The Wye or Y level (Fig 2), , In the case of the crushing’s level, the telescope can, neither be removed from its socket, nor can it be revolved, about its longitudinal axis. However, the eye-piece, (carrying with it the diaphragm) and the object glass are, removable, and can be interchanged to reverse the, telescope end for the end, both collars being exactly alike., Similarly, the eye-piece end can be rotated in its fitting., 5 The Modern (Tilting) Level, In the case of this instrument the telescope has a small, motion about a horizontal axis. It is, therefore, known, as the tilting level. The main peculiarity of this level is, that the vertical axis need not be truly vertical, since the, line of collimation is not perpendicular to it. The line of, collimation, is however, made horizontal for each pointing, of the telescope by means of a tilting screws. It is mainly, designed for precise levelling work. (Fig 4), 6 The automatic level, The automatic level also designated as self aligning level., The fundamental difference between the self alignment, level and the classic spirit level is that, in the former the, line of sight is no longer levelled manually using a tubular, spirit level but is levelled automatically. Within a certain, tilt range this is achieved by an inclination compensating, device called tilt compensator suspended like a, pendulum and inserted in the path of light rays through, the telescope. (Fig 5), , 70, , Construction: Draughtsman Civil - (NSQF Level -5): Related Theory for Exercise 2.4.53 & 54, , Copyright Free under CC BY Licence

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Advantages of using auto level, 1 Operational comfort: Measurement is not fatiguing, Control of level which is so try to the eyes, nerves, and hands is eliminated. The automatic level does, not require any protection from the sun., 2 High precision: Mean elevation error on invar staff, graduated to 5mm divisions varies between+ 0.5 to, 0.8 mm per km of forward and backward levelling., 3 High speed: Time required for levelling work is about, 50% of that required with ordinary level. This is an, advantage where work is to be carried out in a limited, time. Errors due to settlement are thereby eliminated., 4 Freedom for errors: The accuracy of a single, measurement is increased by an erect telescope, image, the levelling rods with erect figures in proper, sequence, freedom from fatigue, the possibility of, forgetting to get the bubble in the centre as well as, simple and quick means of operation., 5 Freedom from external influences: The external, influences like marshy ground, rain, wind, sun, loss, of light due to clouds, magnetic fields, continuous, vibrations, transport vibrations, have no influence of, the levelling work., 6 Range of application: The level can be used on, medium and large sized projects and setting Bench, Marks of the 3rd to 1st order., , Construction: Draughtsman Civil - (NSQF Level - 5): Related Theory for Exercise 2.4.53 & 54, , Copyright Free under CC BY Licence, , 71

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Construction, Related Theory for Exercise 2.4.55 & 2.4.56, Draughtsman Civil - Levelling and conturing, Levelling staff - Its Graducation & Type, Objectives : At the end of this lesson you shall be able to, • describe levelling staff, • explain the classification of levelling staff, • explain the constitution of various types of levelling staff., i, , Levelling Staff, A levelling staff is a straight, rectangular wooden rod, graduated into meters and smaller divisions. The bottom, of the rod (Levelling staff) represents zero reading. The, levelling staff is used to determine the amount of height, of depth by which the point is above or below the line of, sight. It is usually made up of well-seasoned wood., The graduations on the levelling staves are such that a, metre length is divided into 10 main divisions of one vision, equals to 10 cm or 1 decimetre. Again this one main, division is sub divided into 20 more strips of alternate, black and white in colour of width 5 mm. Hence the, smallest value, which we can observe with the levelling, staff is 5 mm, therefore the least count is 0.005m. Main, divisions in each metre length is marked with the, numerals 1 to 9 in black colour. The readings, corresponds to metre’s length is marked with numerals, 1,2,3 …. etc. in red colour.These numerals are marked, in such a way that its top is coinciding with the end of, that graduation. For convenience the numbers like 5, and 9 are marked as V and alphabet N respectively, to, avoid confusion with the numerals 2 and 6, as the staff, is invertedly seen when viewed through the telescope, Types of Staves, The levelling staves are mainly classified into two, categories based on the method of observation as, follows:, 1 Self reading staff, 2 Target staff, Self reading staff, Self reading staff is the one, by which the readings are, observed directly by an observer (instrument man) who, views through the telescope. These staves are further, classified based on the construction as follows:, i, , Solid staff, , ii Folding staff, iii Telescopic staff, iv Invar staff, , Solid Staff: A solid staff is one, which is made of, seasoned wood either Pine or Deodar. It is usually, 3m long in one piece length. It has the cross section, of 75 mm in width and 25mm to 40 mm in thick. Due, to the absence of range or socket on these staves, greater accuracy is achieved. On the other hand it is, inconvenient to carry them in the field. Its use is, restricted only to precise levelling., , ii Folding Staff: Folding staff is the one, which is also, made of seasoned wood and available in two pieces, of length equals to 2 m. The total length of this staff, is 4 m. These two pieces are connected by means of, a hinge. The folding staff has the cross section of, 75 mm in width and 18 mm in thick. The joint provided, in the folding staff in such that., a The staff may be folded to a length of 2 m when it, is not in use., b The pieces may be easily detachable from one, another for easy handling., c When the two pieces are locked together the staff, is quite rigid at the joint and perfectly straight., The foot of the staff is provided with a brass cap to avoid, wear and tear due to usage., iii Telescopic staff: A telescopic staff is the one which, consists of three pieces. One slide into the other. It, has the maximum lengths of 4 m or 5 m when fully, extended. The 4 m telescopic staff has a top solid, piece of length 1.25m, which slides into the cental, box of 1.25 m length, which is turn slides into the, lower box of length 1.5 m. Brass spring catches are, provided to hold the extensions in position., iv Invar Staff: The invar staff is also 3 m long. An invar, band is fitted to a wooden staff. The band is graduated, to millimeters. It is used for precise levelling work., 2 Target Staff: A target staff is the one by which the, readings are observed by the staff man has the target, is viewed by the instrument amn. This target staff is, provided with a movable target. The target is provided, with nernier, which is adjusted by the staff man as, directed by the instrument man until its centre line, coincides with the horizontal cross hair in the, diaphragm. The readings are then observed and, recorded by the staff man. This type of staves are, used when the sights are long., , 72, , Copyright Free under CC BY Licence

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Construction: Draughtsman Civil - (NSQF Level - 5): Related Theory for Exercise 2.4.55 & 56, , Copyright Free under CC BY Licence, , 73

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Construction, Related Theory for Exercise 2.4.57 - 2.4.59, Draughtsman Civil - Levelling and countouring, Holding of levelling staff - Temporary adjustments, Objectives : At the end of this lesson you shall be able to, • hold and read levelling staff, • explain the various adjustments of level, • explain the temporary adjustments of level, • state the instruction for a staff man and level man, • explain about hand signals used during observations., Holding the staff (Fig 1), , When the graduations on the staff are inverted they look, erect when seen through the telescope. The staff should, be read upwards., If the target staff is used, the procedure is the same, except that the target is set by the staff man as directed, by the instrument man, and the reading is then taken, and recorded by the staff man., Adjustments of the level, , Utmost care should be taken in holding the staff truly, vertical while the reading is being taken. To hold the staff, in a vertical position, the staff man stands behind the, staf, heels together, with the heel of the staff between, his toes, and holds it between the palm of his hands at, the height of his face. If it is not vertical, the reading will, be too great., , There are two types of adjustments:, 1 Permanent, and, 2 Temporary, Permanent, , In precise levelling, the staff is equipped with a folding, circular level or a pendulum plumb bob to make it plumb, while in ordinary levelling, the staff is waved slowly, forward, i.e., towards the level, and backward, i.e., away, from the level, and the lowest reading taken to avoid, these errors., , The permanent adjustments are made to establish the, fixed relationship between the fundamental lines of an, instrument. Once made, the permanent adjustments last, for a long time depending on the type of the instrument., The temporary adjustments are made at each set up of, the instrument before starting to take the various staff, readings., , Reading the staff, , Temporary adjustments of the level, , The staff readings should be taken in the following order:, , These are performed to make the axis of rotation vertical, and to eliminate the parallel every time when the, instrument is shifted and set up in a new position. It is, also known as “setting up” of the instrument and is made, in the following steps:, , i, , Having set up and levelled the instrument carefully,, direct the telescope towards the staff held vertically, on the staff station and focus it., , ii Always bring the staff between the two vertical hairs,, and always use the portion of the horizontal crosshair between them in reading staff as the horizontal, cross-hair may be slightly inclined. By means of the, vertical hairs, the level man can see if the staff is out, of plumb (sloping) sideways. If there be only one, vertical hair, a reading should be taken at the, intersection., iii Observe if the bubble is central. If not, centre it by, using one of the foot screws most nearly in line with, the telescope, and note the reading at which the, horizontal cross-hair appears to cut the staff. First, note the red figure, then the black figure, and finally, count the spaces. Record the reading., , 1 Fixing the instrument on stand, 2 Levelling up the instrument, 3 Focussing, Fixing level with tripod stand, The tripod stand is placed at the required position with, its legs well apart, and pressed firmly into the ground., The level is fixed on the top of the tripod stand according, to the fixing arrangement provided for that particular level., It should be remembered that the level is not to be set, up at any station or point along the alignment., , 74, , Copyright Free under CC BY Licence

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Levelling up the instrument: It is done approximately, by legs and correctly by the levelling screws., , ii Focussing the object-glass for bringing the image of, the object into the plane of the diaphragm., , Levelling by legs: Bring all the foot-screws in the centre, of their run and place the instrument in a desired position, at a convenient height with the tribrach plate as nearly, horizontal as possible. Fix any two firmly into the ground, by pressing them with hand and turn the telescope to be, nearly parallel to the line joining the feet of these two, legs., , Focussing the eye piece, , Then move the third leg to right or left and in or out to, bring the long and cross bubbles respectively in their, central positions much time is saved if nearly all the, levelling is done by the tripod legs., Levelling by foot-screws: Place the telescope parallel, to any pair of the foot-screws and bring the long bubble, to the centre of its run by turning these screws equally, either both inwards or both outwards. To move the bubble, to the right turn the screws inwards and to move it to the, left turn the screws outwards (right in and left out)., Then turn the third foot screw to bring the cross bubble, to its central position. Repeat this until both the bubbles, are centered. If the instrument is in permanent, adjustment, then the bubbles will traverse for all directions, of the telescope., i, , The instrument should, as far as possbile, be set up, on a solid ground to avoid its settlement in the course, of observation in a setting. However, if such stable, ground is not available, the tripod legs should be, pressed firmly into the ground., , ii While setting the instrument on a pucca floor, the, shoes of the tripod should, as far as possible, be, placed in the joints to prevent the legs from spreading, out through slipping., iii When setting on a sloping ground, two legs should, be kept down slope and the third up slope., , This operation is done to make the cross-hairs appear, distinct and clearly visible. The following steps are, involved:, 1 The telescope is directed skywards or a sheet of white, paper is held in front of the objective., 2 The eye piece is moved in or out till the cross-hairs, appear distinct., Focussing the objective, This operation is done to bring the image of the object in, the plane of the cross-hairs. The following steps are, involved:, 1 The telescope is directed towards the staff., 2 The focussing screw is turned until the image appears, clear and sharp., Instruction for a staff man, -, , The staff should be vertical and upright., , -, , The staff should be held on stable ground., , -, , When working with telescopic staff care should be, taken to the extend all the parts by the spring catches, , -, , When using aluminium staff extra care should be, taken while extending near electric posts., , Instruction for a level man, Levelling should always commence from a permanent, BM and end on a permanent BM, The level should be setup on a firm ground and at a, place where maximum number of sights can be taken., To avoid errors due to imperfect adjustment of the, instrument, the instrument should be setup approximately, mid way between the change points., Move the telescope laterally by gentle tapping to bring, the staff exactly between the vertical hairs and focus it., While looking through the telescope, the staff is seen, inverted. Therefore, it should always be read from above, downwards and not upwards., , Focusing, , When a group of surveyors are working, one’s own staff, should be carefully recognized., , This is done in two steps viz., , Following hand signals should be observed, , i, , Hand signals during observations, , Focussing the eye-piece for distinct vision of the, cross-hairs at diaphragm, and, , When levelling is done at construction site located in, busy, noisy areas, it becomes difficult for the instrument, , Construction: Draughtsman Civil - (NSQF Level -5): Related Theory for Exercise 2.4.57 - 59, , Copyright Free under CC BY Licence, , 75

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man to give instructions to the man holding the staff at, the other end through the vocal sounds. In that case,, the following hand signals are found to be useful. (Table, 1 and Fig 3), , Table 1, Signal, , Message, , a, , Movement of left arm over 90, , Move to my left, , b, , Movement of right arm over 90, , Move to my right, , c, , Movement of left arm over 30, , Move top of staff to my left, , d, , Movement of right arm over 30, , Move top of staff to my right, , e, , Extension of arm horizontally and moving, , Raise height of peg or staff, , hand downwards, f, , Extension of arm horizontally and moving, , Lower height of peg or staff, , hand downwards, g, , Extension of both arms and slightly, , Establish the position, , thrusting downwards, h, , Extension of arms and placement of, hand on top of head, , Return to me, , Level field book, Objectives: At the end of this lesson you shall be able to, • describe the term level field book and its various forms, • explain the point to be observed while recording a level book, • compute the reduced levels of the staff stations., 1 Height of collimation method, , Form of a level book, Whenever the levelling operation is carried out and, number of observations are taken in the field, they are, to be entered in a note book called a ‘Level Book.’ Each, page of this level book has the following columns which, helps to enter the readings and reduce the levels. Left, side of each page consists of column corresponds to, the staff readings and reduction of levels. Right side of, each page consists of columns for remarks to note down, the details of bench marks for which the readings have, been taken, Two forms of level book, Page of a level book, 76, , B.S., , I.S., , F.S., , H.I. or H.C., , R.Ls., , Remarks, , ___________________________________________________, 2 Rise and fall method, B.S., , I.S., , F.S., , H.I. or H.C., , R.Ls., , Remarks, , Apart from the above, details such as name of work,, instrument number, name of the surveyor etc. are to be, furnished in each page of a level book., Name of the work………................…. Date……………., Name of the Surveyor……........ Instrument No…………, , Construction: Draughtsman Civil - (NSQF Level -5): Related Theory for Exercise 2.4.57 - 59, , Copyright Free under CC BY Licence

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Points to be observed while booking readings in a, level book, 1 Every horizontal line in a page of level book represents, one station only., 2 Readings are to be entered in the respective columns, in the order of observation., 3 First reading in a page of level book should be Back, sight and the last reading should be Fore sight., 4 If the last entry happens to be an intermediate sight,, enter it in the Fore sight column of that page and the, same is repeated in the Back sight column of the next, page, 5 Fore sight and Back sight reading of a change point, should be entered in the same horizontal line, 6 R.L. of line of collimation or height of collimation, should be written in the same horizontal line, corresponds to its back sight., 7 Details of staff station should be written briefly in the, remarks column., 8 All the readings should be entered in ink only., 9 When observations of a work is continued in many, number of pages, no reduction of levels in the next, page is done unless the previous page is checked., , In general height of collimation method is given by, Height of collimation = R.L. of a BM + Back sight reading, R.L. of other staff stations = Height of a collimation –, I.S./F.S. readings, After the completion of the above calculation it can be, checked for its correctness by an Arithmetical check., Arithmetical check, Σ BS – Σ FS = Last R.L. – First R.L., Rise and fall method, In this method the difference of level between the two, consecutive points is obtained by comparing the staff, readings taken from the same set up of the instrument., This difference indicates whether the next point is at Rise, or Fall than the previous one. If the staff reading is greater,, the point is at Fall. If the staff reading is smaller, the, point is at Rise. The R.L. of any point is determined, by either adding or subtracting the respective rise or fall, values from the R.L. of the previous point. The above, procedure is repeated until the last point is reached., In general Rise and Fall method is given by:, , Reduction of levels, , First reading – Second reading = ± Rise / Fall., , Reduction of levels is the process of calculating the R.L., for various points to which observation are taken. There, are two methods of calculating the RL. such as:, , (When the second reading is subtracted from the first, one, the positive result means the rise and the negative, result means fall), , 1 Height of collimation method, , R.L. of any point = R.L. of the previous point ± Rise / Fall, of that point (use positive sign for rise and negative sign, for fall)., , 2 Rise and fall method, Height of collimation method, In this method height of collimation i.e., the R.L. of line, of collimation for each set up of the instrument is obtained, by adding the back sight reaching to the R.L. of a bench, mark on which back sight is taken. The R.L. of line of, collimation is taken as a reference and the R.L. for, various other points from that set up of the instrument is, obtained by subtracting their respective staff readings, such as Intermediate sight of Fore sight., When the instrument is shifted to a new station, the height, of collimation for that set up is obtained by adding the, staff reading taken on a change point (i.e., the point of, which the last observation is taken from the previous, instrument station) to its R.L. The R.L. of the other staff, stations observed from the new station are obtained by, subtracting their respective staff readings from its height, of collimation. This process is repeated until the last, point is reached., , After the completion of the above calculations it can be, checked for its correctness by an Arithmetical check., Arithmetical check, This Arithmetical check also provides check only for, calculations not the result., In this the differences between, the sum of B.S. and F.S., the sum of rise and Fall and the last R.L. and first R.L., should be equal., Σ .B.S. – Σ F.S. = Σ Rise - Σ Fall = Last R.L - First R.L, which depends upon the respective values., This method provides a complete check on the, intermediate sight also., , Construction: Draughtsman Civil - (NSQF Level - 5): Related Theory for Exercise 2.4.57 - 59, , Copyright Free under CC BY Licence, , 77

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Comparison of line of collimation method with rise and fall method, S.No, , Line of collimation method, , Rise and fall method, , 1, , It is more rapid and the computation is easier, and faster., , Computation is labourious and time consuming,, because each and every staff reading is compared., , 2, , It is simple method used for reduction in, profile levelling., , This method is used where more accuracy is, required., , 3, , There is no check in reduction of levels for, intermediate stations., , There is a complete check for all intermediate, , 4, , Errors if any commited in reduction of levels, for intermediate stations, cannot be deducted, , Errors can be noticed and rectified for intermediate, stations., , Problems on levelling, Objectives: At the end of this lesson you shall be able to, • determine the reduced levels of the station points by height of collimation method, • determine the reduced levels of the station points by rise and fall method., Problems in levelling, , The instrument was shifted after the fourth reading and, the first reading was taken on BM with RL = 100.00. rule, out a page of level book and work out the RL of all points, by collimation method and rise and fall method., , Example 1, Following consecutive readings were taken on points 1, to 7 along a line., 0785, 1.326, 2.538, 3.435, 1.367, 2.328, 1.234, 1.657., , Collimation method, Solution, Station, , Readings, B.S., , 1, , I.S., , Height of lnstrument, , RLs, , 100.785, , 100.00, , BM, RL = 100, , F.S, , 0.785, , 2, , 1.326, , 99.459, , 3, , 2.538, , 98.247, , 4, , 1.367, , 3.435, , 98.717, , 97.350, , 5, , 1.238, , 96.389, , 6, , 1.234, , 97.483, , 7, Total, , 1.657, 2.152, , Remarks, , 97.060, , 5.092, , H.I. = R.L. + B.S. = 100.00 + 0.785 = 100.785, , Arithmetical check, , R.L. = H.I. – I.S / F.S. = 100.785 – 1.367 = 99.459, , Σ B.S. – Σ F.S. = 02.152 – 5.092 = -2.940, Last R.L. – First R.L. = 97.060 – 100.00 = 2.940 Ans., , 78, , Construction: Draughtsman Civil - (NSQF Level -5): Related Theory for Exercise 2.4.57 - 59, , Copyright Free under CC BY Licence

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solution for the above problem in rise and fall method, Station, , Readings, B.S., , 1, , Rise, , I.S., , Fall, , RL, , F.S, , 0.785, , 100.00, , BM, RL = 100, , 2, , 1.326, , 0.541, , 99.459, , 3, , 2.538, , 1.212, , 98.247, , 0.897, , 97.350, , 0.961, , 96.389, , 4, , 1.367, , 3.435, , 5, , 2.328, , 6, , 1.234, , 7, , 1.094, , 2.152, , Σ F.S, , 5.092, , CP, , 97.483, , 1.657, , ΣB, , Remark, , 0.423, 1.094, , 97.060, , 4.034, , Arithmetical checks, , Example 2, , Σ B.S. – Σ F.S. = 2.152 – 5.092 = -2.940, , Problem 2, , Σ Rise – Σ Fall = 1.094 – 4.034 = -2.940, , The readings are entered in the page of level field book, as shown below. Reduce the levels by both the height of, collimation method and Rise and Fall method, given the, R.L. of a B.M. 1 as 200.000 m. Apply the check., , Last R.L. – First R.L. = 97.060 – 100.00 = 2.940 Ans., , Station, , B.S., , 1, , 1.430, , I.S., , 2, , 2.015, , 3, , 1.005, , 4, , 3.370, , 5, , 2.975, , 6, , 1.415, , 7, , F.S., , R.L., , Remarks, , 200.000, , B.M. 1, , 0.400, , C.P., , 0.695, , B.M. 2, , Solution: By Height of collimation method, Station, , B.S., , 1, , 1.430, , I.S., , F.S., , Height of collimation, , R.Ls., , Remarks, , 201.430, , 200.00, , B.M. 1, , 2, , 2.015, , 199.415, , 3, , 1.005, , 200.425, , 4, , 3.370, , 0.400, , 204.400, , 201.030, , 5, , 2.975, , 201.425, , 6, , 1.415, , 202.985, , 7, , 0.695, , 203.705, , C.P., , B.M. 2, , Construction: Draughtsman Civil - (NSQF Level -5): Related Theory for Exercise 2.4.57 - 59, , Copyright Free under CC BY Licence, , 79

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General rule in height of collimation method is, , R.L. of a point 5 = 204.400 - 2.975 = 201.425, , Height of collimation = R.L. of B.M. + B.S. on that B.M., , 6 = 204.400 - 1.415 = 202.985, , R.L. of any point = Height of collimation - I.S. / F.S. of, that point., , R.L. of B.M.2 (7) = 204.400 - 0.695 = 203.705, Arithmetical check, , ∴ Height of Collimation for the 1st set up, , ∑B.S. = 1.430 + 3.370 = 4.800, , = 200.00 + 1.430 = 201.430, R.L. of a point 2 = 201.430 - 2.015 = 199.415, 3 = 201.430 - 1.005 = 200.425, , ∑F.S. = 0.400 + 0.695 = 1.095, ∑B.S. - ∑F.S. = 4.800 = 1.095 = 3.705, Last R.L. - First R.L. = 203.705 - 200.000 = 3.705, , R.L. of C.P. (4), , = 201.430 - 0.400 = 201.030, , Height of collimation for the 2nd set up, , ∑B.S. - ∑ F.S. = last R.L. - First R.L., Hence OK, , = 201.030 + 3.370 = 204.400, By rise and fall method, Station, , B.S., , 1, , 1.430, , I.S., , 2, , 2.015, , 3, , 1.005, , 4, , 3.370, , F.S., , Rise, , Fall, , 0.585, , 0.400, , R.Ls., , Remarks, , 200.00, , B.M. 1, , 199.415, , 1.010, , 200.425, , 0.605, , 201.030, , 5, , 2.975, , 0.395, , 201.425, , 6, , 1.415, , 1.560, , 202.985, , 0.720, , 203.705, , 7, , 0.695, , General rule, , 5 = 201.030 + 0.395 = 201.425, , Difference in level between the successive points, , 6 = 201.425 + 1.560 = 202.985, , 1st reading - 2nd reading = ± Rise / Fall., R.L. of any point = R.L. of the previous point ± Rise/Fall, Difference in levels for station 2, = 1.430 - 2.015 = - 0.585 (Fall), For Station 3 = 2.015 - 1.005 = + 1.010 (Rise), 4 = 1.005 - 0.440 = + 0.605 (Rise), 5 = 3.370 - 2.975 = + 0.395 (Rise), , C.P., , B.M. 2, , 7 = 202.985 + 0.720 = 203.705, Arithmetical check, , ∑ B.S. = 1.430 + 3.370 = 4.800, ∑ F.S. = 0.400 + 0.695 = 1.095, ∑B.S. - ∑. F.S. = 4.800 - 1.095 = 3.705, ∑ Rise = 1.010 + 0.605 + 0.395 + 1.560 + 0.720 + 4.290, , 6 = 2.975 - 1.415 = + 1.560 (Rise), 7 = 1.415 - 0.695 = + 0.720 (Rise), R.L. of a station point 2 = 200.00 - 0.585 = 199.415, 3 = 199.415 + 1.010 = 200.425, , ∑Fall = 0.585, ∑ Rise - ∑ Fall = 4.290 - 0.585 = 3.705, Last R.L. - First R.L. = 203.705 + 200.00 = 3.705, , 4 = 200.425 + 0.605 = 201.030, , ∑ B.S. - ∑ F.S. = ∑ Rise - ∑ Fall = Last R.L. - First R.L., Hence OK., 80, , Construction: Draughtsman Civil - (NSQF Level -5): Related Theory for Exercise 2.4.57 - 59, , Copyright Free under CC BY Licence

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Construction, Related Theory for Exercise 2.4.60, Draughtsman Civil - Levelling and contouring, Types of levelling, Objectives : At the end of this lesson you shall be able to, • name the various types of levelling, • explain simple levelling, • explain differential levelling, • Complete the reduced levels of points., According to the method adopted, levelling may be, classified into two, , Differential levelling (Fig 2), , 1 Direct levelling, 2 Indirect levelling, Direct levelling, The method of levelling in which the relative heights of, points are found out by some direct observation is called, direct levelling., , Differential levelling is adopted when, i, , the points are a great distance apart,, , Various methods of direct levelling:, , ii the difference of elevation between the points in large, , 1 Simple levelling, , iii there are obstacles between the points., , 2 Differential levelling., , The method is also known as compound levelling or, continuous levelling. In this method, the level is set up, at several suitable positions and staff readings are taken, at all of these., , 3 Reciprocal levelling, 4 Profile levelling, i, , Longitudinal sectioning, , ii Cross Sectioning, 5 Fly levelling, 6 Check levelling, Simple levelling (Fig 1), , Suppose it is required to know the difference of level, between A and B, the level is set up at points O1,O2, O3,, etc. After temporary adjustments, staff readings are, taken at every set up. The points C1, C2 and C3 are, known as change points. Then the difference of level, between A and B is found out. If the difference is positive,, A is lower than B. If it is negative, A is higher than B., Knowing the R.L. of A that of B can be calculated., Problems in levelling (Fig 3), , When the difference of level between two points is, determined by setting the levelling instrument midway, between the points, the process is called simple levelling., Suppose A and B are two points whose difference of, level is to be determined. The level is set up at O, exactly, midway between A and B. After proper temporary, adjustment, the staff readings on A and B are taken. The, difference of these readings gives the difference of level, between A and B., , 81, , Copyright Free under CC BY Licence

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Example 1, , Inverted, , In a simple levelling the Back sight takn from a point A of, R.L. 100.000 is 2.850 m and Foresight taken from point, C is 0.520 m find., , When the BM or staff station is above the line of sight, , i, , The difference of level between the A and C, , ii The R.L. at point C, Solution, i, , The difference of level between A and C, = 2.850 – 0.520, , Height of collimation, , In this case, it occurs when the underside of a string, course or sunshade is made a Benchmark, or when the, elevation of the underside of girder, and arch or the, beam is to be determined. It is easy to hold the staff, inverted and the reading being negative, is entered in, the level book with a minus sign. To avoid confusion, “Staff inverted” should be written in the Remarks column, against the entry of the reading., Problems in inverted level, , =, , 2.330, , =, , R.L at point A +, B.S. taken from point A, , =, , 100.000 + 2.850, , =, , 102.850 m, , =, , Height of collimation –, Foresight reading at C, , =, , 102.850 – 0.520, , =, , 102.330 m, , Example 1, The R.L of the floor is 100.595 m and staff reading on, the floor is 1.790m. The reading on the staff held upside, down against the underside of the tee beam is 3.890m., Find the height of the beam above the floor level., , ii R.L. at point C, Solutions (Fig 4), i, , Sketch, , ii Tabulation, , Exercise 1, The back sight reading at A is 3.560m and the foresight, reading at B is 2.860m Find the difference in level of A, and B., Exercise 2, The back sight reading on a staff held vertically on a, bench mark whose R.L. 100.000 was 2.960 m and the, foresight on the staff held vertical on a rail was 0.880m, and the reduced level of the rail., , Back Sight, , Inter Sight, , Foresight., , 1.790, , HCL, , Reduced Level, , 102.385, , 100.595, , Staff reading on the floor (B), , 106.275, , Inverted Staff reading at, bottom of tee beam, , -3.890, , Remarks, , R.L. of the underside of the tee beam, , Calculation, R.L of the floor, , = 100.595 m, , = 102.385, , Staff reading on the floor (B) = 1.790m, , = 102.385 – (-3.890), , ∴ Height of collimation at A, , = 106.275 m, , = R.L of the floor +, Staff reading on the floor, = 100.595 + 1.790, , Height of the tee beam above the floor level, = 106.275 – 100.595, = 5.680m (Ans), , = 102.385 m, 82, , Construction: Draughtsman Civil - (NSQF Level -5): Related Theory for Exercise 2.4.60, , Copyright Free under CC BY Licence

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Exercise 1, , Problems in differential levelling, , Find the height of the tee beam above the floor level, , Example, , from following data. R.L. of the floor level = 100.000,, Staff reading on the floor = 1.150 reading on the staff, held inverted the bottom touching the underside of tee, beam = 3.450m, , Tabulate and enter the following staff reading were taken, in the differential levelling and also find the R.L. of all the, points. The first reading was taken on a B.M of R.L, 100.000 by., , Exercise 2, , i, , HCL method (height of collimation method), Apply usual check, , The back sight reading on a staff held vertical on a, benchmark whose R.L. is 501.00 m is 1.580 m and the, foresight on a staff held vertically inverted against a beam, is 3.580 m Find the reduced level of the beam., , 2.045, 2.680, 2.860, 2.120, 2.975 and 2.860, , Solution, Height of Collimation Method, Back sight, , Inter sight, , Foresight, , HCL, , Reduced Level, , 102.045, , 100.00, , Reading taking on B.M, , 2.680, , 99.365, , Point 1, , 2.860, , 99.185, , Point 2, , 2.120, , 99.925, , Point 3, , 2.975, , 99.070, , Point 4, , 99.185, , Point 5, , 2.045, , 2.860, 2.045, , Remarks, , 2.860, , Calculation, Height of collimation, , R.L of point 1, , R.L. of point 2, , R.L. of Point 3, , R.L. of point 4, , =, , HCL – IS. reading on, point 4, , =, , 102.045 – 2.975, , =, , 99.070, , =, , HCL – F.S. reading on, point 5, , =, , R.L. of B.M + Back, sight, , =, , 100.000 + 2.045, , =, , 102.045 m, , =, , HCL – I.S reading on, point 1, , =, , 102.045 – 2.860, , =, , 102.045 – 2.680, , =, , 99.185, , =, , 99.365, , Arithimetic Check, , =, , HCL – I.S. reading on, point 2, , =, , 102.045 – 2.860, , The difference between the sum of back sights and the, sum of fore sights should be equal to the difference, between the last and the first RLS., , =, , 99.185, , ∑ B.S – ∑ .F.S, , = Last R.L – First R.L, , =, , HCL – I.S. reading on, point 3, , 2.045– 2.860, , = 99.185 – 100.000, , =, , 102.045 – 2.120, , =, , 99.925, , R.L. of point 5, , = - 0.815, , Construction: Draughtsman Civil - (NSQF Level -5): Related Theory for Exercise 2.4.60, , Copyright Free under CC BY Licence, , 83

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Rise and fall method, B.S, , I.S., , F.S, , Rise, , Fall, , 2.045, , 100.00, , Readiong taken on B.M, , 0.635, , 99.365, , Point 1, , 2.860, , 0.180, , 99.365, , Point 2, , 99.925, , Point 3, , 99.070, , Point 4, , 99.185, , Point 5, , 0.740, , 2.975, , 2.860, , 0.855, 2.860, , 0.115, , 0.855, , 1.670, , Calculation, i, , Remarks, , 2.680, , 2.120, , 2.045, , Reduced Level, , R.L. of point 3, , = R.L of point 2 +, Rise of point 3, , B.S. on B.M. – I.S. on point 1, , = 99.185 + 0.740, , = 2.045 – 2.680, , = 99.925, , = 0.635 (Fall), , R.L of point 4, , = R.L. of point 3 –, Fall of Point 4, , ii I.S on point 1 – I.S.on point 2, , = 99.925 -0.855, , = 2.680 – 2.860, , = 99.070, , - 0.180 (Fall), R.L of point 5, , = R.L of point 4 +, Rise of point 5, , iii I.S. on point 2 – I.S on point 3, = 2.860 – 2.120, , = 99.070 + 0.115, , = 0.740 (Rise), , = 99.185, Arithmetic Check, , iv I.S. on point 3 – I.S. on point 4, ∑B.S. -∑ F.S., , = 2.120 – 2.975, = 0.740 (Rise), , 2.045-2.860, , v I.S on point 4 – F.S. on point 5, = 2.975 – 2.860, , -0.815, , =, , ∑Rise – ∑fall, , =, , Last R.L –, , =, , 0.855 – 1.670, , =, , 99.185 –100.000, , =, , - 0815 - 0.815, , First R.L, , = 0.115 (Rise), Exercise 1, R.L of point 1, , = R.L of B.M – Fall of point 1, = 100.000 – 0.635, , Tabulate and enter the following reading on the level field, book and find the reduced levels of the points., , = 99.365, i, R.L. of point 2, , 84, , = R.L. of point 1 – Fall of, point 2, , Height of collimation method, , ii Rise and fall method, , = 99.365 – 0.180, , 2.200, 2.430, 2.400, 2.120, 2.900 and 2.750, , = 99.185, , Apply usual check, , Construction: Draughtsman Civil - (NSQF Level -5): Related Theory for Exercise 2.4.60, , Copyright Free under CC BY Licence

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Fly levelling & check levelling, Objectives: At the end of this lesson you shall be able to, • explain fly levelling, • explain check levelling, • explain indirect levelling., Fly Leveling (Fig 1), , Indirect Levelling, , When different levelling is done in order to connect a, bench mark to the starting point of the alignment of any, project, it is called fly levelling. Fly levelling is also done, to connect the BM to any intermediate point of the, alignment for checking the accuracy of the work., , The method of levelling in which the relative elevations, of the point are found out by some indirect observation, is known as indirect levelling. It may be carried out in, this following three forms., a Barometric levelling, b Hypsometry, c Trigonometrical levelling., Barometric levelling, , In such levelling, only the back sight and fore-sight, readings are taken at every set up of the level and no, distances are measured along the direction of levelling., The level should be set up just midway between the BS, and the FS., Check Levelling (Fig 2), , The indirect levelling which is conducted to fix the relative, elevations of points by the measurement of pressure at, these points using barometer is known as barometric, levelling., Barometric levelling is based on the principle that the, atmospheric pressure varies inversely with the height., This method gives approximate result and so it is adopted, in the reconnaissance or the preliminary survey., Hypsometry, The method of indirect levelling adopted to find the, relatives elevations of points by the measurement boiling, points at these points using hypsometer is known as, hypsometry. It works based on the principle that boiling, points of water decreased at higher altitudes., Trigonometric levelling, , The fly levelling done at the end of day’s work to connect, the finishing point with the starting point on that particular, day is known as check levelling . It is undertaken in order, to check the accuracy of the day’s work., , The method of indirect levelling in which the relative, elevations of different points are obtained by measuring, the vertical angles and horizontal distance is known as, trigonometric levelling., , Problem on reduced levels, Objective: At the end of this lesson you shall be able to, • compute the reduced levels of points and gradiants of lines on sloping ground., Problem in differential levels, Example, , The instrument was shifted after the fourth readings and, the first reading was taken on BM with RL = 100.00 rule, out a page of level book and work out the RL of all points, by collimation method and rise and fall method., , Following consecutive readings were taken on point 1 to, 7 along a line, 0.785, 1.326, 2.538, 3.435, 1.367,2.328, 1.234, 1.657, , Construction: Draughtsman Civil - (NSQF Level -5): Related Theory for Exercise 2.4.60, , Copyright Free under CC BY Licence, , 85

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Station, , Readings, B.S., , 1, , I.S., , Height of line of collimation, , RL, , 100.785, , 100.00, , BM, RL = 100, , F.S, , 0.785, , 2, , 1.326, , 99.459, , 3, , 2.538, , 98.247, , 4, , 1.367, , 3.435, , 98.717, , 97.350, , 5, , 1.238, , 96.389, , 6, , 1.234, , 97.483, , 7, , 1.657, , Total, , 2.152, , Remark, , 97.060, , 5.092, , Solution, , Arithmetical Check, , H.I = R.L. + B.S., , = 100.00 + 0.785, , ∑ B.S. - ∑ F.S., , = 100.785, R.L = H.I – I.S / F.S, , = 02.152 – 5.092, = - 2.940, , = 100.785 – 1.367, , Last R.L – First R.L, , = 99.459, , = 97.060 – 100.00, = 2.940 Ans., , Solution for the above problem is rise and fall method, , Station, , Readings, B.S., , 1, , I.S., , Rise, , RL, , 100.00, , BM, RL = 100, , 2, , 1.326, , 0.541, , 99.459, , 3, , 2.538, , 1.212, , 98.247, , 0.897, , 97.350, , 0.961, , 96.389, , 1.367, , 3.435, , 5, , 2.328, , 6, , 1.234, , 7, , 1.094, 1.657, , ΣB, , 2.152, , Σ F.S, , 5.092, , = 2.152 – 5.092, = - 2.940, , ∑ Rise - ∑ Fall, , = 1.094 – 4.034, = - 2.940, , Last R.L – First R.L, , 97.483, 0.423, , 1.094, , CP, , 97.060, , 4.034, , Exercise 1, , Arithmetical Checks, ∑ B.S. - ∑F.S, , Remark, , F.S, , 0.785, , 4, , Following staff readings were taken with a level. The, instrument having been shifted after the fourth, seventh, and tenth readings. R.L of the starting BM is 150.00m., Enter the readings in the level book page and reduce, the level by the collimation method and apply the usual, checks., , = 97.060 -100.00, = 2.940 Ans., , 86, , Fall, , 1.420, 0.650,3.740, 3.830,0.380, 2.270, 4.640, 0.960,, 1.640, 2,840, 4.680 and 4.980., , Construction: Draughtsman Civil - (NSQF Level -5): Related Theory for Exercise 2.4.60, , Copyright Free under CC BY Licence

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Reciprocal levelling, Objectives: At the end of this lesson you shall be able to, • state the necessity of reciprocal levelling, • explain the procedure of conducting reciprocal levelling., Computation, , Reciprocal Levelling (Fig 1), , Let h = true difference of level between P & Q, E, , = Combined error due to curvature refraction, and imperfect adjustment of line of, collimation., , First Position, The correct readings on staff Q =, , q1 – e, , The correct reading on staff P =, , p1, , Assuming P to be higher than Q, true difference of, level, h, , =, , (q1-e) –p1, , (or), h, , =, , (q1 – p1) - e → 1, , Second position of level, The correct reading on Staff Q =, , q2, , The correct reading on staff P =, , (p2 – e), , The true difference in level, H, , =, , q2 – (p2 – e), , =, , (q2 –p2) + e→2, , h, , =, , (q1 –p1)- e → 1, , h, , =, , (q2-p2) + e → 2, , Procedure, , h+H, , =, , (q1 – p1) – e +, (q2 –p2) + e, , Set up the level very near to P, , 2h, , =, , (q1 – p1) +, (q2 – p2), , When It is not possible to set up the level midway, between two points, as in the case of levelling across a, river or lake, the reciprocal levelling is used., Let P and Q be two points on opposite banks of a lake., , (or), h, Adding equation 1 and 2, , The difference of level between two points P and Q is, found by this method., , With bubble tube central, take staff readings on staff held, at P & Q., i.e, Let the staff readings on P be P1 and Q be q, reading on, P is usually taken through objective. Since the staff is, very close, to get the readings clear, a pencil point is, moved up and down., Transfer the instrument to Q and set it up very near to q., With the bubble central, read the staff held at P& Q., Let the staff readings at P and Q be p 2 and q, respectively., , (i.e) The apparent difference of a level between p and q, is equal to the mean of the apparent differences of level., The combined error can be obtained by equating the, equation 1 and 2, (q1 – p1) – e + (q2 –p2) + e, , 2, , 2e= (q1 – p1) + (q2 – p2), , Construction: Draughtsman Civil - (NSQF Level -5): Related Theory for Exercise 2.4.60, , Copyright Free under CC BY Licence, , 87

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Example 2, , (i.e) combined error is equal to the half of the apparent, difference of the level., , The following notes refer to the reciprocal levels taken, within level., Instrument, , Reciprocal levelling, , station, , Staff readings on, A, , Remarks, , B, , Example 1, In levelling between two points A and B on opposite banks, of a river, the level was setup near A and the staff readings, on A and B were 2.150 and 3.560 respectively. The level, was then moved and setup near B, and the respective, staff readings on A and B were 1.960 and 3.260. Find, the true differences of level of A and B., , 1.630, , Distance and, B = 800 m, , B, , 1.540, , R.L. of A, = 220.540, , 0.940, , Find, i, , Solution, , A between A 1.025, , The true R.L. of B, , ii Combined correction for curvature and refraction., a When the level was setup near A,, Incorrect difference of level = 3.560 – 2.150, = 1.410, , iii The error in collimation adjustment of the instrument., i, , When instrument at A, In correct difference of level between A and B, , b When the level was setup near B,, , = 1.630 - 1.025, , Incorrect difference of level = 3.260 – 1.960, = 1.300, True difference of level of A and B, = mean of the two incorrect differences of, level, , = 0.605, When Instrument at B, Incorrecct difference of level between A and B, = 1.540 – 0.940, = 0.600m, , Fall from A to B, , 88, , Construction: Draughtsman Civil - (NSQF Level -5): Related Theory for Exercise 2.4.60, , Copyright Free under CC BY Licence

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True difference of level between A and B, , = 1.670 – 1.630, , = mean of the two in correct difference, , = 0.040 m, Exercise 1, , (fall from A to B), R.L. at A, , = 220.540 m, , R.L. at B, , = 220.54 – 0.6025m, (Subtract fall), = 219.938 m, , ii Combined correction for curvature and refraction,, = 0.0673D2, , A dumpy level was setup with its eye piece vertically over, a peg C. The height from the top of C to the centre of its, eye piece was measured and found to be 1.570m. The, reading on the staff held on the peg D was 1.005, the, level was then moved and setup at the peg D. The height, of the eye piece above D was 1.250 and the reading on, the staff held on the peg C was 1.810. Determine the, true reduced level of peg D, if that of peg C was 160.000, Exercise 2, , = 0.0673 x (800 / 1000)2, = 0.043 m, iii Instrument at A, , The following details refer to reciprocal levels taken with, a dumpy level., Determine, , Reading at A, , = 1.025, , Fall from A to B, , = 0.602, , The required reading touching the level line, = 1.025 + 0.602, = 1.627, (Showing correct readings when the instrument is at A), , a True difference of level between A and B, b The R.L. of A, , c The error in collimation adjustment of the level., Instrument, station, , Staff readings on, A, , B, , Remarks, , The combined effect of curvature and, refraction is to increase the staff readings., , A, , 1.405, , 2.775, , D i s t a n c e, between A and, B = 1500 m, , Therefore, the observed staff readings at B, touching, the horizontal line should be:, , B, , 0.600, , 1.705, , R.L. of B, = 100.000m, , = 1.627 + 0.043 (combined effect of curvature, and refraction), = 1.670, But the actual observed reading at B. The reading, touching the line of collimation = 1.630 which is less than, 1.670 the line of collimation is inclined downward and, the error due to this, , Longitudinal sectioning and cross sectioning, Objectives: At the end of this lesson you shall be able to, • explain profile levelling and cross sectioning, • explain plotting profile and cross sectioning and working profile, Longitudinal Sectioning (or) Profile levelling, The object of this levelling operation is to obtain a record, of the undulations of the gound surface along the centre, line of a proposed engineering project such as a road,, railway projects, sewage and drainage projects, water, line network projects etc., , The outline of the surface thus obtained is called the, longitudinal section or profile. Therefore, it is also known, as profile levelling. From such a section an engineer is, in a position to study the relationship between the existing, ground surface and the proposed formation of the new, work in the direction of its length., The operation involves observing the elevations of a, number of points along the centre line and also their, , Construction: Draughtsman Civil - (NSQF Level- 5): Related Theory for Exercise 2.4.60, , Copyright Free under CC BY Licence, , 89

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distances along it. The line of section may be a single, straight line running in the centre or may consists of a, series of straight lines according to the change of, direction and connected by curve., , The levels are taken at uniform intervals of distance along, the centre line depending upon the requirements of work, and nature of ground. (A typical profile levelling is shown, in Fig. 1), , Besides these points the staff readings are taken at the, fairly significant point where outlines of the ground, changes appreciably, so that the profile may be obtained, as natural as possible., , The instrument is set up in such a manner as to, command as many points on the section as possible., Staff readings are taken on pages fixed already at desired, regular intervals and also at significant points of change, of slope., , The change point may or may not be on the line of, section., The instrument is then shifted and set up in a new, commanding position and the readings are taken and, entered in the field book., The same procedure is adopted until the end of last point, on the section., , The readings are entered in the appropriate columns of, the levels book against the respective chainages along, the line which are recorded in the distance column., It is necessary to shift the instrument, when the line of, sight is within 100m distance and a change point is, selected on a firm ground or a well-defined object., Checking the Levels, , If the permanent bench mark is available near the end, joint of the section line, the work may be closed on it by, running fly levels from the last station., While entering the readings in the field book with salient, topographic features like river, road, railway, canals, foot, path, drains etc. recorded in remarks column., , At the end of day’s work, the accuracy of work should be, checked by taking fly levels either from permanent bench, mark to another permanent bench mark if available (or), returning back to the permanent bench mark at which, the work started., , Running the longitudinal section, , The closing error = (Σ B.S. - Σ F.S) - (Last R.L - First, R.L.) is calculated., , The line of section is set up on the ground and marked, with pegs driven at equal intervals (varies 10m – 30m), before starting the levelling operation., , If the closing error exceeds the permissible limit, the work, must be repeated., , The levelling operations always commence at a bench, mark and end on a bench mark., If the permanent bench mark is not available near the, line of section, a flying level is to run from any permanent, bench mark to establish a bench mark near the line of, section., 90, , Plotting the ‘L’ Section, In plotting the longitudinal section, a horizontal line drawn, as datum line and chainages of the staff points are, marked along this line to a convenient scale and in black, colour., , Construction: Draughtsman Civil - (NSQF Level -5): Related Theory for Exercise 2.4.60, , Copyright Free under CC BY Licence

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At the plotted points, perpendiculars are erected and on, each lines, the respective levels are set off usually in, black, and the perpendiculars are in thin blue lines., The plotted points are then joined by straight lines to, obtain the outlines of the ground surface are in black, ink., (Usually horizontal scale be 1 cm = 10 m or 1 cm =, 20 m, depends on the vertical scale chosen), The vertical scale for showing the reduced levels is, enlarged to ten times the horizontal scale (i.e) = 1 cm =, 1 m or 2 m, The plotting of maximum level above datum is usually, limited for an engineer at site., , Cross- sections are run at right angles to the longitudinal, sectioning and on either side of it for the purpose of lateral, outline of the ground surface. They provide the data for, estimating quantities of earth work and other purposes., The cross-sections are numbered consecutively from the, beginning of the centre line and are set out right angles, to the centre line of the section with use of cross staff., The distances are measured left and right from the centre, line. Cross-sections are taken at each of these points., The length of cross-section depends upon the nature of, work., The longitudinal and cross sections are worked together, and the observations are recorded in the field work, showing left and right of the centre line as given in the, model tabulation below., , Working profile, Plotting the Cross Section, It is used for the purpose of executing the construction, works for an engineers at site., It shows the features of original ground surface, formation, levels of new work, the proposed gradient. The depths, of cutting and heights of filling and any other information, which may be used for the construction work. The new, work and the formation levels are represented by thick, red line. The original ground (i.e) natural surface levels, are written in black., , Cross sections are plotted in the same manner as the, longitudinal section except that in this case both the, scales are kept equal (i.e) horizontal 1 cm = 1 metre and, vertical 1 cm = 1 metre. (Fig 3), , The gradients of new work are shown prominently and, the limits of each clearly shown by arrows., The depths of cutting are written in red., The heights of filling are written in blue., Cross-Sectioning (Fig 2), , The points to left the centre point are plotted to the left, and those to the right are plotted to the right.The points, obtained are joined by a straight line., , Construction: Draughtsman Civil - (NSQF Level -5): Related Theory for Exercise 2.4.60, , Copyright Free under CC BY Licence, , 91

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Station Distance (m), L, , C, , B.S, , I.S, , F.S, , R.L, , 1.325, 0, , 101.325, , 100.000, , 1.865, , 99.460, , L1, , 3, , 1.905, , 99.420, , L2, , 6, , 2.120, , 99.205, , L3, , 9, , 2.825, , 98.500, , R1, , 3, , 1.705, , 99.620, , R2, , 7.5, , 1.520, , 99.805, , R3, , 10, , 1.955, , 99.370, , 1.265, , 100.060, , I, , 20, , L1, , 3, , 1.365, , 99.960, , L2, , 6, , 0.725, , 100.600, , L3, , 9, , 2.125, , 99.200, , R1, , 3, , 1.925, , 99.400, , R2, , 7, , 2.250, , 99.075, , R3, , 10, , 0.890, , 100.435, , 2.120, , 99.205, , 2.120, , 100.00, , 1.325, , 99.205, , T.P, Check, , 1.325, , Fall, , 92, , Remarks, , R, , BM, O, , H.I, , 0.795, , Fall, , Cross-section at 0 m chainage, , Cross - section at 20m chainage, , 0.795, , Construction: Draughtsman Civil - (NSQF Level -5 ): Related Theory for Exercise 2.4.60, , Copyright Free under CC BY Licence

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Errors in levelling, Objectives: At the end of this lesson you shall be able to, • list the errors occured during levelling operation, • state permissible errors in levelling., Errors in Levelling, , – Recording the readings with digits interchanged, (i.e) 3.275 instead of 3.572, , a Instrumental, , – Omitting an entry, – Error due to imperfect adjustment., – Error due to defective bubble tube., – Error due to sliding movement of objective lens, – Levelling staff of incorrect graduation., – Defective joint of Telescopic staff., – Loose joint of the tripod., , – Entering the inverted staff reading without a minus, sign., – Instead of adding the B.S to B.M of a point,, subtracting the same to get the H.I, – Instead of subtracting the F.S. from H.I of a point,, adding the same to get RL., – Ordinary arithmetical mistakes., Permissible limits of error in levelling, , b National, , – Error due to curvature of Earth, – Error due to refraction, – Error due to variation in Tempeature, – Wind Vibrations., , The degree of accuracy depends upon the following:, – Type of instrument used, – Skill of the observer., – Character of the country., – Atmospheric conditions., , c Personal, , – Length of sight., , Errors in manipulation, , – Number of setups of instrument, , – Imperfect focusing of eye piece and object glass., , The levelling work starts with a B.M. and ends with the, same B.M of the R.L. is same there will be no error., Otherwise there is an error exists., , – Non verticality of staff., , The permissible closing error is expressed as,, , – Careless in setting up of level, , – The bubble not being central at the time of taking, readings, , E=C x, , Errors in reading staff, , K in metric units, , E = permissible closing error in mm, , – Reading the staff upwards instead of downwards., , C = constant varies according to the type of survey, , – Reading the inverted staff as in normal vertically, , K = distance in km, , held staff., , – Reading wrong metre mark, when the staff is very, near to the level., , Rough levelling E ± 0.100, Ordinary Levelling : E ± 0.025, , – Reading against the top or bottom hair instead of, Accurate levelling : E ± 0.012, , central hair, Errors in recording and computation, , Precise levelling: E ± 0.006, , – Entering a reading in the wrong column, , Construction: Draughtsman Civil - (NSQF Level -5 ): Related Theory for Exercise 2.4.60, , Copyright Free under CC BY Licence, , 93

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Construction, Related Theory for Exercise 2.4.61, Draughtsman Civil - Levelling and contouring, Introducing to contouring, Objectives : At the end of this lesson you shall be able to, • define contouring, • explain the terms used in contouring, • narrate the characteristics of contour., Introduction, , Scale of the Map, , Relief, , The contour intervals kept inversely proportional to the, scale of the map. Smaller the scale of map, larger the, contour interval. On the other hand, if the scale of the, map is large, the contour interval should be small., , The topographical map showing the configuration of the, earth’s surface by the use of suitable symbols is called, relief. Contour lines are used for representing relief., , Purpose of Map & Extent of Survey, Contour Line, A contour line is an imaginary line of constant elevation, on the ground surface. It may be the line of intersection, of level surface with good surface., E.g show line of still pond or a lake., Contouring, The process of locating the contour lines on the surface, of the earth or on the plan or map is known as contouring., , For small extent of survey and for detailed design work, contour interval should be small. For large extent of, survey, the contour interval shall be large. For the survey, of canal, railway, road etc. If the work is very important,, contour interval should be less and vice versa., Nature of the ground, The contour interval generally depends upon the, topography of the terrain. In flat ground contour interval, is small so that it will be suitable to depict the general, nature of the ground. Whereas in hilly areas can be, depicted with contours at larger interval., , Contour interval, Availability of time and fund, The vertical distance between two consecutive contours, is called contour interval. It is kept constant for a contour, plan to correctly represent the topography of the terrain., Horizontal equivalent, The least horizontal distance between two consecutive, contours is called horizontal equivalent. It is different at, different part of the contours and it depends upon the, slope of the ground. It is usually less in hills than in plains., , If the time and fund available is less, large contour interval, is adopted or vice versa. This is due to the fact that the, greater the interval, the smaller is the amount of field, work, reduction and plotting required in the preparation, of the plan., The contour interval for general topographical may be, computed by the following rule., , Factors for deciding contour interval, Contour interval on a map is decided on the following, considerations., Considering the above factors, the contour intervals, recommended for the contour plans for various purposes, are as follows., , 94, , Copyright Free under CC BY Licence

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S No., , Purpose of Survey, , Scale, , Contour Interval in Metre, , 1, , Building site, , 1c m = 10 m or less, , 0.2 to 0.5, , 2, , Town planning schemes,, reservoirs landscape grading, , 1 cm = 50 m to 100 m, , 0.5 to 2, , 3, , Location surveying, , 1 cm = 50 cm to 200 m, , 2 to 3, , 4, , For general topographical, work, , 1 cm = 100 m or more, , 3 m & above, , Uses of contours, Objectives: At the end of this lesson you shall be able to, • explain the uses of contour, • explain the methods of contouring, Uses of contour maps, , Methods of Contouring, , •, , To study the general character of a tract of land without, visiting the ground if the countour map of the area is, available., , The method of locating contours may be classified into, two Direct method and indirect method., , •, , To decide the most economical and suitable site for, engineering works such as canals, sewers, reservoirs,, roads, railway etc., , •, , To determine the capacity of the reservoirs and the, catchment area of a drainage basins., , •, , To compute quantity of earth work required for filling, or cutting along the proposed alignment of the project, such as canals, roads etc., , •, , To ascertain the invisibility of points., , •, , To trace gradient for the road alignment., , •, , To draw longitudinal section and cross section to, ascertain the nature of the ground in any desired, direction., , •, , To decide the best positions for the guns, the line of, march and campaining grounds by the army, commanders during wars., , Locating Contours, The location of contour on a map can be plotted only, after knowing the horizontal position and vertical elevation, of the points consisting of the contours. The fixing of the, horizontal position of the points is known as horizontal, control and it depends upon the size, shape and, importance of work. It may be carried out either by chain, survey or compass survey or plane table survey. For, small areas, chain survey is adopted and for large areas, traversing is adopted., The fixing of the vertical height of points is known as, vertical control and it is carried out by the process of, levelling., , Direct Method, In this method, the contours to be located are directly, traced out in the field with a level or hand level by marking, various points along a contour. These points are then, surveyed and whose positions are plotted. The line joining, these points gives the required contour., This method is very slow and tedious , but it gives very, accurate results. It is used for small areas and for works, of high precision., In this method, first a temporary BM is established in the, area where contouring is to be done by running fly levels, from a permanent BM. Then the level is set up at a, position from where maximum area can be visible. For a, BS reading is taken on the BM. From that calculate the, height of instrument. To locate the points along a, particular contour, required staff reading is calculated by, subtracting the reduced level from the height of, instrument., Then contour points are located by moving the staff up, and down along the slope until the desired staff reading, is obtained. The points are surveyed and whose positions, are plotted on the plan., Direct method by radial line, In this method, contour points are located along the radial, lines from a common point at the centre., Select a point at the centre of the area to be surveyed so, that all the points can be commanded from that point, and their relative positions are fixed by measuring the, , Construction: Draughtsman Civil - (NSQF Level -5): Related Theory for Exercise 2.4.61, , Copyright Free under CC BY Licence, , 95

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horizontal angles or bearing. Place the levelling, instrument over the selected point and find the height of, instrument with reference to the temporary BM, established on the contour site. Calculate the staff, readings required, to locate the points along various, contours of different reduced levels., , 96, , Hold the staff vertically and move up and down along, these radial lines until desired staff readings for their, respective contours are obtained. The positions of these, points obtained are located by measuring their distances, from centre point. Join the points of same elevations to, get the required contours., , Construction: Draughtsman Civil - (NSQF Level -5): Related Theory for Exercise 2.4.61, , Copyright Free under CC BY Licence

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Construction, Related Theory for Exercise 2.4.62 - 2.4.65, Draughtsman Civil - Levelling and contouring, Interpolation of contours, Objectives: At the end of this lesson you shall be able to, • explain the term interpolation, • explain the various methods of interpolation of contours., Interpolation of Contours, The process of placing or spacing the contour lines, proportionally between the plotted ground points is known, an interpolation of contours. It is based on the, assumption that the slope of ground between two points, is uniform., Contours may be interpolated by the following methods., 1 By estimation, 2 By arithmetical calculation, 3 By graphical method., 1 By estimation, In this method the position of contour point is judged by, estimation. The method is rapid. But it gives approximate, results. It is used for small scale map., , Hence the point of reduced levels 42 m and 43m are, 2.8m and 6.8 m distance away from A. The contour, points are then plotted, by scaling these distances to the, scale of the map., 3 By Graphical Method, Graphical methods of interpolation are simpler as, compared to arithmetical methods and also the results, obtained are accurate. Out of several graphical methods,, the one in common use is explained below., Suppose the contour interval is 5 m, then on a piece of, tracing cloth, a number of parallel lines spaced at 0.5m, (usually one tenth of the contour interval) are drawn,, every tenth line being made thick (Fig 1). Suppose it is, required to interpolate contours between two points A, and B of elevations 61.5 and 72.5m respectively., , 2 By Arthimetical calculation, In this method of interpolation, the portion of contour, points in between the plotted ground points are located, by calculating their distance accurately based on their, ratios of distance and level difference. This method is, laborious and tedious. But it is the most accurate method., E.g., let A and B are two points at a distance of 10 m and, have reduced levels 41.3 and 43.6m respectively., Assuming 1 m contour interval, contours of 42 m and, 43 m may be plotted between A and B., Difference in level between A and B, = 43.8 – 41.3 = 2.5 m, Distance between A and B, , =, , 10 m, , Difference in level between A and B 42 m contour, =, , 42 – 41.3 = 0.7m, , If the bottom line represents an elevation of 60m, then, the successive thick lines will represent 65m, 70m and, 75 m etc. Place the tracing cloth so that the point A is on, the third line from the bottom. Now, move the tracing, cloth until B is on the fifth line above the 70 m thick line., The intersections of the thick lines 1 and 2 representing, elevations of 65 m and 70 m contours respectively and, picked through on the plan with a pin., , Difference level between A and B 43m contour, = 43 - 41.3 = 1.7m, Distance of A and 42m contour, =, Distance of A and 43m contour, =, , 10 x 0.7 /2.5 = 2.8m, , Drawing of contour, After establishing points on the various contours, contour, lines are drawn as fine and smooth free hand curved, lines of uniform thickness. They may also be represented, by broken lines. The line should be linked either in black, or brown. Red or crimson lake may be also used for, inking in special cases. Curves may be drawn with, French curves as far as possible., , 97, , Copyright Free under CC BY Licence

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Usually every fifth contour is thicker than the rest., Elevations are in the uniform manner. The figures, indicating the elevation of contour are written at the, begining, middle and at the end of the contour lines. The, figures should be normal to the contours and they should, be placed uniformly in such way, that they can be read, from one or two ends on the contour map., , Contour gradient, Objectives: At the end of this lesson you shall be able to, • describe the term contour gradient, • explain the method of locating contour gradient, • explain the method of erecting grade stake., Contour Gradient, , Setting Grade stake, , Contour gradient may be defined as a line lying on the, surface of the ground with uniform inclination to the, horizontal at all points on it., , It is the process of erecting the stakes at a given elevation, or gradient. They indicate cut or fill required to bring the, surface of the ground to a given grade. Knowing the, formation level at each chainage from the profile and, height of instrument calculate the staff reading required, to set a given grade. Staff reading may be calculated by, subtracting the formation level from the height of, instrument. This staff reading is called grade rod., , Locating a Contour Gradient on a Contour Plan:, While locating a highway or railway or canal contour map, a controlling factor is the gradient line. In portions of the, location, the grade line ascends or descends at a uniform, rate. At some places the grade line may be at the, maximum gradient permissible. A uniform grade line can, be drawn on the map by first calculating the horizontal, distance corresponding to the contour interval and the, given gradient., Let A be the point on a contour line of RL 60.00m from, which it is required to trace the contour gradient with, ruling gradient of 1 in 30 (falling)., In the contour plan contour lines are drawn with a contour, interval of 2 m. Since the contour intervals is 2 m and, the gradient is 1 in 30, the horizontal distance required, between successive points on consecutive contours is, 60 m (30 x 2m). With A as centre and the horizontal, distance 60 m to the scale of the drawing as radius, draw, an arc cutting 58 m contour at B and B1., Considering the point lying nearer to the progressive, direction of the centre route, the point is selected. Let it, be B. Then B as centre and with the same radius draw, another arc cutting the 56 m contour at C. Select the, suitable point and repeat the same process upto the last, contour. The line joining the points, A, B, C,D etc. gives, the alignment for the given gradient., The contour gradient thus established on the contour, map can be then transferred to the field by the use of, suitable surveying instrument., Grade Stakes, Stakes or pegs erected in ground in such a way that, their top is at the formation level or their top at any whole, number of metres above or below the formation level., 98, , Stake may be set out in several methods, one of, which is explained below, Each stakes may be driven so that its top is any whole, numbes of metres above or below grade for formation, level., Suppose the formation level of the point 130.000m and, the ground level at that point is 132.265m. The height of, instrument has been found to be 134.255, The grade rod or staff reading required, = HI – formation level., = 134.255 – 130.000, = 4.255m, The surface of ground is raised, = GL – formation level., = 132.265 – 130.000, = 2.265 m above ground., As the ground is above the formation level we cannot, erect the pegs at formation level A. So it may be erected, at some whole numbers of metres above formation. Let, the stake may be erected 2.5 m above the formation, level., The staff reading required to establish the stake 2.5m, above grade or formation level., , Construction: Draughtsman Civil - (NSQF Level -5): Related Theory for Exercise 2.4.62 - 65, , Copyright Free under CC BY Licence

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= Grade rod – formation, vertical distance, = 4.255 – 2.5000, = 1.755 m, The stake is driven into the point A until its top staff, reading obtained is 1.755 m. The stake is then marked, out 2.5000 with crayon., , Uses of contours and direct method, Objectives: At the end of this lesson you shall be able to, • explain the uses of contour, • explain the methods of contouring, Uses of Contour maps, •, , To study the general character of a tract of land without, visiting the ground if the contour map of the area is, available., , •, , To decide the most economical and suitable site for, engineering works such as canals, sewers, reservoirs,, roads, railways etc., , •, , To determine the capacity of the reservoirs and the, catchment area of drainage basins., , •, , To compute quantity of earth work required for filling, or cutting along the proposed alignment of the project, such as canals, road etc., , • To ascertain the indivisibility of points., • To trace gradient for the road alignment., • To draw longitudinal section and cross section to, ascertain the nature of the ground in any desired, direction., •, , To decide the best positions for the guns, the line of, march and campaining grounds by the army, commanders during wars., , Method of Contouring, The method of locating contours may be classified into, two. Direct method and indirect method., Direct Method, In this method, the contours to be located are directly, traced out in the field with a level or hand level by marking, various points along a contour. These points are then, surveyed and whose positions are plotted. The line, joining these points gives the required contour., The method is very slow and tedious, but it gives very, accurate results. It is used for small areas and for works, of high precision., In this method, first a temporary BM is established in the, area where contouring is to be done by running fly levels, from a permanent BM. Then the level is set up at a, position form where maximum area can be visible. For A, BS reading is taken on the BM, From that calculate the, height of instrument. To locate the points along a, particular contour, required staff reading is calculated by, subtracting the reduced level from the height of, instrument., , Locating Contours, The location of contour on a map can be plotted only, after knowing the horizontal position and vertical elevation, of the point consisting of the contours. The fixing of the, horizontal position of points is known as horizontal control, and it depends upon the size, shape and importance of, work. I t may be carried out either by chain surveying or, compass survey or plane table survey. For small areas,, chain survey is adopted and for large areas traversing is, adopted., The fixing of the vertical height of points is known as, vertical control and it is carried out by the process of, levelling., , Then contour points are located by moving the staff up, and down along the slope until the desired staff reading, is obtained. The points are surveyed and whose positions, are plotted on the plan., Direct method by radial line, In this method, contour points are located along the radial, lines from a common point at the centre., Select a point at the centre of the area to be surveyed so, that all the points can be commanded from that point, and their relative positions are fixed by measuring the, horizontal angles or bearings. Place the levelling, instrument over the selected point and find the height of, instrument with reference to the temporary BM, established on the contour site. Calculate the staff, , Construction: Draughtsman Civil - (NSQF Level -5): Related Theory for Exercise 2.4.62 - 65, , Copyright Free under CC BY Licence, , 99

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readings required, to locate the points along various, contours of different reduced levels., Hold the staff vertically and move up and down along, these radial lines until desired staff readings for their, , respective contours are obtained. The positions of these, points obtained are located by measuring their distances, from centre point. Join the points of same elevations to, get the required contours., , Road projects, Objectives: At the end of this lesson you shall be able to, • describe the necessity of road projects, • explain various types of surveys involved in road project., Introduction, , The reconnaissance survey may be conducted in the, following sequence., , Before construction a new road due to public demand or, some strategic reason, a primary investigation is carred, out to examine whether this road is necessary., , •, , Study of topographical survey sheets, agricultural soil,, geological and meterological maps and aerial, photographs if available., , The following points are to be kept in mind at the time of, such investigation., , •, , Aerial reconnaissance, , •, , Ground reconnaissance, , Total population benefitted by the project., Study of topographical survey sheet, Number of villages, towns, industrial places etc to be, connected., Prospect of tourism, if any., Strategic importance for the defence of the country., Any other information related to the project should be, noted., , Reconnaissance begins with the study of all available, maps. In india topographical sheets are available to the, scale of 1:50,000. After the study of the topographical, features on the maps, a number of alignment feasible in, a general way are selected while selecting the alignment, following points should be kept in view., •, , The alignment should be shortest and most, economical with the requirements of gradient and, curvature., , •, , Shape of the alignment, , •, , As far as possible avoid marshy ground, steep terrain,, unstable hill features., , •, , Need of connecting important villages and towns,, industrial places, places of religious importance etc., , •, , Number of bridges and their lengths., , Types of Surveys for the location of a road, Before finalising the alignment of a road, the engineering, surveys must be carried out in four following stages., •, , Map study, , •, , Reconnaissance survey, , •, , Preliminary survey, , •, , Final survey, , Map Study, In this map study if the topographic map of the area is, available, the selected routes of the road may be marked, on it. The alignment can be located on the map from the, following available details., •, , Avoidable points, such as ponds, valleys, lakes etc., , •, , Possibly of crossing through a mountain pass., , •, , Location of a bridge site for crossing the river, avoiding, bends etc., , If the photographs of the area are not available, aerial, photography may be arranged for further study for the, sake of overall economy. These photographs may be, taken on a scale of 1:20,000 to 1:50,000., Aerial reconnaissance, Final alignment is selected on the basis of the aerial, reconnaissance. It will also help to identify factors which, may be helpful with the rejection or modification of any, of the alignment. This will provide a bird’s eye view of, the alignments under consideration along with the, surrounding area., , Reconnaissance survey, , Ground reconnaissance, , The main object of this survey is to examine the general, characteristics of the area for determining the most, feasible route or routes for further detailed investigations., , It consists of general examination of the ground by, walking or riding along the selected alignment of a road., It may be done by using the following instruments., , 100, , Construction: Draughtsman Civil - (NSQF Level -5): Related Theory for Exercise 2.4.62 - 65, , Copyright Free under CC BY Licence

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•, , Compass, , •, , Abney level, , •, , Pedometer, , •, , Clino meter, , •, , Ghat tracer, , Preliminary survey, , During this survey following points should be kept in mind., •, , Details of route, , •, , Length of the road, , •, , Number of bridges and their lengths, , •, , Geometrics / Gradients, curves and hair pin bends, etc., , •, , Right of way available., , Terrain and soil conditions, , This survey is relatively large scale instrument survey, conducted for the purpose of collecting all physical, information which affects the proposed location of a new, highway. In case of new road it consists of running an, accurate traverse line along the new route selected, on, the basis of reconnaissance survey. During this phase, of survey, topographic features and other features like, houses, places of worships etc. Are to be considered., Longitudinal sections and cross sections are taken and, bench marks established. This data will form the basis, for the determination of final centre line of the road., During preliminary survey usually levelling work should, be kept to the minimum. Generally fly levels at 50 m, intervals and at all intermediate breaks in ground should, be taken along the traverse line., The cross section at about 100m to 250 m, intervals in plain terrain and at about 50 m, intervals in rolling terrain should be taken., , Geology of area, nature of soil, drainage conditions and, nature of hill slopes., Road length passing through, , Final Location Survey, , •, , Mountainous terrain., , •, , Steep terrain, , •, , Area subjected to inundation and flooding., , • Area of poor soil and drainage conditions, , This survey is carried out to lay out the final centre line, of the road in the field based on the alignment selected, in the design office and to collect the necessary data for, the preparation of working drawings. In this survey only, two step are involved., , • General elevation of the road., , •, , Staking out the final centre line of the road by means, of a continuous transit survey., , •, , Detailed levelling., , Climatic Conditions, •, , Temperature – maximum and minimum readings, , •, , Rainfall, , •, , Wind velocities and direction, , •, , Water table conditions., , Road Alignment, , Value of Land, Agricultural land, irrigation land, built up land, forest land, etc., •, , Approximate cost of construction, , •, , Period required for construction, , •, , Important villages, towns and marketing centres, connected., , •, , Crossings with railway lines and other existing, highways., , •, , Position of ancient monuments, burial grounds,, religious structures, hospitals and schools etc., , The position or the layout of the centre line of the highway, on the ground is called the alignment. In a new road, should be aligned carefully otherwise it is faulty. It causes, more construction, maintenance cost and also increase, the accident rates., The alignment may be,, •, , Short, , •, , It should be easy, , •, , It should be safe, , •, , It should be economical, , •, , Height of embankment., , The height of the embankment depends upon the desired, grade line of the highway and topography of the area., Sometimes, it is also governed by the stability of, foundation specially when the soil is weak usually it is, taken 0.6m., , Construction: Draughtsman Civil - (NSQF Level -5): Related Theory for Exercise 2.4.62 - 65, , Copyright Free under CC BY Licence, , 101

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Road Gradient, , The maximum, ruling and exceptional gradients as, , The rate of rise or fall along the length of the road with, respect to the horizontal length is called gradient., Sl No, , Type of Terrain, , Maximum, gradient, , 1, , Plain or rolling, , 1 in 20, , 2, , Mountainous and, , 1 in 16.7, , steep terrain with, , recommended by Indian Road Congress are given below:, Road Way, Road way comprises of the width of carriageway including, traffic separator and shoulder on either side., Road way width as per recommendations of I.R.C, National and State Highway, , 12.0m, , Major District Roads, , 10.0m, , Other district roads, , 8.0 m, , Village Roads, , 7.5 m, , elevation upto 3000m, 3, , Elevation more than, 3000m, , 102, , 1 in 14.3, , Construction: Draughtsman Civil - (NSQF Level -5): Related Theory for Exercise 2.4.62 - 65, , Copyright Free under CC BY Licence

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Construction, Related Theory for Exercise 2.4.66 - 2.4.68, Draughtsman Civil - Levelling and contouring, Indirect method of contouring, Objectives : At the end of this lesson you shall be able to, • explain the indirect method by squares, • explain the indirect method by cross section, • explain the indirect methods by tacheometric., This method of contouring is commonly used because it, is simple, quick and chaper. In this method spot levels, are taken along a series of lines laid over the area. The, positions of these points are then plotted on the plan, already prepared by other method of surveying and the, contours of reduced levels are drawn by interpolation., This method is also known as contouring by spot levels., This is done by any one of the following methods., , The spacing of the cross section depends upon the, nature of the ground, contour interval and scale of plan., Usually the interval being 20 m in hilly area and 100m in, flat country. Then, points at the interval of 5m or 10m, are marked along the cross section lines. Points of salient, features along the centre line and cross section line are, also located., , 3 By tacheometry, , The layout of the cross sections need not be at right, angles to the centre line. They may be inclined at suitable, angles to the centre line. The reduced levels of the points, are determined. The contours of required reduced level, are plotted by interpolation., , 1 By squares, , 3 By techeometric method, , This method is suitable for small and low undulating area., In this method the area to be surveyed is divided into a, network of squares by running a series of lines at right, angles. The corners of these squares are marked with, pegs or arrows. Depending upon the nature of ground,, the sides of squares may be uniform or varying. The, reduced levels of the corners of the squares are, determined by levelling the squares are also taken and, are located., , This method is suitable for contouring of hilly areas. An, instrument station is chosen at the peak of area. Set up, the techeometer over that point and a number of radial, lines at known angular interval are drawn on the ground., The interval may vary from 100 to 300 depending upon, the nature of ground., , 1 By squares, 2 By cross section, , The squares are plotted to the desired scale on the plan, and reduced levels of the corners as well as sailent points, are entered. The contours of desired values are then, interpolated., 2 By Cross Section, This method is suitable for long and narrow strips of land, such as road or canal or railway. A centre line is laid, down through the centre of the area to be contoured, Cross sections perpendicular to the centre line are, erected at regular intervals., , Number of representative points are chosen along these, radial lines. These points are located by observing the, vertical angles and the staff readings of the bottom,, middle and top wires. The horizontal distances of these, points from instrument station and reduced levels are, calculated by using the techeometric formulae, The radial lines and the positions of the points on each, line are plotted to the desired scale and their elevations, are also noted. Then the contour lines are drawn by, interpolation., , 103, , Copyright Free under CC BY Licence

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Comparision between direct and indirect method, Direct method, , Indirect method, , It is the most accurate method. But is slow and tedious, , The method is cheaper and rapid and less tedious, but not very accurate., , It is used for small areas, where great accuracy is, the desired, , It is used for large area where great accuracy is not, the main consideration., , It is not suitable in hilly areas, , The tacheometric method of contouring is particularly, used for hilly areas.The indrect method by cross, section is used in route surveys such as road, canal etc., , The calculation work of reducing the level is, comparatively more, since the number of points in, command from one set of the level is very less, , Area commond from one set of the tacheometer is, more, therefore the calculation work is less., , Topography and contour, Objectives: At the end of this lesson you shall be able to, • state topography, • state contour., Topography, In the earth surface the natural features such as rivers, lakes, streams. Woods and hills etc. and artificial objects, such as roads, railways, canals, towns and villages etc., The above features are then surveyed by means of linear, and angular measurements are plotted to a plan or a, map. It is called as a topographic map. For various, purpose of work different scales are used., 1 Building sites, 1cm=10m (or) less, , For vertical measurements some conventional must be, adopted. In one way showing vertical measurements by, means of longitudinal sectioning and cross- sectioning., Contours are more efficient way of showing the, elevations directly on the map. It is the imaginary line, on the ground joining the points of constant elevation. It, is a line in which the surface of the ground intersected, by a level surface., It is the process of tracing contour lines on the surface, of the earth and it is down on a map are called contour, map., For example (Fig.1), , 2 Town planning schemes = 1cm= 50m to 100m, , 3 Location surveys 1 cm = 50cm to 200m, , 4 Small scale topographic maps = 1 cm = 0.25km to, 2.5km, If a pond with water level at an elevation of 55m is shown, in plan (Fig.1) as a water mark., , Contour, In a plan only the horizontal dimensions are down. (i.e.), (The length and width of objects are surveyed and shown), , 104, , If the water level is lowered by one meter, then another, water mark will be obtained and represented as 54.00m., Again the water level is lower by one metre successively,, the successive water mark line repressor 53cm, 52m, etc., will be obtained then the water maks are shown on, the map in the form of contours., , Construction: Draughtsman Civil - (NSQF Level -5): Related Theory for Exercise 2.4.66 - 68, , Copyright Free under CC BY Licence

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Therefore, all the points on anyone contour lasing the, same elevation above datum’s., , While seeing the contour map it will furnishes the, information regarding the ground is flat, steep ground, undulated hill, pond etc. are known., , Map Reading, Objectives: At the end of this lesson you shall be able to, • state map, • state grid refresh., Map, •, , A map is a drawing of a landscape of location., , •, , Map can be seen from the above looking directly, down., , •, , The map showing, the landscape of an area will show, the after features such as road, rivers, buildings, trees, and lakes., , •, , The map is given an idea of a land mark for easy to, journey and how far will be travelled along the route., , This grid system makes simple and accurate description, of your location and this description will be in series of, numbers and it is called as a grid reference., Grid References (Fig 1), , In a map, it will show a smaller places such as street, foot paths, a small building etc., In another type of a map it show a mountain, river valley, etc., For avoiding writing of description the symbols are used, in map. Normally the map should included, road, foot, path, woods, buildings, river and streams, mountains and, valley and scale., The scale may be 1:50000, Survey maps are covered in series of blue lines and it, makes up a grid. These lines have numbers and, accompanying them to allow accurately pin point your, location of map., , All the numbers going across the face of the map, left to, right are called easting’s., All the numbers going up the face of the map from bottom, to top are called northings., , Trignometric levelling (Indirect levelling), Objectives: At the end of this lesson you shall be able to, • state advantage of indirect levelling., • explain various cases of trignometric levelling., • deduce the reduced level using the appropriate formula., This is an indirect method of levelling in which the, difference in elevation of the points is determined from, the observed vertical angles and the measured, distances., , Depending upon the field conditions, different cases may, arrive. Some of the cases are discussed below., , The vertical angles are generally measured by theodolite, and the horizontal distances are either measured or, computed., , Case 2. Base of the objects inaccessible, instrument, stations in the same vertical plane as the elevated object., , Trignometric levelling is commonly used in topographical, works because of it is very advantages in mountainous, terrain., , Case 1. Base of the object accessible., , Case3. Base of the object inaccessible, instrument, stations not in the same vertical plane as the elevated, object., , Construction: Draughtsman Civil - (NSQF Level -5): Related Theory for Exercise 2.4.66 - 68, , Copyright Free under CC BY Licence, , 105

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Case 1 (a) ( Fig 1), , = 100.00 + 0.745 + 7.160, = 107.905m, , Base of the object accessible- the object vertical, Let AB is the vertical object., , Case 1 (b) (Fig 3), , D is the horizontal distance between the object and the, instrument., S is the staff reading on the levelling staff held vertical, on the B.M., h is the height of the object above vertical axis., α is the angle of elevation to the top of the object., From triangle BCD., BC, , = CD x tan α, , h, , = D X tan α, , R.L. of B, , = R.L. of B.M + S + h, = R.L. of B.M + S+D tan α, , Base of the object accessible – the object inclined, , In instrument was set up at point O. With horizontal sight, when staff held at a bench mark of 100.000m, reading, was 0.745m The horizontal distance between a point, A, from O is 19.950m and A was observed at an angle of, elevation 190 44’.45". Determine the RL of A., , In figure AF is the inclined object, x is the distance, between the foot of the object and the projection F’ of, the top O1 and O2 and A are in the same vertical plane,, D1 and D2 are the distances of the foot of the object from, the instrument stations O1 and O2 respectively. S1 and, S2 . Are the staff reading on B.M from instrument positions, at O1 and O2 respective and α1 and α2 are the angles of, elevation from O1 and O2 respectively., , Solution (Fig 2), , R.L of F as per set up of instrument at O1, , Exercise, , α, , = 19° 44’45", , D, , = 19.950 m, , S, , = 0.745m, , h, , = D x tan α, = 19.950 x tan 19° 44’45", = 7.160 m, , R.L. of A, 106, , = R.L. of B.M + S1 + h1, = R.L of B.M + S1 + ( D1 + x), tan α1 - Eq (1), R.L of F as per set up of instrument at O2, = R.L. of B.M + S2 + h2, , = R.L. of BM + S +h, , Construction: Draughtsman Civil - (NSQF Level -5): Related Theory for Exercise 2.4.66 - 68, , Copyright Free under CC BY Licence

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= R.L. of B.M + S2 + (D2 – X), tanα 2 - Eq (2), , From Eq (1) and Eq (2), , From triangle Q1 Q’P,, , = h D tan α1 →, , From triangle Q2 Q'’P,, , h =(D + d) tan α2 → Eq (2), , Eq (1), , Equating both equations, , R.L of F can be calculated after computing the value of, x., R.L of F = R.L of B.M + S1 + (D1 + X) tan α1, R.L of F = R.L of B.M + S2 + (D2 + X) tan α2, , R.L of P = R.L.of B.M + S + h, Heights of Instrument are at different Levels, , Case 2, Base of the object inaccessible – instrument stations, and the elevated object the same vertical Plane, (Single plane method) Fig 4., , There are three cases, Instrument axis at O1 higher than that at O2, Instrument axis at O2 higher than that at O1, Instrument axis at different levels, Instrument axis at O1 higher than that at O2, Fig 5. Single Plane: O1 higher than O2, , If the horizontal distance between the instrument and, the elevated object is in accessible, the observations are, made from two instrument stations. Assuming the two, instrument stations and the object to be in the same, vertical plane there may be two cases., Height of instrument are same,, , h1 - h2 =Q’Q” = S1- S2 = S, , Heights of instrument are at different levels., , From triangle O1 Q’P,h1 = D tan α 1 -, , Heights of instrument are same, , From triangle O2 Q”P, h2 = (D+d) tan α 2 - Eq (2), , h is the vertical distance PQ', , From equations 1 and 2, , Eq (1), , S is the staff reading on the B.M, α1 and α1 are the angles of elevation measured at, instrument station O1 and the object, , D, , d is the horizontal distance between the two stations., therefore, Fig 4. Single plane, ‘H’ Bottom & ‘S’ Top are at same, level, R.L of P, , = R.L of B.M + S1 + h1, , or, , Construction: Draughtsman Civil - (NSQF Level -5): Related Theory for Exercise 2.4.66 - 68, , Copyright Free under CC BY Licence, , 107

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R.L. of P, , = R.L of B.M + S2 + h2, , Instrument axis at O2 higher than that at O1, Fig 6 Single plane method O2 higher than O1, , Therefore S = h2 – h1, h1 - h2 = Q’ Q” = S2 – S1 = s, From triangle O1 Q’P,h1, , = D tan α1 -, , From triangle O2 Q”P, h2, , = (D+d) tan α2 - Eq (2), , Eq (1), , From equations 1 and 2, , Height of station O1 at above the axis at O2, = h–v, , D=, = d tan α 3 - y, S, h1 =, , = d tanα, , Hence R.L. of P, , R.L. of P, , = R.L of B.M. +S1 +h1, , R.L. of P, , = R.L. of B.M. + S2 +h2, , If the difference in elevation (S2- S1) between the two, instrument stations is too large and cannot be measured, on a staff at the B.M then the following procedure is, adopted., Single plane method: Level difference between two, stations is greater, Set up the instrument at O1 and measure the vertical, angle at the point P., Transit the telescope and establish a point O2, , - r+h, , = R.L. of B.M. + S1 + S + h1, = R.L. of B.M + S1 +, d tan α 3 - y +h’+h1, , or, , Instrument axes at different levels, , 3, , Exercise, The following observations were made on chimney top, to ascertain its elevation., Instrument, station, , Staff reading, on BM, , Angle of elevation, , O1, , 1.035, , 20°00’00", , O2, , 0.915, , 13°00’00", , Reduced level of BM was 100.000m. The instrument, stations were 20.00m apart and were in line with the, chimney top A. Find the RL of the A., Solution, , Shift the instrument to O2 and measure the vertical angle, at the point P., , S1, , = 1.035m, α1, , =, , 20°00’00", , Observe the staff reading Y on the staff at O1, , S2, , = 0.915M, α2, , =, , 13°00’00", , Let S be the difference in level between the two axes at, O1 and O2, , RL of BM, , =, , 100°000 M, , 108, , Construction: Draughtsman Civil - (NSQF Level -5): Related Theory for Exercise 2.4.66 - 68, , Copyright Free under CC BY Licence

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d, S, , = 1.035 – 0.915, , =, , 20.00M, , =, , 0.120 m, , From staff reading we know that observations taken from, near to the point A is lower than the other observation., (i.e.) O1 is higher than O2 (single plane method,, instrument axes at different levels., So D, , =, , (d tanα2 S) / (tan α 1 - tan α 2), , =, , (20 x tan 13°00’00" – 0.120) /, (tan 20°00’00") – tan 13°00’00"), , =, , (4.61 -0.120) / (0.3639 – 0.2308), , =, , 33.78m, , Therefore h1 =, , RL of A, , D tan α 1, , =, , 33.78 x tan 20° 0’ 00" = 12.297m, , =, , RL of BM + S1 +h1, , =, , 100.000 + 1.035 + 12.297, , =, , 113.332m, , d is the horizontal distance between the instrument, stations,, α1 and α 2 are the angles the elevation to the point P from, the stations respectively., S1 and S2 are the staff reading on the B.M from the, instrument stations., In triangle O1 O2 Q', O1 O’Q2 = 180° - (α +β) = θ, By the sine rule, , or, RL of A, , =, , RL of BM + S2 + h2, , h2, , =, , (D+d) x tan α2 =(33.78 + 20), tan 13°00’00, , Therefore RL of A =, , 100.000 + 0.915 +(33.78+20), x tan 13°00’00, , Case 3, , h1, h2, , Double plane method (Fig 9), The point P is sighted from two stations, hence point is, contained in two vertical planes so it is called double, plane method. The method is depicted in the picture., Point P is sighted from two instrument stations O1 and, O2, , = Q”O1 tan α,, , =, , Q’P, , =, , A’ O1 tan α1, , =, , Q”P, , =, , Q’ O2 tan α2, , = Q” O2 tan α2, , R.L. of F from O1, , = R.L. of B.M. + S1 + d, (sinα tan α1 / Sin), , R.L. of F O2, , = R.L. of B.M + S2 + d, (sinβ tan α2 / Sin), , Average of these two RLS is the required RL of F., , Construction: Draughtsman Civil - (NSQF Level -5): Related Theory for Exercise 2.4.66 - 68, , Copyright Free under CC BY Licence, , 109

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Construction, Draughtsman Civil - Theodolite, , Related Theory for Exercise 2.5.69, , Introduction to theodolite, Objectives: At the end of this lesson you shall be able to, • explain the uses of theodolite, • explain the classify theodolite, • explain the designate theodolite., , Introduction, Theodolite is primarily used for measuring horizontal and, vertical angles. It was invented by Roemer, a Danish, astronomer in 1690. The instrument was used to observe, astronomical observations. Later it was modified to suit, the surveying requirements. It is primarily used for, measuring horizontal angels. Later further aditions were, made to make possible of several uses such as, prolonging a line, establishing line, levelling, measuring, the distance indirectly (tacheometry) etc., , A theodolite is said to be non-transit one if its telescope, cannot ne revolved through 1800 in a vertical plane about, its horizontal axis. Non transit theodolities are obsolete, nowadays, Designation of theodolite, The size of a theodolite is defined by its diameter of the, graduated circle of the lower plate. For example, a 25cm, theodolte means the diameter of the lower graduated, circle is 25cm., , It is sometimes referred to as universal instrument., Theodolite is very useful instrument for engineers., Classification of theodolite, Theodolites may be classified into the following two types., 1 Transit or engineer’s theodolite and, 2 Non – transit theodolite., A theodolite is said to be transit one when its telescope, can be revolved through 1800 in a vertical plane about, its horizontal axis, thus turning the telescope in exactly, opposite direction. All modern theodolites are transit type., , 111, , Copyright Free under CC BY Licence

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Construction, Draughtsman Civil - Theodolite, , Related Theory for Exercise 2. 5.70 & 71, , Main parts of vernier theodolite - I, Objectives: At the end of this lesson you shall be able to, • sketch sectional views of a theodolite, • explain main parts of theodolite, • state fundamental operations of theodolite., Main parts of a vernier theodolite, , Shifting head, , Schematic diagram of theodolite, , This device helps in exactly centering the instrument over, the station. When it is unlocked, the instrument can be, moved slightly and independently of the leveling head., , Levelling head, Levelling head is used to level the instrument horizontal., It consists of two plates:, , Therefore the instrument is first approximately centered, over the station and exact centering is done using the, shifting head., , 1 Upper tribrach plate and, 2 Trivet or Lower tribrach plate., The upper carries three levelling screws. The lower plate, also known as foot plate, is provided with a large central, hole with thread for fitting into the top of the tripod.A plumb, bob can be suspended from a hook at the lower end of, the inner spindle for centering purpose. (Fig 1& 2), , Moved slightly and independently of the levelling head., Therefore the instrument is first approximately centered, over the station and exact centering is done using the, shifting head., Lower plate and upper plate (Fig 3), , Fig 1, , It carries a circular scale which is graduated from 0° to, 360°. It is attached to the outer spindle., Upper plate is also called vernier plate. Two diametrically, opposite verniers (A and B) provided with magnifiers are, fixed to the upper plate. It is attached to inner spindle, which rotates in the outer spindle., Clamp and Tangents, Two Clamp screws and tangents are provided on the, horizontal circle and one clamp screw and tangent screw, are provided on the vertical circle They are called., 1 Upper clamping screws and its tangent, 2 Lower clamping screw and its tangent and, 3 Vertical circle clamping screw and its tangent., 112, , Copyright Free under CC BY Licence

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Lower plate can be clamped to outer spindle at any, desired position using lower clamps. The upper plate, can be clamped to the lower plate using upper clamp, screws. If the upper clamp is locked and lower clamp is, loosened, the two plates rotate together on outer spindle, without causing any change in the reading. If the upper, clamp is loosened and the lower clamped, the upper plate, rotates on its inner spindle with relative motion between, two plates. This property is used for measuring horizontal, angles., Fundamental Operations, 1 Upper and lower circles and locked together using, upper clamping screw and small differential, movement of plates is achieved using upper tangent, screw., 2 Lower plate is clamped to the outer spindle using, lower clamping screw and small differential, movement between lower plate and spindle is, achieved using lower tangent screw., 3 Vertical motion of telescope is controlled by vertical, clamping screw and small movement is achieved, using vertical tangent screw., Clamping upper plates and loosening lower clamp, the, upper and lower plates rotate as one unit relative to outer, spindle. This enables to set predetermined angles., , There are two level tubes. One on the horizontal upper, plate and another attached to the vertical vernier., Sometimes it carries two plate levels. If two plate levels, are provided, they will be at right angles to each other. A, level tube is also known as a bubble tube or spirit level, or level., It is a glass tube which is curved and sealed at both the, ends. It is filled with sensitive liquid such as alcohol or, ether. The liquid should be sensitive, non –freezing and, stable. The radius of the circular longitudinal curve of, the tube varies according to use. Bubble sensitiveness, is inversely proportional to the radius of the curvature of, the bubble tube., The bubble of the plate level is centered with help of the, foot screws. These level help to make the vertical axis, of the instrument truly vertical., The level is provided with a scale having uniform, graduations, generally of 2mm length etched on the, exterior surface of the tube. The graduations are, numbered and considered in both ways from the centre, point. Position of the bubble is determined by nothing, the positions of both the end because the bubble will, change its length with changes in temperature and the, reading of one end is not sufficient to determine the, position of the bubble, , Clamping lower plates and loosening lower clamp, the, horizontal vernier plate moves relative to lower plate. This, enables to measure angles., Level Tubes (Fig 4 ), , Construction: Draughtsman Civil - (NSQF Level -5): Related Theory for Exercise 2.5.70 & 71, , Copyright Free under CC BY Licence, , 113

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Main parts of a vernier theodolite -II, Objectives: At the end of this lesson you shall be able to, • explain working principle of telescope, • type of telescope, • state functions of main of telescope., Telescope (Fig 1 & 2), , Fig. 5 External focusing telescope, Function of telescope is to provide the line of sight., Telescope is mounted on horizontal axis (placed at right, angles to the line of collimation). Vertical circle is also, connected with telescope. It has,, i, , An eye piece (held next to the eye when sighting, through telescope, , ii A diaphragm and, iii An object glass or objective (towards object sighted), Working principle of a telescope, , Fig 6 Ray diagram of external foussing telescope, , The telescope is used to produce enlarged virtual image, of distance objects which can be easily read by human, eye. The telescope consists of two convex lenses. The, optical centre is usually located near the geometric centre, of the lens., The principle of telescope is that in a lens all rays passing, through the optical centre of the lens go straight without, any bending while the other rays get deflected and go, through the principle focus F., Types of telescope, Telescope of theodolite may be internal focusing type or, external focusing type. Now a days the most commonly, used telescopes are internal focusing type., Fig .3. Internal focusing telescope, Fig. 4 Ray diagram of internal focusing telescope, 114, , Eye piece, The eye piece lenses magnify the image together with, the cross hairs.. Ideally the eye pieces should reduce, chromatic and spherical aberration. Ramsden’s eye piece, is the most suitable eye piece and is commonly used. It, is composed of two plano-convex lenses of equal focal, length which kept equal to two-third of the focal length., The image formed by object glass in front of the eye, piece, is at a distance lesser than its focal length, and, hence eye piece magnifies the image which appeared, erected to the observer., , Construction: Draughtsman Civil - (NSQF Level 5): Related Theory for Exercise 2.5.70 & 71, , Copyright Free under CC BY Licence

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Fig 7 Eyepiece of telescope, , Fig 9 Commonly used cross hairs, , Diaphragm, The diaphragm carries the recticle containing a horizontal, and vertical hair. The diaphragm is fitted inside the main, tube by capstan headed screw. Position of the crosshairs, can be adjusted slightly (horizontally and vertically). In, modern instruments, a thin glass plate with lines ruled, or etched and filaments of dark metal deposited in them, is used as reticle. Sometimes two additional horizontal, hairs called stadia hairs are added. One above and the, other below the usual horizontal cross hair for, tacheometry surveying., , Object glass, A single lens has many defects like chromatic aberration, and spherical aberration. These defects are overcome, by using two lenses joined to form the object glass., Usually a convex lens of crown glass and a concave, lens of flint glass are joined. To minimize loss due to, refraction, the lenses are given a thin uniform coating, which has an index of refraction smaller than that of glass., Fig 10. Objective glass, , Fig. 8 Diaphragm of telescope, , Main parts of a vernier theodolite -III, Objectives: At the end of this lesson you shall be able to, • state graduations of vertical circle, • state main parts of theodolite, • differentiate a frame and frame., Vertical Circle, Vertical circle is connected to telescope and it moves, with telescope when telescope is rotated in vertical plane., The following graduations are in common use., , 1 The vertical circle is divided into four quadrants from, 0° to 90° in both the directions. The 0° -0° line is a, vertical line., 2 The vertical circle is divided into four quadrants from, 0° to 90° in both the directions. The 0º - 0º line is a, vertical line., , Construction: Draughtsman Civil - (NSQF Level 5): Related Theory for Exercise 2.5.70 & 71, , Copyright Free under CC BY Licence, , 115

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Graduation systems of vertical circle (Fig 1), , The Standards or (‘A’ Frame) (Fig 4), , Index frame (or ‘T’ frame or vernier frame) (Fig 2), Two standards resembling English letter A are fixed on, the upper plate. These frames support the telescope., They are known as standards or A frame. The horizontal, axis of the telescope is supported on this a frame. The, ‘T’ frame and vertical circle are attached to this frame., Tripod, , It resembles the English letter T and is centered on the, horizontal axis of the instrument. It consists of a vertical, arm and a horizontal arm. The vertical arm is called, dipping arm and a horizontal arm is called an index arm., Clipping arm is provided with a fork and two clipping, screws at its lower extremity. AT the top of the frame is, attached a bubble called the altitudes bubble. At the two, ends of index arm verniers C and D are fitted., , Theodolite is used by mounting it on a tripod when being, used in the field. It consist of three legs which are, provided with pointed steel shoes to get good grip on, the ground. External screw is provided on the top of the, tripod to facilitate screwing of theodolite. Nowadays, telescopic theodolite is used where accurate centering, is required., Plumb bob, A hook is provided at the lower end of the inner spindle, from which a plumb bob can be suspended. It facilitates, exact centering of theodolite over the station., , Fig 3 Vertical circle vernier, , 116, , Construction: Draughtsman Civil - (NSQF Level 5): Related Theory for Exercise 2.5.70 & 71, , Copyright Free under CC BY Licence

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Fundamental axes and geometry of theodolite, Objectives: At the end of this lesson you shall be able to, • explain fundamental axes of theodolite, • explain the classify theodolite, • explain the designate theodolite., Fundamental axes of theodolite, , Axis of the altitude level tube, , Vertical Axis, , An imaginary straight line tangential to the longitudinal, curve of altitude level at its centre., , The axis about which a theodolite is rotated in horizontal, plane is the vertical axis., , Fundamental axes of theodolite (Fig 3), , Horizontal axis ( Trunnion axis), The axis about which the telescope rotates in a vertical, Plane is called horizontal axis or trunnion axis., Line of collimation or line of sight, It is an imaginary line joining the intersection of the cross, hairs with optical centre of the object glass and its, continuation., Line of colimation (Fig 1), , Schematic diagram of fundamental axes of, theodolite (Fig 4), , Axis of telescope (Fig 2), , Geometry of the theodolite, Axis of Telescope, It is an imaginary line joining the centre of the eye piece, and the optical centre of the objective., , In a perfectly constructed theodolite, following relations, between axes of the instrument should exist., •, , The vertical axis of the instrument should be, perpendicular to the axis of the plate bubble., , •, , Line of sight should be perpendicular to the horizontal, axis., , •, , The horizontal axis should be perpendicular to the, vertical axis., , Axis of plate level bubble, An imaginary straight line tangential to the longitudinal, curve of plate level at its centre., , Construction: Draughtsman Civil - (NSQF Level - 5): Related Theory for Exercise 2.5.70 & 71, , Copyright Free under CC BY Licence, , 117

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•, , The axis of the altitude bubble tube should be parallel, to the line of sight., , Figure showing geometry of theodolite (Fig 6), , A crude figure showing geometric of theodolite, (Fig 5), , 118, , Construction: Draughtsman Civil - (NSQF Leve - 5): Related Theory for Exercise 2.5.70 & 71, , Copyright Free under CC BY Licence

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Construction, Draughtsman Civil - Theodolite, , Related Theory for Exercise 2.5.72 & 2.5.73, , Definitions and terms, Objectives: At the end of this lesson you shall be able to, • define the terms used in theodolite surveying, • state the difference between face left and face right observations, • explain least count., Definitions and other Technical Terms, , Telescope Inverted, , Centering, , When the vertical circle on the right of the telescope and, the target on telescope is down, then it is called telescope, inverted., , The process of bringing the vertical axis of theodolite, immediately over a mark or station is known as centering., This is achieved by suspending plumb bob along vertical, axis of theodolite and shifting the head., , Face left and face right observations (Fig 2), , Transiting or reversing or plunging, The process of turning the telescope in vertical plane,, about its horizontal axis through 180 0 is known as, transiting. The terms reversing or plunging are also used, sometimes for transiting., Swing, Rotating telescope in horizontal plane, about its vertical, axis is called swing. According to the direction of rotation,, there are two swings., When the telescope is rotated clockwise it is called right, swing., When the telescope is rotated anticlockwise it is called, left swing., Transit and swing (Fig 1), , The observation made keeping the vertical circle of the, instrument on the left side of the telescope is known as, face left observations., The observations made keeping the vertical circle of the, instrument on the right side of the telescope is known as, face right observations., Changing face, Process of changing face left to right or vice versa is, known as changing face., A set of observations:, It consists of two horizontal observations; one face left, and one face right., Double sighting (Fig 3), Operation theodolite twice, once with telescope in the, normal condition and another with telescope in the, reverse condition, is called double sighting., , Telescope normal, When the vertical circle on the left of the telescope and, the target on telescope is up, then it is called telescope, normal., , Least count (L.C), The smallest measurable unit is called least count., 119, , Copyright Free under CC BY Licence

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Lining In, The process of establishing intermediate points with a, theodolite on a given straight line, whose both ends are, intervisible is called lining in., Balancing In, The process of establishing intermediate points with a, theodolite on a given straight line, whose both ends are, not intervisible is called balancing in., , Unplacing and placing theodolite, Objectives: At the end of this lesson you shall be able to, • unplace the theodolite from box, • place the theodolite in the box, Taking out theodolite from the box, Open the box carefully. Ensure the correct seating of, the telescope in the box. Students may prepare a rough, sketch and stick it to the inner cover or mark the seating, position of theodolite on box, hold the upper body then, of the theodolite with the left hand and put the middle, finger of the right hand below the foot screw and gently, lift it out of the box., Placing theodolite in the box, Unscrew the theodolite from the stand and place the, theodolite carefully inside the box. Check these things, while placing theodolite in the box:, 1 Loosen all the clamps., 2 Cover the objective glass., 3 Vertical circle on left side of the surveyor., 4 One foot screw on the top, facing the surveyor and, the other two rest on support provided in the box., , 120, , Construction: Draughtsman Civil - (NSQF): Related Theory for Exercise 2.5.72 & 73, , Copyright Free under CC BY Licence

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Construction, Draughtsman Civil - Theodolite, , Related Theory for Exercise 2.5.74, , Prolonging a line, Objectives: At the end of this lesson you shall be able to, • state methods for prolonging a line, • compare methods for prolonging a line, • state most suitable method for prolonging a line., Prolongation of a straight line, , Method I, , First fix a line AB. Set up the instrument over the end B,, instead of A. Shift the instrument to C and backsight B., Transit the telescope and locate D. the process is, repeated until the line is prolonged to the desired, distance. This process is more accurate than the first, method because the error is not carried over the other, spans., , Method II, , Method III, , Method III, , Prolonging a line by third method (Fig 3), , Sometimes a survey line has to extend or prolong to a, considerable distance. There are three methods for, prolonging a line:, , Each method is illustrated below, Method I, Prolonging a line by first method (Fig 1), , Set up the instrument over the end A, and sight the end, B of line AB. Arrest the horizontal motion of the instrument, and locate another point C at a considerable distance, from B on the prolongation of line. Shift the theodolite to, B. Following above steps locate another point D. The, process is repeated until the line is prolonged to the, desired distance., This method will result in cumulative errors, if the, instrument is not in adjustment, Method II, , This method is also called double sighting. First, fix a, line AB. Set up the instrument over the end B. Backsight, A with face left. Plunge the telescope and locate. C,, change face of the instrument. Backsight A again, plunge, the telescope and locate C2. The point C1 and C2 only if, the instrument is out of adjustments. The mean of the, location C1 and C2 is the desired point C. The process is, repeated until the line is prolonged to the desired, distance., his method is used when the instrument is suspected, with improper adjustments. The error is doubled on, reversal of the telescope and the mean of the two location, becomes the desired location of the point., , Prolonging a line by second method (Fig 2), , 121, , Copyright Free under CC BY Licence

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Running a straight line between two points, Objectives: At the end of this lesson you shall be able to, • classify methods of runing a straight line according to field conditions, • explain how to run a line when both ends are intervisible, • explain how to run a line when both ends are not intervisible but visible but visible from an intermediate, point, • explain how to run a line when both ends are not visible from any intermediate point., Running a straight line, Sometimes a surveyor is required to establish a number, of intermediate points between two established points., Three cases are there for unning a line according to field, conditions., •, , Both ends intervisible., , • Both ends not intervisible but visible from an, intermediate point., •, , Both ends not visible from any intermediate point., , 6 Now set up the instrument at the new estimed position, C2, closer to C (Located point may be the required, point, C if not, follow the steps given below)., 7 Take a backsight again on A. Plunge the telescope, and locate another point B2, 8 Measure the distance B2 B and determine C2C by, which the instrument has to be shifted laterally so, that the point is on the line AB C2C = (B2B/L) x I, 9 Repeat the steps until the line of sight strikes B When, the telescope is plunged., Balancing – In (Fig 2), , Both ends intervisible, In such field condition, set the instrument at any of the, end stations. Arrest the horizontal motion of the, telescope. Direct a person holding the ranging rod to the, required position along the line. This method is called, lining – in., Following figures shows 3 points located between already, established points A and B., Lining in (Fig 1), , Both ends not intervisible but visible from an, intermediate point, This method of locating intermediate points is called, balancing – in. A typical case arises when a rising ground, exists on the straight line joining end stations., The procedure for locating intermediate point in such, case is explained with the figure., 1 Set up the instrument at a point close to the line AB;, Let it be., 2 Set the instrument on, 3 Sight the point A., 4 Plunge the telescope and locate a point., 5 Measure the distance B1 B and determine C1 C by, which the instrument has to be shifted laterally so, that the point is on the line AB C1 C= (B1 B/L) x I., 122, , Then the instrument station is the required intermediate, Point C on line AB., Locate the point vertically below the centre of the, instrument using plumb bob or optical plummet., Double sighting (Fig 3), If the intermediate point is to be established with high, precision or when the instrument is in improper, adjustment, the intermediate point is established by the, method of double sighting. Two points and are located, by both face observations. Measure the distance and, find the midpoint of which is the required point C., Both ends not visible from any intermediate point, When the area is thickly wooded or hilly, the end of the, line will not be intervisible from any intermediate points., , Construction: Draughtsman Civil - (NSQF Level - 5): Related Theory for Exercise 2.5.74, , Copyright Free under CC BY Licence

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In such conditions, for establishing intermediate point, on a given straight line, random line method is adopted., The method is explained below., , 7 Measure off the distance which is equal to (AD/Ac x, BC along the line of sight dD., 8 The point D will be on the line AB. Other intermediate, points, E and F are also established in the similar, manner (angle to be set at ‘e’ and ‘f’ is θ and using, similarity property of triangle, find the distance to be, measured off at ‘e’ and ‘f’., Check whether, D, E and F are in the line AB, when the, instrument is at any of the end stations. Shift the eccentric, point, if it does not lie exactly on the line AB., Random line (Fig 4), , 1 Locate a point C near to B from where both A and B, are visible., 2 Set up the instrument at C and measure the angle, ACB, let this angle be θ., 3 Measure the distances AC and CB., 4 Locate a convenient point ‘d ‘ on the line AC., 5 Set up the instrument over ‘d’, 6 Lay off the angle AdD equal to θ, , Intersection of two straight lines, Objectives: At the end of this lesson you shall be able to, • explain method I to find out intersection point of two straight liens, • explain method II to find out intersection point of two straight lines, Intersection of two straight lines, , •, , Set up the instrument at one end of the line, say at A, on AB and sight B., , Intersection of two straight lines can be located using a, theodolite., , •, , Clamp both the plates and arrest horizontal motion, of the telescope., , Case I, , •, , Estimate approximate intersection point, X, of two, lines and fix two points ‘W’ and ‘Y’ a small distance, apart on either side of the estimated point., , •, , Stretch a string between the points ‘W’ and ‘Y’, , •, , Shift and set up the instrument at C of the line CD., , •, , The point of intersection X is marked on the string, where the line of sight cuts the string., , Intersection of two lines, case I (Fig 1), , Case II, Intersection of two lines, case II (Fig 2), Set up the instrument at A and sight B., Fix two points W1 and Y1 on prolongation of AB on either, side of the estimated position of the intersection point., Construction: Draughtsman Civil - (NSQF Level -5): Related Theory for Exercise 2.5.74, , Copyright Free under CC BY Licence, , 123

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Stretch a string between them. Now shift the instrument, to C and sight D. The prolongation of CD cuts the string, at the intersection X of the two lines., To achieve better accuracy in locating the intersection,, double sighting can be used in both the above cases., , 124, , Construction: Draughtsman Civil - (NSQF Level -5): Related Theory for Exercise 2.5.74, , Copyright Free under CC BY Licence

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Construction, Draughtsman Civil - Theodolite, , Related Theory for Exercise 2.5.75, , Temporary adjustments of theodolite, Objectives: At the end of this lesson you shall be able to, • set up and perform centering of the instrument, • level up the theodolite, • eliminate parallax., Temporary Adjustments of a Theodolite, Temporary adjustments are that adjustments required, at every new set up of the theodolite. Following temporary, adjustments are required for a new set up of a theodolite, before starting the work. They are:-, , Levelling Up, Levelling operation is performed to make the, vertical axis of the instrument truly vertical and, pass through the station, , Focussing, , 1 Setting up, , Focussing is done to eliminate parallax error., , 2 Centering, 3 Levelling up, , Focussing the eyepiece, , 4 Focussing, a Focussing the eyepiece, b Focussing the objective., , This is done by holding a white paper 15cm in front of, the objective and turning the eyepiece in or out until the, cross hairs are seen sharp and district., , Setting up, , Focussing the objective, , Initially tripod is set up at a convenient height over the, station spreading and fixing three legs firmly on the, ground. Fix the instrument over the tripod. Bring the, leveling screw at the middle of the run. Then the, instrument is approximately levelled by eye judgement., Some instruments are provided with a small circular, bubble on the tribrach to check the horizontal level., , Object to be sighted is focused to bring the image in the, plane of the cross hairs., , Centering will disturb if there is considerable, dislevelment, Centering, Centering is achieved by suspending plum bob with a, string attached to the hook fitted to the bottom end of, the vertical axis. Approximate centering is done by, moving the leg radially and circumferentially. Accurate, centering by finer movements is done by shifting the, head, unlocking the shifting head clamp., , Move the eye up and down or sideways to check whether, the cross hairs have any relative movement with respect, to the object sighted., Parallax is a condition that there exists relative movement, between the cross hairs and the object sighted. This, condition arises when the focusing lens is not in its proper, position. Parallax can be eliminated by refocusing lens, in proper position., Fig 1 Parallax – Image not formed in the plane of cross, hairs ( a OR b). Refocus`sing brings the lens in proper, position and parallax eliminated (c ), , Centering is done to place the vertical axis, exactly over the station., , 125, , Copyright Free under CC BY Licence

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Permanent adjustments, Objectives: At the end of this lesson you shall be able to, • list the permanent adjustments, • explain relationship satisfied by adjustments, • explain tests and adjustments., Permanent adjustments, The fundamental lines (see the terms) of theodolite have, inter-relationships amongst each other. Manufactures of, theodolite take care of this while manufacturing, theodolite., , 6 Vertical arc test – to make the vertical circle indicate, zero when the line of sight is perpendicular to the, vertical axis., Plate level test, Relation established, , Axes of theodolite (Fig 1), Axis of the plate level tube should be perpendicular to, the vertical axis of the instrument., Bubble must remain at the centre of its run during, complete revolution if the instrument is in perfect, adjustment. This test is used to check whether the plate, level axis is perpendicular to the vertical axis of the, instrument., Test, To test, the instrument is levelled and the telescope is, rotated through 180º. If the bubble runs out of the centre,, the adjustment is out of order. If the bubble is out of the, centre, count the number of graduations on the bubble, tube., The relationships between fundamental lines are, explained in the geometry of theodoite. However the, prolonged use of theodolite and mishandling of, instrument in field will make the fundamental lines, relations altered, there by observations become, erroneous., So, the instrument has to be checked for these relations, and if found erroneous the instrument should be correctly, adjusted before using it for recording the observations., Such adjustments are called permanent adjustments., , Adjustment, Correct the error by means of pair of leveling screws, and the remaining correction is made by means of, capstan headed screw provided at the end of the level, tube., Cross-hair ring test (Fig 2), , The tests and permanent adjustments are done in the, following order., 1 Plate level Test – to make the plate bubbles central, to their run when the vertical axis of the theodolite is, truly vertical., 2 Cross – hair ring test – to make the vertical and, horizontal cross hairs lies in a plane perpendicular to, the horizontal axis., 3 Collimation test – To make the line of sight, perpendicular to the horizontal axis., 4 Spire Test – To make the horizontal axis, perpendicular to the vertical axis., 5 Bubble tube adjustment – To make the telescope, bubble central when theline of sight is horizontal., , 126, , Relation established, The vertical cross-hair should lie in a plane perpendicular, to the horizontal axis., , Construction: Draughtsman Civil - (NSQF Level -5): Related Theory for Exercise 2.5.75, , Copyright Free under CC BY Licence

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Test, , Change face of the instrument and bisect the first point., Transit the telescope., , Instrument is levelled. The telescope is directed towards, a plumb bob string at rest. The string is bisected and, telescope is rotated slightly in a vertical plane. If the, relation is in perfect condition, the image moves off the, cross hair it means the relation is not in adjustment., , If the line of sight does not passes through the already, fixed point then the line of sight is perpendicular to the, horizontal axis., If the line of sight pass through the point, the adjustment, is done as follows., , Adjustment, To adjust the vertical cross hair, loosen all four capstan, screws on the cross-hair ring. Rotate the ring carefully, so that the image of the string and the vertical cross hair, coincide. The screws are then tightened., Note: If the vertical cross hair is set perpendicular to the, horizontal axis, the horizontal axis is automatically made, horizontal., Collimation in azimuth test (Fig 3), , Adjustment, Fix the new point. Measure the distance between points,, Measure a quarter of the distance from the last point., Adjust the vertical hair by means of two opposite capstan, headed screws so that the line of sight passes through, the quarter distance. Repeat the test till line of sight, passes through the same point in both face observations., The instrument is at point I, the back sight is point A, and, point F1 is set at the foresight. Line n is perpendicular to, the trunnion axis, as the line of sight should be. The line, of sight is deflected from line n by an angle. The error in, the back sight reverses direction in the foresight. The, foresight direction is in error by two times the deflection, error (2), Turn to the same back sight in inverted position. Plunge, the scope again, and in direct position, set another mark, at the foresight, F2 as shown in the centre of the picture., The angle between the two foresight marks is four times, the deflection error. It is corrected by moving the crosshair, horizontally., , Relation Established, , Foresight error is four times the deflection error, (Fig 4), , The line of sight should be perpendicular to the horizontal, axis., If the relation is in adjustment, the line of collimation will, generate a plane when the telescope is revolved in, vertical plane. If this relation is not in adjustment, the, line of collimation will generate a cone with the horizontal, axis., Line of sight is making an angle with the horizontal axis, so a cone is generated when telescope is revolved in, vertical Plane., Exaggerated figure showing line of sight not being, perpendicular to the horizontal axis., , Spire Test, Relation Established, , Test, The instrument is set up and levelled at a point in an, open field so as to have an unobstructed view of 100m, on either side of the instrument. Set up the instrument at, midway, telescope in normal condition. Sight a point, transit the telescope and fix another point on the same, line., , The horizontal axis should be perpendicular to the vertical, axis., This adjustment ensures that the line of sight revolves, in a vertical plane perpendicular to the horizontal axis, when the instrument is levelled., , Construction: Draughtsman Civil - (NSQF Level -5): Related Theory for Exercise 2.5.75, , Copyright Free under CC BY Licence, , 127

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Trunnion (Horizontal) axis makes an angle with the, horizontal., Exaggerated figure showing horizontal axis not being, perpendicular to the vertical axis., Horizontal axis makes an angle α with the horizontal., (Fig 5), , Test, Set up the instrument near any tall object which has a, well defined point available at 60º to 70º vertical angle., With face left, sight the well defined point. Lower the, telescope after arresting the horizontal movement of, telescope and find foot of the point of the ground. Change, face of the instrument and repeat above procedure. If, foot of the point sighted is same in both face, observations, then the horizontal axis is perpendicular, to the vertical axis and if not the instrument needs, adjustment., Adjustment, Distance between foot distance is measured and mark, half the midway between the distance. Centre point is, bisected and raise the telescope to sight the point, but it, in an error by a half the distance foot of the point., , Fig. 9 Find foot of S by face right observation, , One end of the horizontal axis is moved with the adjusting, screw until the line of sight bisects the point. Repeat the, test and check the adjustment., Figure 6 showing well defined point ‘S’ is, sighted and foot F 1 and F 2 established at, ground., Spire test (Fig 6), , Vertical Circle index test, , The deflection error, refer the difference between the, backsight and foresight directions. It is not a measure, of the axis tilt. An angle of 2 will be subtended between, the two foresights., Fig 7 ‘s’ is sighted, , Relation Established, The axis of the bubble tube attached to the telescope, should be parallel to the line of sight. This is done so, that the vertical circle reads zero when the telescope is, horizontal., , Fig. 8 Find foot of S by face left observation., 128, , Construction: Draughtsman Civil - (NSQF Level -5): Related Theory for Exercise 2.5.75, , Copyright Free under CC BY Licence

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Test, , Adjustment, , Set the vertical vernier to zero. A staff is held vertical at, about 60m from the instrument and the reading is taken, by face left observation. Then the face is changed and, the staff is read again. If there is an error, the face reading, will be different., , The telescope is set to read the mean of the two staff, readings. Then the vertical circle should be brought back, to read zero using the clip screws., , Fig 10. Vertical Circle Index Test, , Desired relation, , Vertical arc test, , When the line of sight is perpendicular to the vertical, axis the vertical circle should be zero., Test, Centre the altitude bubble on the telescope. The zero of, the vernier of the vertical circle should coincide with the, zero on the main scale of the vertical circle. If it doesn’t, coincide, it needs adjustment., Adjustment, The capstan head screws are loosened and the vernier, is moved till the zero coincides with that of the main scale., , Construction: Draughtsman Civil - (NSQF Level - 5): Related Theory for Exercise 2.5.75, , Copyright Free under CC BY Licence, , 129

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Construction, Draughtsman Civil - Theodolite, , Related Theory for Exercise 2.5.76, , Instrumental errors, Objectives: At the end of this lesson you shall be able to, • classify errors, • state instrumental errors, • state how to eliminate or minimize instrumental errors., Errors, , Elimination: Taking the average of observations on face, left and face right., , The sources which cause error in the measurements, are classified as:, 1 Instrumental, , Eccentricity of liner and outer plate axes, Vertical axes of the inner spindle (carries vernier) and, outer spindle (carries horizontal circle) should coincide, otherwise error will occur., , 2 Natural, 3 Personal, , Elimination: Reading both verniers are taking mean of, both the vernier readings., , Instrumental errors, Instrumental errors are caused due to fundamental axes, going out of the adjustments., Causes, 1 Wear and tear of components due to prolonged use, of the instrument., 2 Manufacturing defects., , Eccentricity of Verniers, If verniers are not exactly diametrically opposite, ie.,180º, to each other the two vernier readings will not differ by, 180º. However, since the difference is constant, both the, vernier readings will give same angle. Hence, this, manufacturing defect has no effect on the observations., Imperfect Vertical Circle Vernier, , Plate level axis not being perpendicular to vertical, axis, If this fundamental relation is out of order, the actual, measurements we are observing is in vertical plane, instead of horizontal plane. It will affect seriously in, vertical angle measurements and in calculation of, elevation., , When the line of sight is not horizontal, vertical circle, vernier will not show zero reading and will make the, vertical angle error., Elimination, Reading are taken on both faces., Imperfect Graduations, , Elimination, Correcting by permanent adjustments., Trunnion axis not being perpendicular to vertical axis, The Horizontal angls and vertical angles will be, erroneous if this relation is out of order., Elimination, , If graduation on the horizontal circle are not uniformly, spaced or if the scale is not properly centred, the, horizontal angle readings will not be correct. Error is, greatest when observations are taken on different vertical, angles and different lengths., Minimizing error: Taking observations at different, portions of the horizontal scale and taking mean of the, observations and measuring angles by repetition method., , Taking the average of observations on face left and face, right., Line of collimation not being perpendicular to, trunnion axis, Line of collimation not revolve in a vertical plane when, the telescope is raised or lowered if line of collimation is, not being perpendicular to the trunnion axis., 130, , Copyright Free under CC BY Licence

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Natural errors, Objectives: At the end of this lesson you shall be able to, • state natural errors, • state how to minimize natural errors, • state how to eliminate natural errors., Natural Errors, , Avoiding Error, , These errors are caused due to natural elements such, as wind, temperature and atmospheric conditions., , 1 Suspend the work when the wind is strong., , Temperature Effect, , 2 Shelter the instrument from the wind., Refraction Effect, , Exposure of instrument to the sun may cause expansion, of different parts of the instrument. Unequal expansion, of the instrument parts will result in erroneous, observations. Bubble will move to the heated portion of, the theodolite., Minimizing Error, , Refraction causes sighting the object difficult., Avoiding Error, Avoid line of sight passing closely through structures such, as buildings, smoke stacks, bitumen surface and surface, which radiate heat., , Exposure of instrument is avoided by using surveyor’s, umbrella., , Unequal Settlement of tripod, , Shelter the instrument from the rays of the sun., , If the ground is soft, tripod will settle and errors will creep, on the observations., , Wind Effect, , Avoiding Error, , Exposure of the instrument to the heavy wind cause, vibrations of different parts of the theodolite causing error, in observations., , 1 Fix tripod on firm ground., 2 Press the tripod legs sufficiently into the ground., 3 Use triangular frame., 4 Driving stakes on soft ground to receive tripod legs., , Personal errors and mistakes, Objectives: At the end of this lesson you shall be able to, • state personal errors, • state how to eliminate or minimize personal errors, • state common mistakes while operating theodolite., Personal Errors, , Error due to inaccurate levelling, , Personal errors arise from limitations of human eye in, setting up the instrument and taking observations., Sometimes surveyor overlooks some of his limitations, resulting in personal errors., , The error is small when the sights are nearly level, but, may be large for steep inclined sights., , Error due to inaccurate centering, , Error may be eliminated or minimized by frequent, checking of the position of the bubble centre, and if, necessary, it should be re-centered., , If the instrument is not set up exactly over the station, it, will cause error when measuring horizontal angles. The, magnitude of the error is directly proportional to the, direction of instrument and inversely proportional to the, length of the sight. Angular error is about 1’ when the, error of centering is 1 cm for a length of sight 35 m., , Slip in Screws, , Error may be kept in negligible limit by taking reasonable, care. Time should not be wasted in setting up of the, instrument when the sights are long., , The error due to slip is avoided by tightening all the, screws., , Slip may occur if the clamp screws are not properly, tightened or shifting head is not properly tightened or, when the instrument is not properly fixed to the tripod, head. Slip cause error., , Construction: Draughtsman Civil - (NSQF Level -5): Related Theory for Exercise 2.5.76, , Copyright Free under CC BY Licence, , 131

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Improper use of screws and tangents, This error is introduced by improper use of the screws, and tangents. For sighting left hand object, use lower, clamp screw and its tangent and for sighting right hand, object, use upper clamp screw and its tangent., For sighting an object after setting pre-determined angle,, use lower screw and its tangent. For measuring, horizontal angle, use upper screw and its tangent., Final bisection of the object should be achieved using, slow motion screw. No slow motion screws work until, corresponding clamp screws have been tightened., , Error can be minimized by bisecting the lower portion of, the object and accurately centering the vertical cross hair., Level bubble not centered, The position of the bubble centre should be checked, frequently, and if necessary, it should be re-centered., Parallax, Parallax exists due to imperfect focusing of the eye piece, and objective glass., Take reasonable car while focusing to minimize the error, due to parallax., , Improper setting and reading of the verniers, Mistakes, An error in reading vernier occurs., If the observer does not use a magnifying glass., , The common mistakes or blunders which the surveyors, generally make due to carelessness are:, , If the observer does not look radially along the, graduations when reading the verniers., , 1 Misreading the vernier., , If the observer does not know how to read the vernier. If, the vernier divisions and lines are not legible., , 3 Sighting the wrong signal., , Proper care should be taken to minimize these types of, errors., , 5 Setting up the instrument over the wrong station., , Inaccurate sighting, , 7 Missing to mention right or left deflection angle., , Great care should be taken to bisect accurately, if the, station to be observed is closer. Usually sights are taken, on the upper position which is visible from the instrument., , 132, , 2 Reading the wrong vernier., , 4 Turning the wrong tangent screws., , 6 Booking wrong values of the readings., , 8 Forgetting to deduct the observation from 360º in left, deflection angle. Utmost care should be taken in the, field to avoid above mistakes., , Construction: Draughtsman Civil - (NSQF Level -5): Related Theory for Exercise 2.5.76, , Copyright Free under CC BY Licence

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Construction, Draughtsman Civil - Theodolite, , Related Theory for Exercise 2.5.77, , Reading a theodolite, Objectives: At the end of this lesson you shall be able to, • find least count of the main scales, • find least count of the instrument, • read a thodolite., Reading a thodolite, Mainly two verniers are provided in a theodolite for, measuring horizontal and vertical angles. For horizontal, angles, readings on the main scale (lower plate) and, verniers (upper plate) are observed. For vertical angles,, the main scale on the vertical circle and the verniers on, the T frame are observed., Two verniers A and B are provided on the horizontal circle, and C and D are provided on the vertical circle. The, main scale for horizontal circle is graduated from 0º to, 360º. Generally each degree on the main scale is divided, into three parts, hence the least count or the smallest, division of the main scale is,, , Graduations are marked in clockwise direction and figures are engravedat 100 interval., One division on main scale is 20’, One division on vernier scale is 20”, Reading = M.S.D + (V.S.D x L..C), From the following enlarged view of figure 1 it is, understood that zero of vernier scale is in between 22°, 40’00” and 23° 00 00”., Enlarged view of vernier (Fig 2), , L.C = (1/n) x smallest division of the main, scale, n is the number of dvisions = (1/3)x 60’, =20’20 is the L.C of the main scale., For finding L.C of the instrument above formula is used., Smallest division of the main scale is 20’ and n is 60, divisions. Sixtieth division of the vernier coincides with, the fifty ninth division of the main scale, hence 60, divisions., L.C = (1/n) x smallest division of the scale, n is, the number of divisions = (1/60) x 20’ = 20" 20", is the least count., Least count of the instrument is 20”, For minimizing error observation due to instrumental, error, reading in both the verniers A and B are taken and, the mean of the two readings is used., , From the following enlarged view of figure 1 it is, understood that forty fifth vernier division exactly, coincides with a man scale division., So reading = 22 °40’ 00” + (45 x 20”) = 22°55’00”, Enlarged view of vernier (Fig 3), , Vernier (Fig 1), , 133, , Copyright Free under CC BY Licence

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Note, 1 Read vernier eliminating parallax., 2 No need to count vernier division. Read the vernier, division directly and add this to M.S.D, In the above example it is 15’00” (45 x 20”, = 900”). Add this value to the M.S.D., = 22°40’00” + 15’ 00” = 22° 55’ 00”, , While observing an angle it is noted that zero of vernierr, lies between 78° 00’ 00” and 78°20’ 00” and 13th vernier, division coincides with the main scale. L. C of, instrument is 20”. what is the angular value?, Solution, Angular value, , = 78°20’00” + (20” x 13), = 78° 00’ 00” + 260”, = 78° 00’00” + 4’20”, = 78°04’ 200”, , Theodolite - measuring horizontal angle - ordinary method, Objectives: At the end of this lesson you shall be able to, • explain ordinary method, • state advantages of ordinary method, • point out things to remember while working., Ordinary Method, , Advantages of ordinary method, , A single set of observations are made for measuring a, horizontal angle between any two points at a station in, this method (Fig.1), , 1 Errors due to eccentricity of the spindles are, eliminated by reading both the verniers., 2 Errors due to eccentricity of the verniers are eliminated, by reading both the verniers., Point to remember, 1. Carefully clamp and unclamp screws and tangents., , 2. Utmost care should be taken to avoid errors and, mistakes while operating theodolite., 3. Usually degree, minutes and seconds are measured, at vernier A and Minutes and seconds in Vernier B., Fix two station, P and Q on the ground and set up the, instrument at the point “O’. Perform all temporary, adjustments. Set vernier A 00º00’00". Sight the left hand, station. Loosen the upper clamp, sight the right hand, station and observe reading. Change face of the, instrument and take another set of readings. The mean, of the face left and face right observations is the final, required angle. Procedure explained in the given figure, and a table is also given to show how to tabulate., , 4. Theodolite should swing in clockwise direction (Right, swing) for face lit observation and swing in, anticlockwise direction (Lect swing) for face right, observation., 5. Telescopes cannot move relative to graduated circle, when upper screw is clamped and lower screw is, unclamped but can rotate in horizontal plane., 6. Telescope moves relative to graduated circle and can, rotate in horizontal plane also when upper screw is, unclamped and lower screw is clamped., , Theodolite - measuring horizontal angle - repetition method, Objectives: At the end of this lesson you shall be able to, • explain repetition method, • state advantages of repetition method, • state errors which are not eliminated., Repetition Method, This method is used to measure a horizontal angle, accurately. In this method same angle is measured, repeatedly in both face observations instead of single, 134, , observations. Mean of the face left and face right, readings after dividing by the number of repetitions, is, the final measured value of the angle., , Construction: Draughtsman Civil - (NSQF Level -5): Related Theory for Exercise 2.5.77, , Copyright Free under CC BY Licence

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Fix two staions, P and Q on the ground and set up the, instrument (Fig) at the point, ‘O’. Perform all temporary, adjustments. Set vernier A 00º00’00". Sight the left hand, station (Fig 1) chose the upper clamp, sight the right, hand station and observer reading. Without changing, the reading observed, turn the telescope and sight ‘P’, , Measure the angle again, which will read twice the first, angle. Repeat the process for required number of, repetitions., , Suppose that, for measuring a horizontal angle θ, ‘n’ times, repetitions are done. Then angle θ = (n x θ) ÷ n., , 2 Displacement of signal, , Advantages of repetition Method, 1 Error due to imperfect graduations are minimized by, reading on different parts of the graduated circle., 2 Errors, due to eccentricity of the spindles are, eliminated by reading both the verniers., 3 Errors due to eccentricity of the verniers are eliminated, by reading both the verniers., 4 Error due to line of collimation not being perpendicular, to the horizontal axis is eliminated by taking both the, face left and face right observations., , Change face of the instrument and repeat above steps, (Fig.2). The mean of the face left and face right, observations is the final required angle., , 3 Vertically of vertical axis, Points to remember, 1 For ordinary works, 3 repetitions are sufficient., 2 For precise work, 5 & 6 repetitions are done., 3 Care should be taken if reading exceeds 360º, 4 Carefully clamp and unclamp screws and tangents., 5 Utmost care should be taken to avoid errors and, mistakes while operating theodolite., Face left, right swing observation, , 5 Error due to inaccurate bisection is compensated, because many observations are taken., , Example, , 6 Possible to obtain values lesser than least count of, the instrument., , Mean of two readings (Fig 2), , Errors which are not eliminated by this method, 1 Slip, Construction: Draughtsman Civil - (NSQF Level -5): Related Theory for Exercise 2.5.77, , Copyright Free under CC BY Licence, , 135

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No. of repetitions, ∠147º 56’50", , =3, , No. of repetitions, , = 3, = ∠147º 56’50" is the angle after, 3 repetitions., , is the angle after 3 repetitions., , Face right, left swing observation (Fig 3), Means of two observations is the final angle =, Mean of two readings, , Theodolite - measuring horizontal angle - reiteration method, Objectives: At the end of this lesson you shall be able to, • explain reiteration method, • point out things to remember, • check and adjust closing the horizon error., Reiteration Method, This method is useful for measuring precisely a number, of horizontal angles from a single station point. Suppose, from a station ’O’, angle’ POQ, QOR, ROS and SOP are, to be measured. After setting the vernier A, 00º00’00",, sight the initial station P. Unlock the upper clamp and, swing telescope clockwise ( left swing) and successively, bisect the stations Q,R, and S and measure angles, accurately. Tabulate it correctly. Finally close the horizon, by sighting initial station P. When closing horizon (the, angle between the last station and first station), the final, reading should be same as initial reading. If large, discrepancy is found, the whole work should be, repeated., , observations is required angle. Sum of all the four angles, to check whether the sum is 360º. If the error is small it, is distributed equally among all the angles and the, corrected angles are obtained., More precision can be obtained by taking ‘n’ set of, readings and averaging the observations., Points to Remember, 1 While bisecting stations after sighting initial station, use only upper clamp screw and its tangent., 2 For face left observation, turn telescope clockwise, and for face right observation, turn telescope, anticlockwise., , Change face of the instrument and swing telescope, anticlockwise (right swing) and bisect the stations., Measures angles accurately and tabulate it., , 3 Carefully tabulate face right observation because last, station will bisect first., , Determine ∠QOR by deducting ∠POQ from ∠POR., Thus determine the remaining three angles separately, for both face observations. Average of the two face, , 5 Angles are corrected angles after checking and, adjusting for horizon closing (if found any, discrepancy)., , 136, , 4 Mean angles are checked for closing the horizon., , Construction: Draughtsman Civil - (NSQF Level -5): Related Theory for Exercise 2.5.77, , Copyright Free under CC BY Licence

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Measuring vertical angle, Objectives: At the end of this lesson you shall be able to, • define vertical angle, • differentiate angle of elevation and angle of depression, • explain how to measure vertical angle., Measurement of Vertical Angle, A vertical angle is defined as the angle between the line, of sight and a horizontal line, at a station in vertical plane., If the angle measured is above the horizontal line, then, it is called angle of elevation. Angle of elevation is a, positive angle (+), If the angle measured is below the horizontal line, then it, is called angle depression. Angle of depression is a, negative angle (-)., The method of measuring vertical angle varies according, to the type of the instrument used. Engineer’s transit, measures vertical angle with respect to horizontal line., Electronic theodolites can measure vertical angle with, respect to horizontal line or with respect to zenith., Set up the instrument at the station. Perform all the, temporary adjustments. The altitude bubble is set to its, centre of run for all positions of telescope. To do this, follow the given steps., 1 Turn the instrument so that the altitude bubble is, parallel to the line joining any two foot screws., 2 Bring the bubble to its centre of its run by turning the, levelling screws either inwards or both outwards., 3 Turn the telescope through 90º so that the altitude, bubble 1st perpendicular to the line joining the above, two levelling screws. Bubble table over the third foot, screw., 4 Bring the bubble of the altitude level again to centre, of its run by turning the IIIrd screws., 5 Turn back the telescope through 90º so that the, altitude level is IInd to the 1st two screws., , Point to remember, 1 Carefully read Venier C and Vernier D, 2 Signs of angles should be noted down very carefully., , 6 Repeat above steps until the altitude bubble remains, central in both the positions., , To eliminate or minimise errors due to in adjustments of, the instrument, both face readings should be taken., , 7 Bubble will remain central if the instrument is in, permanent adjustments., , Angle of elevation, <POP’ = + 09º57’10", , The object to which the vertical angle is required is, bisected using the vertical clamping screw and its tangent screw. The reading on the vertical circle is now read., Change face of the instrument and take another reading., Mean of the readings is the vertical angle., , Angle of depression, <POP’ = - 09º57’10, Included vertical angle, <POP” = <POP’ +<POP”=, 19º54’20”, , Construction: Draughtsman Civil - (NSQF Level -5): Related Theory for Exercise 2.5.77, , Copyright Free under CC BY Licence, , 137

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138, , Construction: Draughtsman Civil - (NSQF Level -5): Related Theory for Exercise 2.5.77, , Copyright Free under CC BY Licence, , Sight, To, , 0, , P, , P, , P, , 0, , 0, , Sight, to, , 0, , Instrument, at, , Instrument, , -09, , +09, , 00, , 0, , ', , 57, , 57, , 00, , ', , C, , '', , A, , ', , B, , 20, , 20, , 00, , '', , Face left, , '', , 57, , 57, , 00, , ', , D, , '', , 00, , 00, , 00, , 0, , ', , -09, , +09, , 00, , 0, , Mean, , 57, , 57, , 00, , ', , Mean, , 10, , 10, , 00, , ', , Face Left, , '', , 1, , 0, , ', , '', , Horizontal, Angle, 0, , Face Right, , ', , A, '', , -09, , +09, , 00, , 57, , 57, , 00, , Vertical, Angle, , 10, , 10, , 00, , -09, , +09, , 00, , 57, , 57, , 00, , C, , 00, , 00, , 00, , ', , 56, , 56, , 00, , D, , B, , 40, , 40, , 00, , '', , Left Swing, , Measurement of vertical Angle, , No. of, Repetitions, , No of, Repetitions, , Right Swing, , ', , '', , -09, , +09, , 00, , 56, , 56, , 00, , Mean, , 56, , 56, , 00, , Face, Left Right, , 0, , Mean, , Table for entering readings to measure vertical angle, , 1, , No. of, Repetitions, , ', , -09, , +09, , 00, , 56, , 56, , 00, , Vertical, Angle, , 0, , 50, , 50, , 00, , '', , No of, Horizontal, Repetitions Angle, ', , '', , 00, , -09, , 57, , 57, , 00, , Average, Vertical, Angle, , +09, , 0, , 00, , 00, , 00, , Rough, Sketch, , Average, Rough, Horizontal Sketch, Angle

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Deflection angle & Direct angle, Objectives: At the end of this lesson you shall be able to, • state deflection angle, • differentiate right deflection angle and left deflection angle, • state direct angle, • differentiate deflection angles and direct angles., Theodolite is used for various kind of operations in the, field. Measuring deflection angle, direct angle, prolonging, a line, running a straight line are some of them., Operations using theodolite is explained in the, forthcoming lessons., , Points to remember, , Horizontal angle can be measured by any of the 3, methods explained earlier, depending upon the, conditions., , 3 The numerical value of the deflection angle must, always be followed by ‘R’ or ‘L’ .R is for right deflection, angle and L is for left deflection angle., , Deflection angle, , 4 Measure bearing of a traverse line, if there is no, known coordinates for the traverse., , Angle between the preceding line and the succeeding is, called deflection angle. The deflection angle vary, between 00 and 1800. This type of angles is very useful, in open traversing. Such a alignment of highways,, railways, canals etc., , 1 Right deflection angle itself is the value of the angle., 2 The angle observed on scale deducted from 3600 is, the value of the left deflection angle., , Direct Angles (Fig 2), , Right deflection and left deflection angle (Fig 1), , Angles measured clockwise from a backsight to the, previous line are called angles to the right or direct angles., The direct angles vary between 0ˆ and 360ˆ. This type, of angles are very useful both in open traverse and, closed., The angle measured in clockwise direction is called right, deflection angle., The angle measured in anticlockwise direction is called, left deflection angle., The measurement of deflection angles is done by taking, a backsight on the previous station with zero reading on, one of the verniers. Then the telescope is transited and, turned clockwise or anticlockwise as the case may be., , Accuracy of the values can be improved by taking, repeated readings. The angular closure is checked by, calculating azimuths from known lines (AB and EF in, the following figure)., Points to remember, 1 Rotation should always be clockwise from the, backsight., 2 Measure bearing of a traverse, line, if there is no, known coordinates for traverse., , Accuracy of the values can be improved by taking, repeated readings. The angular closure is checked by, calculating azimuths from known lines (AB and EF in, the above figure), , Construction: Draughtsman Civil - (NSQF Level -5 ): Related Theory for Exercise 2.5.77, , Copyright Free under CC BY Licence, , 139

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Traverse, Objectives: At the end of this lesson you shall be able to, • state uses of traverse surveying, • state types of traverse, • differentiate open and closed traverse., Traverse, Thorough knowledge of traverse surveying is required, for surveying using theodolite. In subsequent lesson,, traverse and theodolite traverse will be explained., A traverse is a series of connected lines whose lengths, and directions are known., The lengths of the lines are determined either, •, , by direct measurement, or by EDM equipment, or, , •, , by indirect measurement (tacheometry)., , Then angles are measured with, •, , Theodolite, or, , •, , Magnetic compass, , There is no opportunity for checking the accuracy of the, ongoing work in open traverse. So all survey, measurements are carefully repeated at the time of the, work. The major disadvantages of open traverse are,, 1 There is no check on summation of angles., 2 There is no check on positions of intermediate points., Steps to minimize errors in open traverse are,, , When the extent of survey is not large and desired, accuracy is not high, angles are not measured but, directions of lines are fixed by chain angles., Use of traverse surveying, , 1 Each distance should be measured twice in both, directions and also should be roughly checked by, tacheometry method., 2 Angles should be measured by method of repetition, and also should be checked by magnetic bearings., , •, , To establish the positions of boundary lines., , •, , To determine the positions of existing boundary lines., , •, , To calculate area within a boundary., , •, , To establish ground controls for photogrammetric, work., , •, , To establish ground controls for calculating earth work, quantities., , Distances are measured usually by tape or EDM, equipment and usually deflection angles are measured, at the traverse stations., , •, , To establish control for locating highways, railways, and other construction works., , Closed Traverse, , •, , To establish control for mapping., , Types of traverse, Two general classes of traverse are:, •, , Open traverse., , •, , Closed traverse., , An open traverse is usually run for establishing control, in preliminary surveys and construction surveys such as, roads, pipelines, etc. because the results are always open, to doubt., , Closed traverse (figure 2 (a) and (b) is that type of, traverse in which origin point and terminate point are, known locations, In such traverse, sum of all internal, angles should be equal to (2n-4) times right angles where, n is the number of sides., This mathematical condition provides computational, checks which gives indication of the accuracy of, measurements., , Open traverse, Open traverse (fig.1) is that type of traverse in which, origin point starts at known location and terminate point, ends at unknown location., , Closed traverse provides check for both linear and, angular measurements and therefore preferred to all, other types of traverse., Figure 2 (a) shows a closed traverse ABCDEA. The, traverse originates and terminates at the same point., , 140, , Construction: Draughtsman Civil - (NSQF Level -5): Related Theory for Exercise 2.5.77, , Copyright Free under CC BY Licence

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From the figure it is clear that this traverse is, mathematically and geometrically closed. It is caalled, closed-loop traverse., Figure 2 (b) shows a closed traverse ABCDEF. The, traverse originates and terminates at different points., From the figure it is clear that this traverse is, mathematically closd and geometrically open., , Traverse checking, Objectives: At the end of this lesson you shall be able to, • explain checks for open traverse, • explain checks for closed traverse., , Check in closed and open traverses, , Checks for angular measurements (Fig 2), , Open Traverse, Check on angular measurements (Fig 1), , No direct check of angular measurements is available., However some indirect check can be applied. Checking, bearings of cut-off lines is one of the indirect checking, methods and it is field checking method. Cut-off lines, are lines which are intervisible in a frame work of a, traverse., In the figure, line AE is known as cut-off line. Fore bearing, of the line AE is observed from A and its back bearing is, observed from E. In the bearing differs by 180°, the, work upto station E is taken as correct. If a small, discrepancy is found, it can be adjusted or if discrepancy, is large, the work should be repeated., , Another way of checking the work in open traverses is, to check the work at the time of plotting. Take many, bearing and angles to any prominent object or point from, as many portions as possible. At the time of plotting the, traverse, lines of sight to prominent object or point should, pass through same point. As given in the figure, line AM,, CM, DM, EM and FM should pass through the common, points, M., Check on linear measurements, The checking of linear measurements consists in, measuring each traverse line a second time, preferably, in the reverse direction on different dates and by different, parties., Closed traverse, Check on angular measurements, , Construction: Draughtsman Civil - (NSQF Level -5): Related Theory for Exercise 2.5.77, , Copyright Free under CC BY Licence, , 141

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Included Angles, , Bearing, , The sum of all included or interior angles in a closed, traverse is compared to the theoretical sum, given by, the equation (2n-4) x 90°., , In a traverse run by bearings of initial is determined after, completing the loop. Then it is compared with the initial, bearing taken at the starting of the traverse alternatly., The Fore Bearing of the last line measured at the last, statrion is compared with it back bearing measured at, the starting station., , If the error is within the permissible limits, it is adjusted., If it is large, the whole work should be repeated., The permissible closing error can be computed from the, formula., E=K, , , where K is the least count of the instrument, , and n is the number of sides of the traverse., Deflection Angles, The algebraic sum of the deflection angles should be, equal to 360°, taking the right deflection angle as positive, and left deflection angle as negative. This rule applies to, a loop traverse if the traverse does not cross one another., , Check on linear measurements, The checking of linear measurements consists in, measuring each traverse line a second time, preferably, in the reverse direction on different dates and by different, parties., In a closed traverse algebraic sum of latitudes as well, as departure is zero,i.e. sum of northing’s should be equal, to sum of southing’s and sum of easting’s should be, equal to sum of westings., , Classification of traverse, Objectives: At the end of this lesson you shall be able to, • classify traverse based on the instruments used, • explain method of traversing, • explain how to measure traverse length in theodolite traversing, • explain how to measure traverse angle in theodolite traversing., Classification of traverse based upon the, instruments used, , Compass traversing, , Classification of traverse based upon the instruments, employed are:, , When a compass is used to fix directions, the traverse, is called compass traversing. Method is already explained, in compass surveying module., , •, , Chain traversing, , Plane table traversing, , •, , Compass traversing., , •, , Plane table traversing, , •, , Theodolite traversing., , Traversing using plane table is called plane table, traversing. Method is already explained in plane table, surveying module., Theodolite Traversing, , Methods of traversing, A traverse can be run by several methods depending, upon the instrument. The classification of traverse based, upon the instruments employed and the method of, running the traverse and explained below., , Measurement of theodolite traverse lengths, Depending on accuracy required, the length can be, measured by:, , Chain Traversing, In this method, the entire work is done with a chain or, tape and no angle measuring instrument is employed., The directions of lines are fixed by linear measurements, only. Directions of lines are fixed by taking chain angles., Chain angles are generally liable to errors as the accuracy, of measurement of the angles, is proportional to the, accuracy achieved in measuring the tie distances., 142, , In the method of traverse, theodolite is commonly used, for providing horizontal control systems., , •, , Chaining., , •, , Taping., , •, , Tacheometry or,, , •, , EDM equipment., , For greater accuracy, lengths are measured in both, directions and average value is taken., , Construction: Draughtsman Civil - (NSQF Level -5): Related Theory for Exercise 2.5.77, , Copyright Free under CC BY Licence

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Measurement of theodolite traverse angles, Traverse angles can be:, •, , Interior angles,, , •, , Deflection angles,, , •, , Direct angles,, , •, , Azimuth angles or, , •, , Magnetic bearings., , Theodolite traversing methods - I, Objectives: At the end of this lesson you shall be able to, • state methods of theodolite traversing, • explain loose needle method, • explain fast needle methods, • compare loose needle and fast needle methods., Theodolite Traversing, , Direct method with transiting, , Any one of the following methods may be used for fixing, direction in theodolite traversing:, , In this method, instrument is set up at the starting station, A and the rearing is set to zero. By releasing the magnetic, needle, the telescope is brought in magnetic meridian, using lower plate clamp. Unclamp the upper plate and, the telescope is directed towards B and the reading is, taken. It is bearing of the line AB., , •, , Loosing needle method., , •, , Fast needle method, , •, , Included angle method., , •, , Direct angle method., , Instrument is shifted to B with both the clamp in tightened, , •, , Deflection angle method., , •, , Azimuth method., , position. Set up the instrument at B. Unclamp lower, clamp, direct the telescope to A. Plunge the telescope., Now, the telescope is in the line of sight of AB. Releasing, upper clamp, telescope is directed towards C. Now,, reading is the bearing of the line BC., , Loose needle method, In this method, a theodolite fitted with a magnetic, compass is used to determine the bearings of the lines., From bearings included angles are determined and, checked for theoretical sum of interior angles. If any error, is found , correction is distributed equally among the, angles and corrected bearings are completed. Loose, needle method is rarely used as it is prone to local, attraction., Fast needle method, In this method, the magnetic bearing of only the first line, is measured. The magnetic bearing of all other lines are, determined indirectly. This method is more accurate than, the loose needle method and is generally preferred, because only single magnetic bearing is measured., There are three methods of traversing by fast needle, method:, •, , Direct method with transiting, , •, , Direct method without transiting., , •, , Back bearing method., , Shift the instrument to the next station and repeat the, above steps at each station and measure the bearing of, the line., Direct method without transiting, Follow the steps described in the first paragraph of the, direct method with transiting. Shift the instrument to B., Now, without plunging the telescope, direct the telescope, to sight C and measured the reading. To obtain the, magnetic bearing a correction has to be applied to the, readings. Add 180º 00’00" if the reading measured is, less 180º 00’00" and subtract 180º 00’00" if the measured, reading is more than 180º 00’00"., Back bearing method, Follow the steps described in the first paragraph of the, direct method with transiting. Shift the instrument to, station B. Sight the station A as in the direct method with, transiting. Calculate the backbearing of the AB from the, forebearing measured. Set the vernier to the backbearing, of AB. Tighten the upper clamp. Using lower clamp, bisect A. Release upper clamp, rotate telescope in, clockwise direction and bisect C. Now, the reading is, forebearing of BC. The above process is repeated at, each station of the traverse to obtain the bearings of the, lines., , Construction: Draughtsman Civil - (NSQF Level -5): Related Theory for Exercise 2.5.77, , Copyright Free under CC BY Licence, , 143

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Direct method with transiting is quite easy method but, direct method without transiting gives the best results, even when the instrument is not in perfect adjustment., Back bearing method is seldom used., , Theodolite traversing methods - II, Objectives: At the end of this lesson you shall be able to, • explain included angle method, • explain direct angle method, • explain deflection angle method, • explain azimuth method., Included angle method, This method is suitable for closed traverse. In this, method magnetic bearing of first line only is taken. At, first station, say A, instrument is set up and levelled. If, instrument is fitted with magnetic compass, take fore, bearing of the line AB. If instrument is not fitted with, magnetic compass, take a fore bearing using prismatic, compass and record it. Set vernier A zero and bisect the, last station, say E. Tighten lower clamp and loose upper, clamp; turn the telescope in clockwise direction to sight, the station B. Bisect it accurately and measure the, included angle at A. All interior angles are measured, twice, one by face left and another by face right. To, measure angle more accurately, measure the angle by, repetition method. Measure the length of the closed loop, and record it., , This method may be used for open traverse or closed, traverse. In this method magnetic bering of first line only, is taken. At first station, Say A, instrument is set up and, leveled. If instrument is fitted with magnetic compass,, take fore bearing of the line AB. If instrument is not fitted, with magnetic compass, take fore bearing using prismatic, compass and record it. Shift instrument to the next, station, say B. Set vernier A zero and bisect the previous, station, A tighten lower clamp and loosen upper clamp,, turn the telescope in clockwise direction to sight the, station C. Bisect it accurately and measure the direct, angle. Accuracy can be improved by taking repeated, readings., Rotation of telescope for measuring direct angle at each, station should be clockwise., Deflection angle method (Fig 2), , Check the measured angles to theoretical sum of the, interior angles. If small error is found, distribute the error, equally and if error is large, repeat the work., Angles measured are interior angles if traverse is run in, anticlockwise direction and theoretical sum is equal to, (2n -4) x 90º, Angle measured are exterior angles if traverse is run in, clockwise direction and theoretical sum is equal to (2n+4), x 90º., Included angle method (Fig 1), , Direct angle method, (Refer the lesson deflection angle, direct angle and its, measurement)., 144, , (Refer the lesson deflection angle, direct angle and its, measurement.), This method is suitable for open traverse where only a, few details are located as the traverse is run. In this, method, magnetic bearing of first line is taken. At first, station, say A, instrument is set up and levelled. If, instrument is fitted with magnetic compass, take fore, bearing of the line AB. If instrument is not fitted with, magnetic compass, take a fore bearing using prismatic, compass and record it. Shift instrument to the next, station say B. Set vernier A zero and bisect the previous, station, A tighten lower clamp, transit the telescope and, loosening the upper clamp, turn the telescope either left, or right to sight the next station C. Record the angle, with deflection direction. Similarly measure deflection, angles at the traverse stations., , Construction: Draughtsman Civil - (NSQF Level -5): Related Theory for Exercise 2.5.77, , Copyright Free under CC BY Licence

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Magnetic bearings are also observed from each traverse, station. The angular closure is checked by calculating, bearing from known line bearing., Azimuth Method (Fig 3), , The angle between a line and the meridian measured in, clockwise direction, usually from the north of the meridian, is called azimuth of the line. Azimuths may be true,, magnetic or assumed, depending upon the reference, meridian adopted. Azimuth and bearing are similar and, azimuth is mostly used in geodetic and astronomical, surveying, whereas the term bearing is commonly used, in plane table surveying., In this method, at each traverse station, the back azimuth, of the preceding line and the azimuth of the forward line, are measured using a transit. This method is used, extensively for topographic and other surveys. Mehtod, is illustrated in the following figure., , Theodolite traversing phases, Objectives: At the end of this lesson you shall be able to, • explain theodolite traversing phases., Traverse Phases, , Marking of Stations, , •, , Reconnaissance, , •, , Selection of traverse stations, , •, , Marking of stations, , After finalizing the locations of the traverse stations, their, positions are marked on the ground. The station mark, should be permanent in nature as far as possible so that, the stations can be used in future if required., , •, , Measuring linear and angular measurements., , •, , Locating details, , •, , Plotting and adjusting closing error., , Measuring linear and angular measurements, Already discussed, Locating details, , Reconnaissance, Preliminary field inspection of the entire area to be, surveyed is known as reconnaissance., Selection of Stations, As far as possible the survey work should be based upon, the basic principle of surveying, number of station should, be minimum, stations should be intervisible, stations, should be selected on firm and level ground etc., , As per field conditions, adopting any of the methods of, principle of surveying, locate details. The angles and, distances should preferably be measured from the, traverse stations to avoid the errors in measurement of, distances along the traverse lines., Plotting and adjusting closing error, The method of plotting a traverse is already explained, on the previous module. Closing error will be dealt in, the next lesson., , Construction: Draughtsman Civil - (NSQF Level -5): Related Theory for Exercise 2.5.77, , Copyright Free under CC BY Licence, , 145

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Closing error, Objectives: At the end of this lesson you shall be able to, • explain theodolite traversing phases., • find magnitude and direction of closing error., , ∑L, , Closing Error, Sometimes a geometrically closed traverse fails to close, when there is closing error., Closing error is the distance by which the end of a, traverse falls short in coinciding with the starting point of, the traverse., As explained earlier, if a closed traverse work is correct,, the algebraic sum of the latitudes should be equal to, zero, and the algebraic sum of the departures should be, equal to zero, i.e. ∑L=0 and ∑D=0., Following figures shows a closed traverse ABCDA, in, which starting point and end point not coinciding., Close error of a closed traverse (Fig 1), , = (ByCy+CyDy) - (AyBy+DyA’y), = A’yAy., , Let A’x Ax is Ox and A’y Ay is Oy, then from the right, angled triangle, AA’Z, AA’, , = Closing error, , e, , = (Ox) 2 + (Oy) 2, 2, 2, ∑ L +∑ D, , The direction of the closing error is determined from then, tan θ, = opposite side adjacent side, = ∑D/∑L, The sign of and thus define the quadrant in which the, closing error lies., Sometimes the term relative error of closure is also used, to express precision of the survey, Relative error of Closure= (Closure Error) ÷ (Perimeter, of the traverse), Enlarged view of closing error (Fig 2), , The Distance A’A is the closing error., From the figures it is understood that horizontal, component and vertical component of A’A is A’ x Ax and, A’y Ay respectively., Algebraic sum of the horizontal components of the, lengths of the sides,, , ∑D, , = AxBx+BxCx – CxDx-DxA’x, = A’xAx., , Algeraic sum of the horizontal components of the lengths, of the sides, , 146, , Construction: Draughtsman Civil - (NSQF): Related Theory for Exercise 2.5.77, , Copyright Free under CC BY Licence

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Latitudes and departures, Objectives: At the end of this lesson you shall be able to, • determine latitudes, • determine departures, • balance the traverse using transit method, • balance the traverse using Bowditch’s (mathematical) method., Latitudes and departure (Fig 1 &2), , The departure of a line is its projection onto the eastwest meridian., The distance measured towards the east (right ward) is, called easting whereas the distance measured towards, the west (leftward) is called westing., From the reduced bearing or WCB and lengths of the, lines, the latitudes and departures of the lines can be, calculated., Latitude of OA is nothing =, , Ia CosØ1 (+), , Departure of OA is Westing = Ia SinØ1 (-), Latitude of OB is northing, , = Ib CosØ2 (+), , Departure of OA is easting = Ib SinØ2 (+), Latitude of OC is northing, , = Ic CosØ3 (-), , Departure of OC is easting = Ic SinØ3 (+), Latitude of OD is southing = Id CosØ3 (-), Departure of OD is westing =Id SinØ3 (-), Here is ‘l’ the length of the line and Ø the reduced bearing, of the respective line., Find coordinates of a line AB observed radially from a, station. A using magnetic compass, whose W.C.B are, <45° 00’00" <135° 00’00", < 225° 00’000’ and < 315°, 00’000’., Solution, , The latitude of a line is its projection onto the north-south, meridian., The distance measured towards the north (upward) is, called northing whereas the distance measured towards, the south (downward) is called southing., , Construction: Draughtsman Civil - (NSQF Level - 5): Related Theory for Exercise 2.5.77, , Copyright Free under CC BY Licence, , 147

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Line, , Length (m), , W.C.B., 45°00'00", , R.B., , Coordinates, , N45°00'00"E, , Latitude = 100 x cos 45°00'00" = +70.71 m, Departure = 100 x sin 45°00'00" = + 70.71 m, , 135°00'00", , S45°00'00"E, , Latitude = 100 x cos 45°00'00" = -70.71 m, Departure = 100 x sin 45°00'00" = + 70.71 m, , AB, , 100, , 225°00'00", , S45°00'00"W, , Latitude = 100 x cos 45°00'00" = -70.71 m, Departure = 100 x sin 45°00'00" = - 70.71 m, , 315°00'00", , N45°00'00"W, , Latitude = 100 x cos 45°00'00" = +70.71 m, Departure = 100 x sin 45°00'00" = - 70.71 m, , Line, , Length(m), , W.C.B, , R.B, , Coordinates (m), Latitude, , AB, , 100, , Departure, , Northing, , Southing, , Easting, , Westing, , +, , -, , +, , -, , 45°00'00", , N45°00'00E", , 70.71, , 70.71, , 135°00'00", , S45°00'00"E, , 70.71, , 225°00'00", , S45°00'00"W, , 70.71, , 315°00'00", , N45°00'00"W, , 70.71, , 70.71, , 70.71, 70.71, , Balancing the traverse, Objectives: At the end of this lesson you shall be able to, • explain balancing the traverse, • describe various mathematical and graphical methods of balancing the traverse., Balancing the traverse, , Mathematical methods, , The term balancing is generally applied to the operation, of applying corrections to latitudes and departures to, satisfy the conditions, ΣD =0, ΣL =0 for a closed traverse., , Bowdithch's or compass rule method, , For a traverse work we can have the following three, conditions:, 1 Angular accuracy is higher than the linear accuracy., E.g. A hilly terrain., 2 Angular accuracy is lower than the linear accuracy., E.g Angles measured with compass and distances, with an EDM equipment., 3 Angular accuracy is same as the linear accuracy. E.g., Angles measured with theodolite and linear distances, measured with an EDM equipment., Depending upon the above conditions traverse is, balanced. Traverse balancing can be done both, mathematically and graphically. There are many, methods for balancing traverse, but commonly used, mathematical methods and graphical methods are,, 148, , •, , Transit rule method, , •, , Graphical methods, , •, , Axis method, , Bowditch's method, This method was suggested by C.F Bowditch. He made, some assumptions for developing this method., According to this method the errors in linear, measurement are proportional to and that the errors is, angular measurements are inversely proportional to ,, where 'I' is the length of the line., Correction to latitude = Total error in latitude, x (Length of that traverse line) ÷ (total length, of traverse), , Construction: Draughtsman Civil - (NSQF Level - 5): Related Theory for Exercise 2.5.77, , Copyright Free under CC BY Licence

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Correction to departure = Total error in, departure x (length of that traverse line) ÷ (total, length of traverse), , Line, , Length(m), , Included angle, , W.C.B, , AB, , 250, , <A=95°00’00”, , 140°00’00’’, , The sign of the above corrections depends, upon the algebraic sum of latitudes and, departures., , BC, , 650, , <B = 75°00’00”, , -, , CD, , 120, , <C = 125°00’00”, , -, , DA, , 700, , <D = 70°00’00”, , ΣS, the sign of corrections for northings, If ΣN>Σ, is negative and for southings positive and vice, versa., ΣW, the sign of corrections for eastings, If ΣE>Σ, is negative and for westings positive and vice, versa., Bowdith’s rule is also known as compass rule because, this method is most suitable for compass survey. However, this method is most commonly used for an average, engineering survey because it is easy to apply and the, corrections do not alter the plotting., Transit rule method, When the angular measurements are more precise than, the linear measurements, balancing the traverse is done, by employing transit rule. According to this rule, the total, error in latitude and departure is distributed in proportion, to the latitude and departure of the traverse line., Correction to latitude = Total error in latitude, x (Latitude of that traverse line ) ÷ (arithmetic, sum of latitudes), Correction to departure = Total error in, departure x (Departure of that traverse line) ÷, (arithmetic sum of departures), The sign of the above corrections depends, upon the algebraic sum of latitudes and, departures., ΣS, the sign of corrections for northings, If ΣN>Σ, is negative and for southings positive and vice, versa., ΣW, the sign of corrections for eastings, If ΣE>Σ, is negative and for westings positive and vice, versa., Plotting a traverse survey, After balancing the traverse, the traverse is plotted by, rectangular coordinates., , Solution, Sum of the observed included angles of the traverse, =250°00’00” + 75°00’00” + 125°00’00” + 70°00’00” =, 365°00’00”, Theoretical sum of the included angles = (2n-4) x 90° =, (2x4-4) x 90° = 360°00’00”., Error = 365°00’00” - 360°00’00” = +05°00’00”, Therefore a correction of - (05°00’00”/4) should be, applied to each angle, i.e -01°15’00” correction., Hence corrected included angles at each stations are, <A = 95°00’00” - 01°15’00” - 93°45’00”, <B = 75°00’00” - 01°15’00” - 73°45’00”, <C = 125°00’00” - 01°15’00” - 123°45’00”, <D = 70°00’00” - 01°15’00” - 68°45’00”, Calculation of Bearings, Bearing of BC =, Bearing of line AB + <B -180°00’00” = 140°00’00”, +73°45’00” -180°00’00” = 33°45’00”, Bearing of CD =, Bearing of line BC+<C -180°00’00” = 33°45’00”, +123°45’00” -180°00’00” = 337°30’00”, Bearing of DA =, Bearing of line CD+<D -180°00’00” = 337°30’00”, +68°45’00” -180°00’00” = 226°15’00”, Bearing of AB =, , Exercise, A first hand group of surveyors conducted a closed, traverse with a theodolite. The lengths and observations, of a closed traverse ABCDA are given below. Prepare a, Gale’s traverse table., , Construction: Draughtsman Civil - (NSQF Level - 5): Related Theory for Exercise 2.5.77, , Copyright Free under CC BY Licence, , 149

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R.B, , Reduced bearing of the closing error = tan-1(ΣD/ΣL), , 140°00’00”, , S40°00’00’’E, , = tan-1(29.7592/24.2495), , 650, , 33°45’00”, , N33°45’00”E, , CD, , 120, , 337°30’00”, , N22°30’00”W, , = 50°49’30” (SW quadrant, since ΣL and ΣD are, negative), , DA, , 700, , 226°15’00”, , S46°15’00”W, , Line, , Length(m), , AB, , 250, , BC, , W.C.B, , Bearing of line DA+<A -180°00’00” = 226°15’00”, +93°45’00” -180°00’00” = 140°00’00” (check), , Note : Practically this magnitude of error is impermissible, for most type of works. Here, as a sample question we, are preparing Gale’s table., Corrections, , Consecutive coordinates, , Latitude = 250 x Cos 40°00’00” = -191.5111 m, , As per transit method, correction to latitude (or departure), = Total error in latitude (or departure) x (Latitude (or, departure) of that traverse line ) ÷(arithmetic sum of, latitudes (departures), , Depature =250 x Sin 40°00’00” = +160.6969 m, , Line AB, , Coordinates of B, , Coordinates of C, Latitude = 650 x Cos 33°45’00” = +540.4552 m, Depature =250 x Sin 33°45’00” = +361.1206 m, Coordinates of D, , Corrections to southing = 24.2495 x (191.5111/1326.891), = -3.4999 m (ΣS<ΣN, the sign of corrections for southings, is negative and for northings positive), Corrections to easting = 29.7592 x (160.6969/1073.394), = +4.4552 m (ΣW>ΣE, the sign of corrections for westings, is negative and for eastings positive), , Latitude = 120 x Cos 22°30’00” = +110.8655 m, , Line BC, , Depature =120 x Sin 22°30’00” = -45.9220 m, , Correction to northing = 24.2495 x (540.4552/1326.891), = +9.8770m, , Coordinates of A, Latitude = 700 x Cos 46°15’00” = -484.0591 m, , Correction to easting = 29.7592 x (160.6969/1073.394), = +10.0118 m, , Depature =700 x Sin 46°15’00” = -505.6547 m, , Line CD, , 191.5111, 540.4552, , 361.12.06, , 110.8655, , 521.8175, , 651.3207, , Correction to northing = 24.2495 x (110.8655/1326.891), = +9.8770m, , 160.6969, , 484.0591, , 45.922, , Correction to westing = 29.7592 x (45.9220/1073.394) =, +, 1.2731 m, , 505.6547, , 24.2495, , 29.7592, , Since, ΣL = -191.5111+540.4552+110.8655- 484.0591, = -24.2495 m, ΣD = +160.6969+361.1206 - 45.9220 - 505.6547 = 29.7592 m, , Line DA, Correction to southing = 24.2495 x (484.0591/1326.891), = +8.8463 m, Correction to westing = 29.7592 x (505.6547/1073.394), = +14.0189 m, Corrected consecutive Coordinates, , Hence there is closing error,, Closing error, e =, , =, , (∑ L )+ (∑ D ), 2, , 2, , (− 24.2495 )2 + (− 29.7592 ), , AB, 191.5111 - 3.4999 = 188.0111 m, 160.6969+4.4552 = 165.1521 m, BC, , = 38.4168 m, 150, , Construction: Draughtsman Civil - (NSQF Level - 5): Related Theory for Exercise 2.5.77, , Copyright Free under CC BY Licence

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540.4552 + 9.8770 = 550.3322 m, , Departure =500.0000 +165.1521 = 665.1521 m (easting, is positive so additition), , 361.1206 + 10.0118 = 371.1324 m, Coordinates of C, CD, Latitude =311.9889 + 550.3322 = 862.3211 m, 110.8566 + 2.0261 = 112.8916 m, Departure = 665.1521 + 371.1324 = 1036.2845 m, 45.9220 - 1.2731 =44.6488 m, Coordinates of D, DA, Latitude = 862.3211+112.8916 = 975.2127 m, 484.0591 - 8.8463 = 475.2127 m, Departure = 1036.2845 - 44.6488 = 991.6357 m, 505.6547 - 14.0189 = 491.6357 m, Coordinates of A (check), Independent Coordinates, Latitude = 975.2127 - 475.2127 = 500.0000 m, Assuming coordinates of station A as 500,500 (latitude,, departure),, , Departure = 991.6357 - 491.6357 = 500.000 m, , Coordinates of B, Latitude = 500.00000 - 188.0111 = 311.9889 m (southing, is negative so subtraction), , Gale’s table. Traverse balanced using transit method, , Construction: Draughtsman Civil - (NSQF Level - 5): Related Theory for Exercise 2.5.77, , Copyright Free under CC BY Licence, , 151

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152, , Construction: Draughtsman Civil - (NSQF Level -5): Related Theory for Exercise 2.5.77, , Copyright Free under CC BY Licence, , Consecutive, , Correction (m), , Corrected, consecutive, coordinates (m), , Departure E, , A, , Instrument at, , 95°00'00", , Angle, , B, , -1°15'00", , Correction, , Sight to, , 93°45'00", , 140°00'00", , W.C.B, , Corrected angle, , S40°00'00", , R.B, , SE, , Quadrant, , 191.5111, , 160.6969, , -3.4999, , 250, , Northing (+), , Southing (-), , Easting (+), , Westing (-), , Northing, , Southing, , B, , C, , 75°00'00", , -1°15'00", , 73°45'00", , 33°45'00", , N33°45'00"E, , NE, , 650, , 540.4552, , 361.1206, , +9.8770, , +10.0118, , +4.4552, , Easting, , 112.8916, -1.2731, , 550.3322, , Northing (+), , 371.1324, , 862.3211, , Westing, , 188.0111, , Southing (-), , 165.1521, , 311.9889, , Length (m), , Latitude, , Departure E, Coordinates (m), , Latitude, , Departure E, , Latitude, , Easting (+), , Westing (-), , Northing (+), , 1036.2845, , C, , D, , 125°00'00", , -1°15'00", , 123°45'00", , 337°30'00", , N22°30'00", , NW, , 120, , 110.8655, , 45.922, , +2.0261, , -14.0189, , 44.6488, , 975.2127, , 99.6357, , SW, , 484.0591, , 505.6547, , -8.8463, , 663.2238, , 475.2127, , 491.6357, , 500, , 500, , D, , A, , 70°00'00'', , -1°15'00", , 68°45'00", , 226°15'00", , S46°15'00"W, , Easting (+), , Independent, Coordinates (m), , 665.1521, , Assuming coordinates of A (500.00, 500.00) As, maximum value for latitude is 475.2127 and departure is 491.6357, , Remarks, , Total, , 651.3207, , 675.5702, , 521.8175, , 551.5767, , 663.2238, , 536.2845, , 536.2845, , Algebraic sum, of latitude or, departure, , -24.2945, , -29.7592, , 0.00, , 0.00

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Corrections, , BC, , As per Bowditch’s arithmetical method, correction to latitude = Total error in latitude (or departure) x (length of, that traverse line) ÷ (total length of traverse), , 540.4552+9.1640, , = 549.6192 m, , 361.1206 + 11.2462, , = 372.3668 m, , Line AB, , CD, , Corrections to southing = 24.2495 x (250/1720) =, 3.5246m (ΣS>ΣN, the sign of corrections for southings, in negative and for northings positive), , 110.8655 + 1.6918, , = 112.5573 m, , 45.9220 - 2.0762, , = 43.8457m, , Corrections to easting = 29.7592 x (250/1720), =+4.3254m (ΣW>ΣE, the sign of corrections for westing, is negative and for eastings positive), , DA, 484.0591 - 9.8669, , = 474.1901 m, , Line BC, , 505.6547 - 12.1113, , = 493.5434 m, , Correction to northing = 24.2495 x (650/1720) = +1.6918m, , Independent Coordinates, , +, , Corrections to easting = 29.7592 x (650/1720) =, 11.2462m, , Assuming coordinates of station A as 500,500 (latitude,, departure), coordinate of B., , Line CD, , Latitude = 500.0000 - 187.9864 = 9864 = 312.0136 m, , Correction to northing, , = 24.2495 x (120/1720), = + 9.1640m, , Correction to westing, , = 29.7592 x (120/1720), = − 2.0762 m, , Departure = 500.0000 +165.0223 = 665.0223 m, Coordinate of C, Latitude = 312.0136 + 549.6192 = 861.6328 m, , Line DA, , Departure = 665.0223 + 372.3668 = 1037.5189 m, , Correction to southing = 24.2495 x (700/1720), = − 9.8689 m, , Coordinate of D, , Corrections to westing = 29.7592 x (700/1720), = − 12.1113m, , Departure = 1036.2845 − 43.8458 = 993.5434 m, , Corrected consecutive coordinates, , Latitude = 862.3211 + 112.5573 = 974.1901 m, , Coordinate of A (check), Latitude = 974.1901 − 474.1901 = 500.0000 m, , AB, 191.5111 − 3.5246, , = 187.9864 m, , 160.6969 + 4.3254, , = 165.0223 m, , Departure = 993.5434 − 493.5434 = 500.000 m, , Gale’s table. Traverse balanced using bowditch’s method, , Construction: Draughtsman Civil - (NSQF Level -5): Related Theory for Exercise 2.5.77, , Copyright Free under CC BY Licence, , 153

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154, , Construction: Draughtsman Civil - (NSQF Level -5): Related Theory for Exercise 2.5.77, , Copyright Free under CC BY Licence, , Consecutive, , Correction (m), , Corrected, consecutive, coordinates (m), , Departure E, , A, , Instrument at, , 95°00'00", , Angle, , B, , -1°15'00", , Correction, , Sight to, , 93°45'00", , 140°00'00", , W.C.B, , Corrected angle, , S40°00'00", , R.B, , SE, , Quadrant, , 191.5111, , 160.6969, , -3.5246, , 250, , Northing (+), , Southing (-), , Easting (+), , Westing (-), , Northing, , Southing, , B, , C, , 75°00'00", , -1°15'00", , 73°45'00", , 33°45'00", , N33°45'00"E, , NE, , 650, , 540.4552, , 361.1206, , +9.1640, , +11.2462, , Easting, , 549.6192, -1.6918, +4.3254, , 187.9864, , 372.3668, , 861.6328, , Westing, , Northing (+), , Southing (-), , 165.0223, , 312.0136, , Length (m), , Latitude, , Departure E, Coordinates (m), , Latitude, , Departure E, , Latitude, , Easting (+), , Westing (-), , Northing (+), , 1037.5189, , C, , D, , 125°00'00", , -1°15'00", , 123°45'00", , 337°30'00", , N22°30'00", , NW, , 120, , 110.8655, , 45.922, , +1.6918, , -12.1113, , 112.5773, , 43.8457, , 974.1901, , 993.5434, , SW, , 484.0591, , 505.6547, , -9.8689, , 474.1901, , 493.5434, , 500, , 500, , D, , A, , 70°00'00'', , -1°15'00", , 68°45'00", , 226°15'00", , S46°15'00"W, , Easting (+), , Independent, Coordinates (m), , 665.0223, , Assuming coordinates of A (500.00, 500.00) As, maximum value for latitude is 475.2127 and departure is 491.6357, , Remarks, , Total, , 651.3207, , 675.5702, , 521.8175, , 551.5767, , 662.1765, , 537.3891, , 537.3891, , Algebraic sum, of latitude or, departure, , -24.2945, , -29.7592, , 0.00, , 0.00

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Construction, Draughtsman Civil - Carpentry joints, , Related Theory for Exercise 2.6.78, , Carpentary joints - I, Objectives: At the end of this lesson you shall be able to, • define the term carpentry and joinery, • state the different technical terms in carpentry, • state the principle of joints, • enumerate classification of joints, • explain the types of lenthening joint., Introduction, , Planing, , Now a days wood is a valuable building material, which, is not easily available everywhere, so one has to learn, with more care about carpentry joints and fasteners and, fixtures. By the study of these a trainee can select a, right joint for a right position and to make that joint in the, right way., , It is the process of taking off the shaving from wood,, with the help of a tool known as planer. By planing, timber, surfaces are made smooth., Mitring and scribing, Mitring is the process of joining two wooden members, at a angle, if one end of moulding is cut to suite the profile, of another moulding it is known as scribing., , Definition, The timber which is to be used for the structural purpose, (such as doors, windows, frames, trusses etc) is to be, dressed plained framed and placed in position. Thus a, carpenter constructs permanent timber work such as, roofs, floors etc. as well as temporary timber work such, as scaffolding, shoring , centering etc., , Moulding, It is the process of shaping various units of construction, either by hand or by machine., Rebating, , The term joinery is used to indicate the art of preparing, internal fittings and finishing of timber. Thus a joint, construct timber works such as door, windows, stairs, floorboard, furniture, cup-boards etc. Thus the joinery is, used for delicate construction required precise, workmanship for enhancing the architectural beauty of, timber. In India the workman who is employed for the, work of carpentary and joinery is known as carpenter., Technical Terms in Carpentary, The following technical terms are commonly used in, carpentry., Sawing, , It is the process of cutting a rectangular groove on the, edge of a timber piece so as to enable the edge or tongue, of another timer piece to fit into the former., Housing, It is the process of sinking of edge of one piece of timber, into another by cutting grooves across it grain., Groove and grooving, Grooving is a term used to indicate a recess formed in a, timber member. If the groove is made parallel to the, grain, it is known as plough grooving. If the groove is, made across the grains, it is known as cross grooving., , It is the art of cutting wood by means of a saw., Nosing, Shooting, It is the art of dressing of edges of timber pieces as to, make them straight and square with the face., , Nosing is the edge of portion overhanging a vertical, surface., Studding, , Chamferring, It consists, of taking off the edge or corner of a wooden, member. The Chamfered member has a slopping edge, which is usually has a slope of 450. If the angle of chamfer, is other than 450 then it is known as a bevel., , It is the term applied to the fixing of small timber battens, to timber walls to which laths and boards are to be nailed., , 155, , Copyright Free under CC BY Licence

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Battens, , Lengthening Joint, , It is a narrow strip of wood which is nailed over joints of, boards., , These joints are also known as longitudinal joints or, spliced joints. These joints are used to increase the, length of wooden member. The method of lengthening, depends upon the situation of a member in a framed, structure. Lengthening joints are of various types., , Veneering, It is the process of covering of entire or part of exposed, surface of timber by means of veneers for decorative, purpose., , 1 Lapped joint, , Bead, , 3 Scarfied joint, , It is the rounded or semicircular moulding provided on, the edge or surface of wood., , 2 Fished joint, , 4 Tabled joints, Lapped joint (Fig 1 & 2), , Principles covering the construction of joint, The joints play the most important role in timber, construction because they improve aesthetic, appearance, provide structural stability and facilitate the, construction. However they form the weakest part of a, timber structure. Hence the following general principle, baed on the recommendations of Proff: Rankine, should, be observed in the construction of timber joints., The Joint should be cut and placed in such a way that it, weakens the connection member to the minimum., Each abutting surface of a joint should be as far as, possible, normal to the line of pressure coming upon the, joints., Each abutting surface of a joint should be designed for, the maximum compressive stress likely to come upon it., The surface of a joint should be formed and fitted, accurately so that there is even distribution of pressure., The fastenings, used to connect members may be so, proportional that they possess equal strength in relation, to the member which they connect., , Classification of Joints, , This is the simplest form of joint and is formed by putting, two timber pieces one over the other for a short distance, and then binding them together by means of iron straps, or stirrups, iron straps are provided with bolts on sides, for additional strength if the member has to resist a tensile, stress, the bolts passing through both the pieces may, be provided., , Joints are classified into the following six categories., , Fished Joint (Fig 3), , The fastening should be placed and designed so as to, avoid failure of a joint by shear or crushing., The joint should be simple as far as possible., , i, , Lengthening joints., , ii Widening joints, iii Angle joints, iv Oblique – shouldered joint, v Bearing joint, vi Framed joint., , 156, , Construction: Draughtsman Civil - (NSQF Level - 5): Related Theory for Exercise 2.6.78, , Copyright Free under CC BY Licence

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In this joint the end of the two members are cut square, and placed touching each other. They are then jointed, together placing wooden or iron fish plate on opposite, faces and securing these by passing boths through them., The bolts are arranged in zig-zag fashion in plan. So, that there is only one bolt hole at any cross-section. The, ends of fish plate should be slightly bent and pressed, into the timber pieces, to increase the strength of joints., Keys and intended fish plates are also provided to the, strengthening the joints. It is used for rough and, temporary structure such as scaffolding, centering,, shoring and form work etc., Scarfied joint or spliced joint (Fig 4), , In this type of joint, the projections are made at the end, of one piece and corresponding depressions are formed, on the other piece. Two pieces are then secured together, by means of bolts, straps, fish plates and keys. Such, joints give good appearance, since the uniform depth of, the member is obtained., , b Rebated joints (Fig 7), It is formed by overlapping cut portions. The joint remains, dust proof after the shrinkage of timber., , Rebated and filleted joints (Fig 8), , Tabled joint (Fig 5), , It is formed by introducing wooden fillet in the rebated, portions, having small depression. It is used for floors of, factories etc., Ploughed and Tongued joint (Fig 9), , These joints are formed when the member is subjected, to both tension as well as compression. It is similar to, spliced joint but is formed by cutting special shape in, both pieces and securing then with fish plate, bolts, keys, etc., , It is formed by introducing wooden fillet in the grooves, cut in the two pieces., , ii Widening Joint, These joints are also called side joints or boarding joints, and are used for extending the width of boards or planks., The members are placed edge to edge. These are used, for wooden doors, floors, tables etc., a Butt joints (Fig 6), , Tongued and grooved joint (Fig 10), It is formed by making fillet in one piece and groove in, the other., , These are also known as square plain or ordinary joints, are it is used for ordinary purposes., Construction: Draughtsman Civil - (NSQF Level - 5): Related Theory for Exercise 2.6.78, , Copyright Free under CC BY Licence, , 157

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It is formed by making grooves in the centre portion at, the end of each piece and inserting dowels of gun metal, brass, bronze or copper. This joints is very strong., Matched and beaded joint (Fig 14), , Rebated, tongued and grooved joint (Fig 11), , This joint is formed by tongued and grooved arrangement, and has special moulding on one silde to give good, appearance., It is formed by forming a rebate in addition to tongue and, groove. Nail is placed in such a way that it cannot be, seen., , Matched and V- Jointed Joint (Fig 15), , Splayed Joint (Fig 12), , This is a similar to the beaded joint expect that it is, chamfered in shape of V., Dovetailed joint (Fig 16), It is formed by splaying the ends of the timber pieces., This joint is used for ordinary purpose but it is superior, to butt joint., Dowelled Joint (Fig 13), , It is formed by providing dovetail shaped keys to fit in, the corresponding grooves in the connecting members., , 158, , Construction: Draughtsman Civil - (NSQF Level -5): Related Theory for Exercise 2.6.78, , Copyright Free under CC BY Licence

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Carpentry joints - II, Objectives: At the end of this lesson you shall be able to, • explain the bearing joints, • explain the angled joint (cornoer joints), • explain different types of fastenings and their uses., Bearing joint, Bearing joints are provided when two members meet at, right angles to each other., Bearing joints are of the following types, 1 Halved Joint (Fig 1), , 4 Housed Joint (Fig 4), , These joints are formed by cutting through half the depth, of each member meeting at right angle, so that top, surfaces of both the members flush. Various forms of, halved joints are angle halved joint, longitudinal halved, joint, tee-halved joint, bevelled halved joint and dovetail, halved joint., 2 Notched Joint (Fig 2), , It is formed by fitting the entire thickness of the end of, one member for a short distance into another piece. It is, used in stairs in which the ends of risers and treads are, housed in the strings., 5 Chase – Mortise joint (Fig 5), , This joint is formed by cutting notch in one or both pieces., The former is known as single notched joint while the, latter is known as double notched joint., 3 Cogged joint (Fig 3), This joint is formed by cutting small notch in the upper, timber member and providing notches on the lower, member with a projection in the centre. The projection, is known as cog. The upper piece in which small notch, has been formed, accommodates this cog., , This is used for joining a subsidiary member to a primary, member already fixed earlier. A wedge shaped recess is, formed in the main member while a tenon of, corresponding shape is formed in the secondary, member., , Construction: Draughtsman Civil - (NSQF Level -5): Related Theory for Exercise 2.6.78, , Copyright Free under CC BY Licence, , 159

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6 Dove –tailed joint (Fig 6), , This joint is formed by cutting wedge shaped pieces from, each member and by hooking the projection of one, member into other. This joint is used for curves of skylights and corners of boxes, cabinets, drawers etc., 7 Mortise and tenon joint (Fig 7), , 10 Fox-tail Wedging joint (Fig 10), , This joint is formed by cutting projection known as tongue, or tenon in one member which fits into a slot called, mortise, cut into the other member., , This joint is formed by cutting a slightly dovetail shaped, mortice to have a lesser depth than the member. The, tenon is cut and two sockets are made in the tenon in, which wedges are inserted. The entire assembly is then, inserted in the mortice., , 8 Joggle or Stump or Stub tenon Joint (Fig 8), , 11 Tusk-tenon joint (Fig 11), , This is used for framing studs into the sill of wooden, partition all. It is similar to mortice tenon joint except, that the tenon is short in length and does not extend for, full depth of mortised member., , This joint is very strong and is commonly used to join, timber pieces for construction. The joint is formed of, tenon, tusk and horn. It is employed for joining members, of equal depth, meeting each other at right angle., , 9 Bridle Joint (Fig 9), , Angle Joint (Corner Joint), , This joint is commonly used in wooden trusses at the, junction of struts and ties. It is formed by cutting a type, of mortise at the end of one piece to fit in the bridle or, projection left upon another piece., , Corner Joints are used when two members are to be, jointed so as to form a corner or angular edge. These, joints are very often secured by nails and glue., , 160, , Construction: Draughtsman Civil - (NSQFLevel -5): Related Theory for Exercise 2.6.78, , Copyright Free under CC BY Licence

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The members are connected by joining them edge to, edge. The joints may be rebated and beaded to give, better appearance. The joints may also be tongued., 2 Grooved and tongued joint (Fig 13), , The joint is formed by fitting the projection of one member, into the groove of the other., 3 Plain Mitred Joint (Fig 14), , The joint is formed by cutting the edge of both the, members by an angle., 4 Mitred and feathered joint (Fig 15), , Following are the commonly used angle joints, 1 Butt joint (Fig 12), , In this an additional wooden member called feather is, inserted in the middle of the mitred joint., , Construction: Draughtsman Civil - (NSQF level -5): Related Theory for Exercise 2.6.78, , Copyright Free under CC BY Licence, , 161

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5 Housed Joint (Fig 16), , 9 Mitred, rebated and feathered joint (Fig 20), , The joint is formed by fitting one member completely, into the depression of the other., 6 Shouldered and house joint (Fig 17), , The joint is formed by inserting a feather in the mitred, and rebated joint., 10 Tongued Grooved and Mitred Joint (Fig 21), , In this joint only a part of one member is fit into the, corresponding depression of the other., 7 Dove tailed housed joint (Fig 18), This joint is formed by making tongue and groove in the, lower edge of the mitred, to give improved appearance., Oblique-shouldered Joint, These joints are used when two members meet at an, angle other than right angle, such as in timber truss, construction., Following are the different types of oblique joints, 1 Briddle Joint, This is a special type of housed joint in which one, member is housed into the other by dovetail shapped, projection and cut., , 2 Mitred Joint, 3 Dove-tailed halved joint, , 8 Mitred and rebated joint (Fig 19), The joint is formed by using rebate in addition to the, mitre., , 162, , These joints are similar to those discussed earlier except, that members will meet at an angle other than right angle, , Construction: Draughtsman Civil - (NSQF Level -5): Related Theory for Exercise 2.6.78, , Copyright Free under CC BY Licence

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4 Birds Mouth Joint (Fig 22), , 1 Wire-nails: These are circular or oval in shape made, of wrought iron or steel., 2 Cut-nails: These are trapezoidal in section, and are, smaller in length., 3 Floor boards: These are tapering nails of rectangular, section with head at one end and are used for, securing floor boards., 4 Pins: These are small wooden pieces used for, securing joints of door and window shutters., , This joint is formed by cutting angular notch called birds, mouth, in the main member to which the other member, is partially inserted and fitted., 5 Oblique – tenon Joint (Fig 23), , 5 Screws: They make the joint stronger because of, the greater holding power. These may be round, headed or counter sunk., 6 Coach Screw: It has a square head which is turned, by a spanner., 7 Bolts: These are used for large size members;, Washers are used with nuts to prevent damage to, timber., 8 Spikes: These are large nails of 10-15cm length, used to secure heavy members., , This is used for connecting horizontal member to an, inclined member, both the members being bigger in size., The tenon of an inclined member is oblique, which is, fixed into the corresponding mortise of the horizontal, member. The joint is further strengthened by bolt, key,, strap etc., Framing Joint, Framing joints are used to construct the frames of doors,, windows, ventilators etc. These joints are similar to, bearing joints except that they are not supposed to carry, stress as compared to bearing joints. To get the desired, architectural effects, these joints are suitably modified., Fastenings and Tools, The timber joints are secured in position with the help of, following fastenings. (Fig 24), , 9 Connectors: These are metal rings or corrugated, sheet pieces which are driven into the member after, abutting them., 10 Dog: A dog is a v-shaped wrought iron fastening with, pointed ends, which is driven to connect the members., It is used for temporary structures., 11 Dowels: These are small wooden pieces which are, driven in the members to keep their faces in one, plane., 12 Socket: These are made of wrought iron or cast iron, and are used to protect the end of the members., Sockets are called shoes when they are fixed to the, bottom end of the member., 13 Straps: These are bands of steel or wrought iron, which can be used to join two pieces of timber. The, breath of strp is about 40mm-50mm and thickness, depends upon the stress coming upon it., 14 Fish plate: These are wooden or iron plates which, are placed on the opposite faces of timber joint. The, fish plates are secured in position by bolt passing, through the timber pieces., 15 Wedger: These are tapering pieces of wood, used in, securing mortice and tenon joint., , Construction: Draughtsman Civil - (NSQF Level -5): Related Theory for Exercise 2.6.78, , Copyright Free under CC BY Licence, , 163

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Types of doors - I, Objectives: At the end of this lesson you shall be able to, • define doors & windows, • explain the features & location of doors & windows, • enlist the technical terms, • determine size of doors, • explain door frame, • enumerate types and classifications of doors, • explain types of doors according to arrangement of components Introduction., A door or window is an unavoidable part of building, which, may be a frame work of wood, steel, glass to give access, to men, materials, light and ventilation., , The frame is secured to the wall opening with the help of, hold fasts. And window shutters are held in position by, the window frame., , Definition, , Location of doors and windows, , Door may be defined as an openable barrier secured in, a wall opening. A door is provided to give an access to, the inside of a room of a building., , The following points should be kept in mind while locating, doors and windows., , Basically a door consists of two parts:, 1 Door frame and, 2 Door shutter., The door shutter is held in position by the door frame, which in turn is fixed in the opening of the wall by means, of hold fasts., A window is also a vented barrier secured in a wall, opening. The function of the window is to admit light and, air to the inside of building and to give a view to the, outside., A window also consists of two parts:, 1 Window Frame., 2 Window shutter., , 1 The number of doors in a room should be kept, minimum since large number of doors causes, obstruction and consume more area in circulation., 2 The location of door should meet functional, requirements of a room. It should not be located in, the centre of the length of a wall. A door should, preferably be located near the corner of a room, nearly, 20cm away from the corner., 3 If there are two doors in a room, then they should, preferably be located in opposite walls facing each, other, so as to provide good ventilation and free air, circulation in the room., 4 The size and number of windows should be decided, on the basis of important factors, such a distribution, of light control of ventilation and privacy of occupants., 5 The location of a window should also meet the, functional requirements of the room such as interior, decoration, arrangement of furniture etc., 6 A window should be located in opposite walls, facing, door or another window, so that cross ventilation is, achieved., 7 From the point of a view of fresh air, a window should, be located on the northern side of a room or located, in the prevalent direction of wind., 8 The Sill of a window should be located about 70cm80cm above floor level of the room., , 164, , Construction: Draughtsman Civil - (NSQF Level - 5): Related Theory for Exercise 2.6.78, , Copyright Free under CC BY Licence

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Technical terms, Sl No., , Terms, , 1, , Frame: It is an assembly of, horizontal and vertical members, forming an enclosure to which the, shutters are fixed., , 2, , Shutters: Openable part of a door, or window., , 3, , Head: Topmost horizontal part of a, frame., , 4, , Sill: Lowermost horizontal part of a, frame., , 5, , Horn: Horizontal projection of head, or sill., , 6, , Style: Vertical outside member of the, shutter frame., , 7, , Top rail: Top most horizontal, member of a shutter., , 8, , Lock rail: Middle horizontal member, of door a shutter., , 9, , Bottom rail: Lower most horizontal, member of a shutter., , 10, , Cross rail: Additional horizontal rails,, fixed between the top and bottom, rails of a shutter., , 11, , Panel: Area of shutter enclosed, between the adjacent rail and styles., , 12, , Mullion: Vertical member of a, frame, which is employed to subdivide a window or a door., , 13, , Transom: Horizontal member of a, frame which is employed to subdivide a window opening horizontally., , 14, , Hold fast: Mild steel flats, generally, bent into Z-shape, to fix or hold the, frame to the opening., , Figure, , Construction: Draughtsman Civil - (NSQF Level -5): Related Theory for Exercise 2.6.78, , Copyright Free under CC BY Licence, , 165

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Sl No., , Terms, , 15, , Rebate: Depression or recess made, inside the door frame, to receive the, door shutter., , 16, , Sash: Special type of frame, made, of light sections and designed to carry, glass., , 17, , Louvers: A piece of timber which is, fixed is in inclined position within a, frame., , 18, , Architrave: A strip of wood, usually, moulded or splayed which is fixed, around the sides and head of, opening, , Size of Doors, , Figure, , c 1.20m x 2.25m, , The size of door should be such that it would allow the, movement of largest object and tallest person likely to, use. As a rule, the height of door should not be less than, 1.80M. The width of door should be such that two, persons can pass through it walking shoulder to shoulder., The common widths – height relation used in india is as, follows., 1 Width = 0.40 to .0.60 height, , Indian standard Instituion recommends that the size of, door frame should be derived after allowing a margin of, 5mm all round an opening for convenience of fixing. The, width and height of an opening is in directed by no.of, modules where each modules is of 100mm., For example a designation of 8 DS 20 denotes a door, opening having width equal to 8 modules (is 8x 100=800, mm) and height=20 modules (is 20 x 100 = 2000 mm), with single shutter., , 2 Height= (width +1.2) metre., The following are the generally adopted sizes of doors, for various types of buildings., , The letter ‘D’ denotes a door opening and letter‘s’ stands, for single shutter. Illrly the designation 10DT 21 of door, opening denotes., , I, , Doors of residential building., , Width of opening = 10 x 100 = 1000 mm, , a External door, , = 1.00 x 2.00m to 1.10 x 2.00m, , Height of opening = 21 x 100 = 2100 mm, , b Internal door, , = 0.90 x 2.00m to 1.00 x 2.00 m, , c Doors of bathrooms and closets, = 0.70 x 2.00 to 0.8 x 2.00m, d Carriage of cars, , Door frame, , = 2.25m (height) x 2.25m width, to 2.25m (height) x 2.40 width, II Public building such as schools, hospitals, libraries,, etc., a 1.2m x 2.00m, b 1.2m x 2.10m, 166, , D - Stands for door, T-stands for double shutter. The, thickness of shutter shall be 20,25 or 30 mm depending, upon size., , A door frame is an assembly of horizontal and vertical, members forming an enclosure to which door shutters, are fixed. The vertical members are known as jambs,, posts, while the horizontal top member connecting the, posts is called the head which has horns on both sides., The size of the frame is determined by allowing a, clearance of 5 mm to both the sides and top of an opening, , Construction: Draughtsman Civil - (NSQF Level - 5): Related Theory for Exercise 2.6.78, , Copyright Free under CC BY Licence

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Door frame are made of following matrials., 1 Timber, 2 Steel Section., 3 Aluminum section., , Out of these, timber frames are more commonly used., However in factories, workshops etc steel frames are, used. Aluminium frames are costlier and are used only, for residential buildings where more funds are available., With the increasing cost of timber, concrete frames are, more popular in urban areas., , 4 Concrete., 5 Stone., Classifications, According to arrangement, of components, , On the basis of method, of manner of Construction, , On the basis of working, operation, , Metal doors, , Battened and ledged doors, , Framed and paralled, door, , Revovling door, , Mild steel door, , Battened ledged and braced, doors, , Glazed or sash door, , Sliding door, , Corrugated steel, door, , Battened ledged and framed, , Flush door, , Swing door, , Hollow metal door, , Battened ledged, braced, and framed doors, , Louvered doors, , Collapsible door, , Metal, covered, plywood door, , Wire gauged doors, , Rolling steel shutter door, , Battened and ledged doors (Fig 4), , Battened ledged and braced doors (Fig 5), , This is the simplest type doors, specially suitable for, narrow opening when strength and appearance are not, important. These doors are formed of vertical boards, known as battens which are usually tongued and grooved, and are fixed together by horizontal supports known as, ledges. Batterns are 10-15cm wide and 20mm-30mm, thick. Ledges are generally provided at the top, middle, and bottom. The door is hung to the frame by means of, T-Hinge of iron., , These doors are similar to ledged doors except that, diagonal members known as braces are provided as, shown in figure. The braces are generally 10cm – 15, cm wide and 30 mm thick. The brace give rigidity to the, door and hence doors of this types are useful for wide, opening. It should be noted that braces must slope, upwards from the hanging side as they have to work in, compression and not in tension., , Construction: Draughtsman Civil - (NSQF Level -5): Related Theory for Exercise 2.6.78, , Copyright Free under CC BY Licence, , 167

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Battened ledged and framed doors, , Battened ledged framed and braced doors, , In this type of doors a frame work for shutters are, provided to make the door stronger and better in, appearance as shown in figure. Styles are generally 10cm, wide and 40mm thick. The ledges are provided as usual., The total thickness of styles is made equal to the, thickness of ledges & thickness of batterns., , This is just similar to the battened ledged and framed, doors, except that brace are introduced. This type of door, is durable and stronger and hence it can be used for, external use. The brace must stop upward from hanging, side., , Types of doors - II, Objectives: At the end of this lesson you shall be able to, • explain types of door according to manner of construction (framed and panelled door, glazed or sash door), • explain types of door according to manner of construction (flush door, louvered door and wire gauged door), Framed and panelled door (Fig 1), , Features of framed and panelled door, The styles are made continuous from top to bottom that, is they are in single pieces., Various rail (in top rail, bottom rail and intermediate rail), are jointed to the styles at both the ends., The styles and rails are jointed by tenon and mortised, joints., The bottom and lock rail are made wider than top and, frieze rails., The entire frame is grooved on all the inside face to, receive panels., Additional timber beading is provided on one or both the, sides to improve the elevation of the door., The minimum width of the style is kept as 100mm. The, minimum width of bottom rail and top rail is kept as, 150mm., , These type of doors are widely used in almost all types, of buildings since they are strong and give better, appearance than battened doors. This door consists, of, frame-work in the form of vertical members called styles, and horizontal member called rails which are grooved, along the inner edge of the frame to receive the panels., The panels are made from timber, plywood, block boards,, A.C sheet or even glasses. Panalled doors are of various, types such as., Single panelled doors, Two panelled doors, Three panelled doors, Multiple panelled doors, Panelled doors may contain single leaf for small opening, or may contain two leaves for wider openings. In double, leaf door each leaf has separate frames each hinged to, the corresponding jamb post of the door., 168, , If panels are made timbers, its minimum width should, be 150mm and minimum thickness should be 20mm., However the maximum area of single panel of timber, should not be more than 0.5m2. These districtions do, not apply to panel of plywood, particles boards on hard, board., Glazed or sash door (Fig 2), Glazed or sash door are provided where additional light, is required to be admitted to the room through the door, or where the visibility of the interior of the room is required, from the adjacent room. Such doors are commonly used, in residential as well as public buildings like hospitals,, schools colleges etc. The doors may be within fully, glazed or they may be partially glazed and partially, paneled. In the letter case the ratio of glazed portion to, the paralled portion is kept 2:1 is bottom 1/3rd height is, paralled and top 2/3 height is glazed. The glass is, required into the rebate provided in the wooden sash, bars and secured by rails and putty. Partially glazed doors, , Construction: Draughtsman Civil - (NSQF Level -5): Related Theory for Exercise 2.6.78, , Copyright Free under CC BY Licence

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are sometimes provided with styles which gradually get, diminished at lock rail to improve the elevation or to, permit more area for the glazed panels. Such style which, decrease in width at lock level are called diminishing, style or gun stock rail or gun stock style., , grains of core at right angles to that of the cross bands., Such doors are quiet strong but are heavy and require, more materials., , Flush Door, Flush doors are becoming popular these days because, of their pleasing appearance, simplicity of construction,, less cost, and greater durability. They are used both for, residential as well as public and commercial buildings., These doors consist of solid or semi-solid skeleton or, core covered both sides with plywood, or veneers etc., This door presents a flush and joint less surface which, can be neatly polished., Flush dooors are of two types, a Solid core or laminated core flush door, b Hollow core or celluar core flush door (framed), a Solid core or laminated core flush door, (Fig 3 & 4), Solid core flush door consists of framework in the form, of styles, top and bottom rails of not less than 75 mm, width. The inner space of the frame is provided with block, board or particle board., In the laminated core flush door the wooden strips of, maximum width 25mm are glued together and length of, each strip is equal to the length of the laminated core. It, is housed in the outer frame made of styles, top and, bottom rails of not less than 75 mm width., In each type of core, plywood sheets are glued under, pressure to the assembly of core housed in the frame, on both faces. Alternatively separate cross bands and, face veneers can be glued on both the faces, with the, , b Hollow or cellular core flush door (Framed flush, door) (Fig 5), A hollow core flush door consists of frame made up of, styles, top and bottom rails and a minimum of two, intermediate rails, each of minimum 75 mm width. The, inner spaces of the frame is provided with equally spaced, battens each of minimum 25 mm width, such that the, area of voids is limited to 500 cm2., A cellular core flush door consists of frame work made, of style, top and bottom rails each of 75 mm width. The, , Construction: Draughtsman Civil - (NSQF Level - 5): Related Theory for Exercise 2.6.78, , Copyright Free under CC BY Licence, , 169

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voids space is filled with equally spaced battens of wood, or plywood, each of minimum 25mm width. The battens, are so arranged that the voids space between the, adjacent vertical and horizontal batterns does not exceed, 25 cm2 in area. Total area of voids does not exceed 40%, of the area of the shutter., , Louvered doors permit free circulation of air through them, and at the same time maintain the privacy of the room., However these doors catch dust which is very difficult to, be cleaned. These doors are generally used for latrine, and bathrooms of residential and public buildings. The, doors may be either louvered to its full height or it may, be partially louvered and partially. Panelled. The louverds, are arranged and partially paneled. The louvers are, arranged at such an inclination that vision is obstructed, while they permit free passage of air. This is achieved, by fixing the upper back edge of a louver, higher than, the lower front edge of the louver just above it. Louvers, may be either movable or fixed. In the case of movable, louvers, a vertical piece of timber is provided to which, louvers are attached through hinges. The movement of, louver is activated by the vertical piece of timber. Louvers, may be made of either timber or glass or plywood., Wire gauged doors (Fig 7), , In both types, shutters are formed with, plywood sheets, or cross bands and face veneers which are glued under, pressure to both the faces of core., Louvred or Venetian Door (Fig 6), , These types of doors are provided to check the entry of, flies, mosquitoes, insects etc. Wire mesh is provided in, the panels and therefore they permit free passage of air., Such doors are commonly used for refreshment room,, hotels, cup-boards containing estables in sweet shops, etc. The door is formed of wooden framework consisting, of vertical styles and horizontal rails and the panel, opening are provided with fine mesh of galvanized wire, gauges. The wire gauge is fixed by means of nails and, timber beadings. Generally the door has two shutter is, fully panelled and the outer shutter has wire gauged, panels., 170, , Construction: Draughtsman Civil - (NSQF Level -5): Related Theory for Exercise 2.6.78, , Copyright Free under CC BY Licence

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Types of doors - III, Objectives: At the end of this lesson you shall be able to, • explain types of doors according to working operation., 1 Revolving Doors (Fig 1), , In this type of door, the shutter slides on the side with, help of runner and guide rails. The shutter may be of, one or several leaves and can slide either on one side or, both the sides. Cavities may be provided in the wall to, receive the door in an open position or it may be simply, lie touching the wall. As sliding door does not cause any, obstruction during movement, it is used for entrance of, godowns, sheds, shops, show rooms etc. It is provided, with handles, locking arrangement, stopper etc., Swing Door (Fig 3), , Such doors are provided only in public buildings such as, libraries, museums, and banks etc. where there are, contant visitors. Such doors provide entrance to one, person and exit another person simultaneously and close, automatically when not in use. This door is also suitable, for air conditioned buildings and buildings at places where, strong breeze blow throughout the year, since the door, is so assembled that it excludes the wind drought. The, door many consist of centrally placed mullion to which, four radiating shutters are provided. The mullion or, vertical timber is supported on ball bearings at the bottom, and has bush bearing at the top so that it rotation is, without any jerk, friction and noise. The shutters may be, fully glazed, fully paneled or partially glazed and partially, parelled. The shutters and the mullion are enclosed in a, vestibule. Vertical rubber piece are provided at the, rubbing ends of shutters to prevent draught of air. The, radiating shutter can be folded when traffic is more. The, opening can also be closed., Sliding Door (Fig 2), , A swing door has its shutter attached to the door frames, by means of special double action spring hinges so that, the shutter moves both inward and outward as desired., Generally such doors have single leaf, but two leaves, can also be provided. Such doors are not rebated at the, meeting styles. The closing edge of which should be, segmental when the door is to be used, a sight push is, made and the action of spring brings the shutter to closed, position. The return of the shutter is with force and hence, in order to avoid the accident, either the door should be, fully glazed or a peep hole should be provided at the, eyelevel as shown in figure 3., Collapsible Steel Door (Fig 4), A collapsible door may consist of a mild steel frame. Two, vertical pieces of mild steel channels about 15 to 20 mm, wide are jointed together with the hollow portion of the, channel insides; so that a vertical gap is created. Such, channel units are spaced at 100-120 mm apart and are, braced with flat iron diagonals 10-20mm wide and 5 mm, thick. These diagonals allow the shutter to open out or, get closed. The door can be opened or closed by a slight, push or pull. A collapsible door thus work without hinges., It is used for compound gate, residential building, sheds,, godown etc., , Construction: Draughtsman Civil - (NSQF Level -5): Related Theory for Exercise 2.6.78, , Copyright Free under CC BY Licence, , 171

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A rolling steel shutter may consist of a frame, a drum, and a shutter of thin steel plate or iron sheet of thickness, about 1mm. Grooves of about 25 mm thickness are left, in the frame. A horizontal shaft and springs are provided, in the drum at the top. The diameter of drum is about 20, cm – 30 cm. The shutters are usually rolled in turns., Thus a slight push or pull will open or closed the shutter., Rolling steel shutter doors are sufficiently strong and they, can be easily rolled up or down. They cause no, obstruction to the floor as well as openings. Rolled steel, shutter door are usually provided for garages,, showrooms, shops, godowns etc. They provide security, against fire, but the appearance is not good. They cause, noise in movement., Rolling Shutters are two types:, i, , Pull push type rolling shutters provided for door, opening area less than 10m2, , ii Mechnical gear type rolling shutters provide for door, opening are greater than 10 m2, , Rolling Steel Shutter (Fig 5), , 172, , Construction: Draughtsman Civil - (NSQF Level -5): Related Theory for Exercise 2.6.78, , Copyright Free under CC BY Licence

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Construction, Related Theory for Exercise 2.6.79 & 2.6.80, Draughtsman Civil - Carpentry joints, Windows and ventilators, Objectives: At the end of this lesson you shall be able to, • enumerate factors for selection of size, location & no. of windows in a room, • describe Indian standard recommendations of windows, • explain different types of windows and ventilators., Introduction, , Based on these factors the following thumb rules are in, use., , Windows: Windows are necessary for ventilation and, lighting. These are usually glazed with clear or opaque, glasses. As already stated, not less than 10 t0 15 percent, of the floor area of a room is given to windows opening, to the outside. The smaller the floor area, the larger will, be the percentage., , 1 Breath of window = 1/8 (Width of room + Height of, room), 2 The total area of window opening normally varies from, 10-12% of the floor areas of the room depending upon, the climatic conditions., 3 The area of window opening should be at least 1 sq.m, for every 30-40 cubic metre of the room volume., , Ventilators, Ventilators are windows of small heights and they are, fixed at the top of door or window. The ventilators are, provided with glass panels and steel grill is fixed in, ventilator for the purpose of safety., , 4 In public buildings, the minimum area of window, should be 20% of floor areas., 5 For sufficient natural light, the area of the glazed panels, should at least be 8-10% of the floor area., , Windows, The selection of size, shape location and no. of windows, in a room depends upon the following factors., 1 Size of the room, 2 Location of the room, 3 Utility of the room, , Indian standard recommends that the size of window, frame. Should be derived after allowing a margin of 5, mm all round an opening for convenience of fixing. The, width and height of an opening is indicated by a number, of modules, where each module is of 100 mm. A, designation 6ws 12 indicates a window opening with, single shutter having width equal to 6 modules., It, 6 x 100 = 600 mm, , 4 Direction of the wall, 5 Direction of the wind, , And height equal to 12 modules, , 6 Climatic conditions such as humidity, temperature etc., It, 12 X 100 = 1200 mm, , 7 Requirement of exterior view, 8 Architectural treatment to the exterior of the building., , Sl No, , Designation, , Size of Opening, , Indian standard recommendations for size of opening, size of frame and size of window shutters are given, below:, , Size of Window frame, , Size of window shutters, , 1, , 6 WS 12, , 600 x 1200, , 590 x 1190, , 560 x 110, , 2, , 10 WT 12, , 1000 x 1200, , 990 x1190, , 460 x 1100, , 3, , 12 WT 12, , 1200 x 1200, , 1190 x 1190, , 560 x 1100, , 4, , 6 WS 13, , 600 x 1300, , 590 x 1290, , 560 x 1200, , 5, , 10 WT 13, , 1000 x 1300, , 990 x 1290, , 460 x 1200, , 6, , 12 WT 13, , 1200 x 1300, , 1190 x 1290, , 560 x 1200, , 173, , Copyright Free under CC BY Licence

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Types of Windows, The Common Verities of windows used in building, construction are as follows:, 1 Fixed Window, 2 Pivoted window, 3 Double hung window, 4 Casement window, 5 Sliding window, 6 Sash window, 7 Louvered window, 8 Metal window, 9 Bay window, 10 Clerestorey window, 11 Dormer window, 12 Corner window, 13 Gable window, 14 lantern window, 15 Sky lights, 16 Ventilators, 17 Combined windows and Ventilators., Fixed Window (Fig 1), These windows are provided for the only purpose of, admitting light and providing vision in the room. This, window may consist of a window frame to which shutters, are fixed. No rebate are provided to the window frame., The shutters are fully glazed., Pivoted window (Fig 1), In this type of window the shutter is capable of rotating, about a pivot fixed to window frame. The window frame, has no rebate. The shutter can rotate horizontally or, vertically depending upon the position of pivot., Double – hung window (Fig 2), This type of window consist of a pair of shutters arranged, one above the other which can slide vertically within the, grooves provided in the frame. A pair of metal weights, connected by chain passing over pulleys, is provided for, each shutter. By this arrangement the window can be, opened at top or bottom to the desired extent by pulling, the metal weight suitably. Thus in this type of window, it, is possible to have controlled ventilation. In addition,, the shutter can also be cleaned easily., , 174, , Casement window (Fig 3), Window where shutters open like door are called, casement windows. The window has a frame which is, rebated to receiving the shutters. The shutters consist, of style, top rail, bottom rail and intermediate rail, thus, dividing it into panels. The panel may be glazed or, unglazed or partially unglazed. In case of windows with, double shutters, the outer shutter may have wire-gauged, panels., , Construction: Draughtsman Civil - (NSQF Level -5): Related Theory for Exercise 2.6.79 & 80, , Copyright Free under CC BY Licence

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Sliding Window, In this type of window the shutters move on roller and, can slide horizontally or vertically similar to slding door., Sash or glazed window, In this case the window shutter consists two vertical, styles, top and bottom rails. The panel space of window, shutter between the style and rail is fixing divided by sash, bars into panels of small size for fixing glass panels. The, glass panels are secured in position either by putty or by, fillets, known as glazing beads., , Steel window can be fixed direct in the masonry opening, in the wall or it may be fitted in a wooden frame fixed in, a window opening in the wall. It should be ensured that, no load of the wall etc, is transferred to the window frame., For this it is usual practice to keep the size of the window, opening slightly more than that of window frame. Also, the frame may be fixed in the opening after the masonry, work is complete., Method of fixing metal windows (Steel windows), The prepared opening in which steel window frame is to, be fixed is cleaned and exact position of the window, frame is maked by drawing lines., , Louvered window (Venetian window) (Fig 4), In this type of windows the lowers are provided as in the, case of louvered doors. They allow free passage or air, when close and at the same time they maintain sufficient, privacy. The shutter consists of top rail, bottom rail and, two styles; which are grooved to receive the louvers. The, economical angle of inclination of the louvers is 450 and, they are generally fixed in position., Metal window, These are now a day’s widely used especially in public, buildings. Windows are made of metals like mild steel,, glavanised mild steel, aluminimum, bronze, stainless, steel etc. Bronze, aluminium and stainless steel are, considered to be the best as they process high degree, of elegance, finishing, durability and are dust-proof as, well. Mild steel being cheapest of the above metals, steel, window works out to be the most economical. Hence, steel windows are extensively used in all types of, buildings., , The distance of fixing holes on the frame are measured, and these positions are marked on the chalk line drawn, in the opening., Holes are cut in brick masonry of size 5 m2 and 5-10cm, deep to accommodate hold fast or legs. In case of stone, masonry or R.C.C work where it is difficult to cut holes, for legs, wooden plugs are embedded at appropriate, places during the construction itself. The window frame, is then fixed to these plugs with the help of galvanized, iron or wood screws., The frame is placed in the opening and position is, adjusted in correct alignment by striking wooden wedges, in correct position. Since there is a little gap between the, opening and window frame temporary wooden wedges, can be easily driven after adjusting the window in correct, alignment the legs are screwed light in the frame., Legs are grouted into the holes with cement mortar. After, grout has set, wooden wedges are removed and space, , Construction: Draughtsman Civil - (NSQF Level - 5): Related Theory for Exercise 2.6.79 & 80, , Copyright Free under CC BY Licence, , 175

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between the opening and frame is filled with cement, mortar., Following precaution is to be taken in metal, windows:, The members of the frame and sash should be properly, welded at corners., Precaution should be taken to prevent the corrosion of, metal windows., Glasses panels should be properly fixed., The metal frame should be embedded in cement or, bituminous mastic to prevent the entry of moisture on, rain water., , Clere – storey window (Fig 6), These windows are provided near the top of main roof., The pivoted windows are used for this purpose. The, clere-storey windows provide ventilation to the inside of, the room where the front is blocked by veranda and, improved the appearance of the building., , It is advisable to check and slightly adjust the movement, of shutter before erecting the window in the opening., The handles to the window should be fixed before doing, the glazing work., Scaffolding members or any other support should not, be tilt down the metal windows. Otherwise the window, will be damaged., The masonry opening to receive the metal window should, be prepared in proper level and plumb., Following are the advantages of steel windows over, wooden windows, The steel windows are factory made products and hence, they possess greater precision as compared to the, wooden windows., The steel windows are not subjected to contraction and, expansion due to whether effects as sin the case of, wooden windows., The steel windows exhibit elegant appearance., , Dormer Window (Fig 7), , The members of steel windows are narrow and hence, the steel windows admit more light and ventilation for, the same area as compared to the wooden windows., The steel windows are highly termite proof and fire proof., Steel windows are more durable and stronger as, compared to wooden windows., Bay windows (Fig 5), Bay windows project outside the external walls of a room., This projection may be triangular, circular, rectangular, or polygonal in plan. Such a window is provided to get, an increased area of opening for admitting more light, and air. They also provide extra space in the room, and, improved the overall appearance of the building., 176, , A dormer window is a vertical window built in the sloping, side of the pitched roof. This window is provided to, achieve proper ventilation and lighting of the enclosed, , Construction: Draughtsman Civil - (NSQFLevel -5): Related Theory for Exercise 2.6.79 & 80, , Copyright Free under CC BY Licence

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spaces below the roof. Dormer window also serves as, an architectural feature of the building., , The windows provided a in the gable end of a pitched, roof are known as a gable windows., , These are the windows which are fixed on flat roofs to, provide light to the inner portion of the building where, light coming from the windows in external wall is in, sufficient. They may be square or rectangular or curved., Glass panels are generally fixed; but if ventilation is, required in addition to light, then pivot window may be, provided., , Corner window (Fig 8), , Sky light (Fig 10), , Gable Window (Fig 7), , These windows are provided at the corner of the room, and thus they have two faces and two directions. Due to, this there is entry of light and air from two directions and, in many cases the elevation of the building is also, improved. However special lintel will have to be casted, at the corner and jamb posts of the window at the corner, will have to be made of heavy section., Lantern Window (Fig 9), , A sky light is provided on a sloping roof to admit light., The window project above the sloping surface and is, parallel to the sloping roof surface. The sky light is, provided with a view to permit the room below to be fully, lighted with natural light. The opening for sky light is made, by cutting the common rafters., Ventilators, Ventilators are small windows fixed at a greater height, than the window, generally about 30-50cm below the roof, level. The ventilator has a frame and a shutter generally, glazed and horizontally pivoted. The top edge of the, shutter open inside the bottom edge open outside so, that rain water is excluded., Ventilators combined with window or door, Ventilators may be provided in continuation of a door or, a window at its top. Such a ventilator is known as Fanlight. The construction of a fan light is similar to sash, window. Such a ventilator is usually hinged at top and, can open out. Alternatively, the ventilator shutter can he, hinged at the bottom., , Construction: Draughtsman Civil - (NSQF Level -5): Related Theory for Exercise 2.6.79 & 80, , Copyright Free under CC BY Licence, , 177

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Fixtures and fastenings, Objective: At the end of this lesson you shall be able to, • explain types of fixtures and fastenings., Introduction, Various types of fastenings are employed for connecting, and maintaining the joints. The basic objects of different, fastening and their important features are given below:, Fixtures and fastenings, The following types of fixtures and fastenings are required, for doors, windows and ventilators., 1 Hinges, 2 Bolts, 3 Handles, 4 Locks., , d Garnet hinge: This type of hinge is also known as, T-hinge and is commonly used for battened, ledged, and braced doors. (Fig 4), , 1 Hinges, Following types of hinges are used for doors, windows, and ventilators., a Black flap hinge: These hinges are used where the, shutters are thin. These are fixed on backside of the, shutter and frame. (Fig 1), , b Butt Hinge: These hinges are commonly used for, fixing door and window shutters to the frame. (Fig 2), , e Parliamentary Hinge: These hinges permit the door, shutters, when open, the rest parallel to the wall., Hence these hinges are used where the opening is, narrow and when it is required to keep the opening, free from obstruction due to door shutters. (Fig 5), , f, , c Counter-Flap hinge: This type of hinge has three, parts and two centres. Provision of this type of hinge, enable the shutter to be folded back to back (Fig 3), , 178, , Pin hinge: This is used for heavy door shutters. The, centre pin of the hinge can be removed and the two, leaves or straps of the hinge can be fixed separately, to the frame and the shutter. (Fig 6), , g Strap hinge: It is used for ledged and braced door, and for heavy doors such as for garages, stables gate, etc. (Fig 7), , Construction: Draughtsman Civil - (NSQF Level -5): Related Theory for Exercise 2.6.79 & 80, , Copyright Free under CC BY Licence

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h Spring hinges: Single acting or double acting hinges, are used for swinging doors, single acting hinge is, used when door shutter opens only in one direction, while the double acting hinge is used when shutter, swings in both the directions. The door closes, automatically due to spring action (Fig 8), , i, , Rising butt hinge: Such hinges are used for doors, of rooms having carpet etc. They are used in place, of ordinary butt hinges. The door is closed, automatically, due to which the shutter is raised by, 10 mm on being opened (Fig 9), , c Tower bolt: This is similar to barrel bolt except that, instead of barrel bolt are two or three staples, (Fig 12), d Flush bolt: This bolt is used when it is desired to, keep the bolt flush with the face of the door (Fig 13), , Bolts, Following are the various type of bolts used for doors, and windows:, a Aldrop: It is fixed on external doors where pad locks, are to be used (Fig 10), b Barrel bolt: It is used for fixing back faces of doors., The socket is fixed to the door frame while the plate, is succeeded to the inside of the shutter (Fig 11), , e Hasp and Staple bolt: This is used for external doors, where padlock is to be used. The staple is fixed to, the door frame while hasp is fixed to the shutter, (Fig 14), f, , Latch : This is made of iron, it consists of lever pivoted, at one end. The Liver is secured in a hasp and staple., It is fixed to the inside face of the door (Fig 15), , Construction: Draughtsman Civil - (NSQF Levl -5): Related Theory for Exercise 2.6.79 & 80, , Copyright Free under CC BY Licence, , 179

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Locks, a Hook and Eye: This is used for keeping the window, shutter in position when the window is opened, (Fig 16), , b Cup-board lock: It is used to secure doors of minor, importance (Fig 17), , c Mortice lock: It is fixed in mortice formed on the edge, of a door (fig 18), , d Peg Stay: It is used for steel windows. The width of, opening can be adjusted by holes which are provided, in the peg stay (Fig 19), e Pad lock: It is used for securing doors when all, drop bolts and hasp and staple bolts are employed, (Fig 20), f, 180, , Rim Lock : It is used for thin doors (Fig 21), , Construction: Draughtsman Civil - (NSQF Level - 5): Related Theory for Exercise 2.6.79 & 80, , Copyright Free under CC BY Licence

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Construction: Draughtsman Civil - (NSQF Lesvel -5): Related Theory for Exercise 2.6.79 & 80, , Copyright Free under CC BY Licence, , 181

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Construction, Draughtsman Civil - Electrical wiring, , Related Theory for Exercise 2.7.81, , Safety Precaution, Objectives: At the end of this lesson you shall be able to, • state the importance of safety, • list out the safety precautions to be observed in a machine shop, • list out the personal safety precautions to be observed, • list out the safety precautions to be observed while working on the machines., Generally accidents do not happen, they are caused., Most accident are avoidable. A good craftmans, having, a knowledge of various safety precautions’, can avoid, accidents to himself and to his fellow workers and protect, the equipment from any damage. To achieve this, it is, essential that every person should follow safety, procedure. (Fig 1), , Don’t walk under suspended loads., Don’t cut practical jokes while on work., Use the correct tools for the job., Keep the tools at their proper place., Wipe out split oil immediately., Replace worn out or damaged tools immediately., Never direct compressed air at yourself or at your coworker., Ensure adequate light in the workshop., Clean the machine only when it is not in motion., Sweep away the metal cuttings., Know everything about the machine before you start it., Personal Safety, Wear a one piece overall or boiler suit., Keep the overall buttons fastened., Don’t use ties and scarves, Roll up the sleeves tightly above the elbow., , Safety in a workshop can be broadly classified into 3, categories., , Wear safety shoes or boots or chain., , •, , General Safety, , Cut the hair short., , •, , Personal Safety, , Don’t wear a ring, watch or chain., , •, , Machine Safety, , Never lean on the machine., , General Safety, , Don’t clean hands in the coolant fluid., , Keep the floor and gangways clean and cleaner., Move with care in the workshop, do not run., Don’t leave on the machine which is in motion., , Don’t remove guards when the machine is in motion., Don’t use cracked or chipped tools., Don’t start the machine until., , Don’t touch or handle any equipment / machine unless, authorized to do so., 182, , Copyright Free under CC BY Licence

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•, , The work piece is securely mounted., , Keep the machine clean., , •, , The feed machinery is in the neutral., , •, , The work area is clear,, , Replace any worn out or damaged accessories, holding, devices, nuts, bolt etc. as soon as possible., , Don’t adjust clamps or holding devices while the machine, is in motion., Never touch the electrical equipment with wet hands., Don’t use any faulty electrical equipment., Ensure that electrical connections are made by an, authorized electrician only., , Do not attempt operating the machine until you know, how to operate it properly., Do not adjust tool or the work piece unless the power is, off., Stop the machine before changing the speed., Disengage the automatic feeds before switching off,., , Concentrate on your work., , Check the oil level before starting the machine., , Have a calm attitude., , Never start a machine unless all the safety guards are n, position., , Do things in a methodical way., Don’t engage yourself in conversation with others while, concentrating on your job., Don’t distract the attention of others., Don’t try to stop a running machine with hands., , Take measurements only after stopping the machine., Use wooden planks over the bed while loading and, unloading heavy jobs., Safety is a concept, understand it, Safety is a habit, Cultivate it., , Machine Safety, Switch off the machine immediately if something goes, wrong., , Safety signs, Objectives: At the end of this lesson you shall be able to, • list three kinds of road sign, • describe the marking on the road, • describe the various police traffic hand signal and light signal, • list the collision causes., In olden days road locomotive carrying a red flag by day, and red lantern by night. Safety is the prime motive of, every traffic., , Mandatory Sign (Fig 1), , Kinds of Road Signs, , Violation of mandatory sign can lead to penalties., Ex. stop, give way, limits prohibited, no parking are, compulsory sign., , Mandatory, , Cautionary Signs (Fig 2), , Cautionary and, , Cautionary /warning signs are especially safe. Do’s and, don’ts for pedestrians, cyclists, bus passengers and, motorists., , Information., , Information signs (Fig 3), , Construction: Draughtsman Civil - (NSQF Level - 5): Related Theory for Exercise 2.7.81, , Copyright Free under CC BY Licence, , 183

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Basic first- aid treatment, Objectives: At the end of this lesson you shall be able to, • state the first aid, • list the key aims of first aid, • explain the ABC of the first aid, • brief how to give first -aid treatment for a victim who needs first aid., unconscious patients, which is choking on regulated, stomach contents. The airway can also become, blocked through a foreign object becoming lodged in, the pharynx or larynx, commonly called choking. The, first aider will be taught to deal with this through a, combination of ‘backslaps’ and ‘abdominal thrusts’., Once the airway has been opened, the first aider, would assess to see if the patient is breathing., , First aid is defined as the immediate care and support, given to an acutely injured or ill person, primarily to save, life, prevent further deterioration or injury, plan to shift, the victim to safer place, provide best possible comfort, and finally help them to reach the medical centre/ hospital, through all available means. It is an immediate lifesaving procedure using all resources available within, reach., Imparting knowledge and skill through institutional, teaching at younger age group in schools, colleges, entry, point at industry level is now given much importance., Inculcating such habits at early age, helps to build good, healthcare habits among people., First aid procedure often consists of simple and basic, life saving techniques that an individual performs with, proper training and knowledge., The key aims of first aid can be summarized in three, key points:, •, , Preserve life: If the patient was breathing, a first, aider would normally then place them in the recovery, position, with the patient leant over on their side, which, also has the effect of clearing the tongue from the, pharynx. It also avoids a common cause of death in, , 184, , •, , Preserve further harm: Also sometimes called, prevent the condition from worsening, or danger of, further injury, this covers both external factors, such, as moving a patient away from any cause of harm,, and applying first aid techniques to prevent worsening, of the condition, such as applying pressure to stop a, bleed becoming dangerous., , •, , Promote Recovery: First aid also involves trying to, start the recovery process from the illness or injury,, and in some cases might involve completing a, treatment, such as in the case of applying a plaster, to a small would., , Training, Basic principles, such as knowing to use an adhesive, bandage or applying direct pressure on a bleed, are often, , Construction: Draughtsman Civil - (NSQF Level - 5): Related Theory for Exercise 2.7.81, , Copyright Free under CC BY Licence

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acquired passively through life experiences. However,, to provide effective, life-saving first aid interventions, requires instruction and practical training. This is, especially true where it relates to potentially fatal illnesses, and injuries, such as those that require cardiopulmonary, resuscitation (CPR); these procedures maybe invasive,, and carry risk of further injury to the patient and the, provider. As with any training, it is more useful if it occurs, before an actual emergency, and in many countries,, emergency ambulance dispatchers may give basic first, aid instructions over the phone while the ambulance is, on the way. Training is generally provided by attending, a course, typically leading to certification. Due to regular, changes in procedures and protocols, based on updated, clinical knowledge, and to maintain skill, attendance at, regular refresher courses or re-certification is often, necessary. First aid training is often available through, community organization such as the Red cross and St., John ambulance., ABC of first aid, ABC stands forairway, breathing and circulation., •, , Airway: Attention must first be brought to the airway, to ensure it is clear. Obstruction (choking) is a life, threatening emergency., , •, , Breathng: Breathing if stops, the victim may die, soon. Hence means of providing support for breathing, is an important next steps. There are several, methods practiced in first aid., , •, , Circulation: Blood circulation is vital to keep person, alive. The first aiders now trained to go straight to, chest compression through CPR methods., , When providing first aid one needs to follow some rule., There are certain basic norms in teaching and training, students in the approach and administration of first aid, to sick and injured., , Surroundings play vital role, Different surroundings require different approach. Hence, first aider should study the surrounding carefully. In other, words, one need to make sure that they are safe and, are not in any danger as it would be of no help that the, first aider himself get injured., Do No Harm, Most often over enthusiastically practiced first aid viz,, administering water when the victim is unconscious,, wiping clotted blood (which acts as plug to reduce, bleeding), correcting fractures, mishandling injured parts, etc., would leads to more complication. Patients often, die due to wrong FIRST AID methods, who may, otherwise easily survive. Do not move the injured person, unless the situation demands. It is best to make him lie, wherever he is because if the patient has back, head or, neck injury, moving him would causes more harm., This does not mean do nothing. It means to make sure, that to do something the care givers feel confident, through training would make matters safe. If the first aider, is not confident of correct handling it is better not to, intervene of doing it. Hence moving a trauma victim,, especially an unconscious one, needs very careful, assessment. Removal of an embedded objects (Like a, knife, nail) from the wound may precipitate more harm, (e.g. increased bleeding). Always it is better to call for, help., Reassurace, Reassure the victim by speaking encouragingly with him., Stop the bleeding, If the victim is bleeding, try to stop the bleeding by, applying pressure over the injured part., Golden Hours, , Not to get panic, Panic is one emotion that can make the situation more, worse. People often make mistake because they get, panic. Panic clouds thinking may cause mistakes. First, aider need calm and collective approach. If the first aider, himself is in a state of fear and panic gross mistakes, may result. It’s far easier to help the suffering, when they, know what they are doing, even if unprepared to, encounter a situation. Emotional approach and response, always lead to wrong doing and may lead one to do wrong, procedures. Hence be calm and focus on the given, institution. Quick and confident approach can lessen the, effect of injury., , India have best of technology made available in hospitals, to treat devastating medical problems viz. head injury,, multiple trauma, heart attack, stokes etc, but patients, often do poorly because they don’t gain access to that, technology in time. The risk of dying from these, conditions, is greatest in the 30 minutes, often instantly., This period is referred to as Golden period. By the time, the patent reach the hospital, they would have passed, that critical period. First aid care come handy to save, lives. It helps to get the nearest emergency room as, quickly as possible through safe handling and, transportation. The shorter that time, the more likely the, best treatment applied., , Call Medical Emergencies, If the situation demands, quickly call for medical, assistance. Prompt approach may save the life., , Construction: Draughtsman Civil - (NSQF Level - 5): Related Theory for Exercise 2.7.81, , Copyright Free under CC BY Licence, , 185

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Maintain the hygiene, Most important, the first aider need to wash hands and, dry before giving any first aid treatment to the patient or, wear gloves in order to prevent infection., , Assess the urgency of the situation. Before you report, an emergency, make sure the situation is genuinely, urgent. Call for emergency services if you believe that a, situation is life-threatening or otherwise extremely critical., •, , A crime, especially one that is currently in progress., If you’re reporting a crime, give a physical description, of the person committing the crime., , •, , A fire- if you’re reporting a fire, describe how the fire, started and where exactly it is located. If someone, has already been injured or is missing, report that as, well., , •, , A life- threatening medical emergency, explain how, the incident occurred and what symptoms the person, currently displays., , •, , A car crash – Location , serious nature of injures,, vehicle’s details and registration, number of people, involved etc., , Cleaning and dressing, Always clean the wound thoroughly before applying the, bandage gently wash the wound with clean water., Not use local medications on cuts or open wounds:, They are more irritating to tissue than it is helpful Simple, dry cleaning or with water and some kind of bandage, are best., CPR (Cario-Pulmonary Resuscitation) can be lifesustaining, CPR can belief sustaining. If one is trained in PR and, the person is suffering from choking or finds difficulty in, breathing, immediately begin CPR. However, if one is, not trained in CPR, do not attempt as you can cause, further injury. But some people do it wrong. This is a, difficult procedure to do in a crowded area. Also there, are many studies to suggest that no survival advantage, when bystanders deliver breaths to victims compared to, when they only do chest compressions. Second, it is very, difficult to carry right maneuver in wrong places. But, CPR, if carefully done by highly skilled first aiders is a, bridge that keeps vital organs oxygenated until medical, team arrives., , Call Emergency Service, The emergency number varies – 100 for Police & Fire,, 108 for Ambulance., Report your location, The first thing the emergency dispatcher will ask is where, you are located, so the emergency services can get there, as quickly as possible. Give the exact street address, if, you’re not sure of the exact address, give approximate, information., Give the dispatcher your phone number, , Declaring death, It is not correct to declare the victim’s death at the, accident site. It has to be done by qualified medical, doctors., How to report an emergency, Reporting an emergency is one of those things that, seems simple enough, until actually when put to use in, emergency situations. Senses of shock prevail at the, accident sites. Large crowd gather around only with, inquisitive nature, but not to extend helping hands to the, victims. This is common in road side injuries. No passerby would like to get involved to assist the victims. Hence, first aid management is often very difficult to attend to, the injured persons. The first aiders need to adapt multi, task strategy to control the crowd around, communicate, to the rescue team, call ambulance etc., all to be done, simultaneously. The mobile phones help to a greater, extent for such emergencies. Few guidelines are given, below to approach the problems to the rescue team, call, ambulance etc. all to be done simultaneously. The mobile, phones helps to a greater extend to such emergencies., , This information is also imperative for the dispatcher to, have, so that he or she is able to call back if necessary., Describe the nature of the emergency, Speak in a calm, clear voice and tell the dispatcher why, you are calling. Give the most important details first, then, answer the dispatcher’s follow-up question as best as, you can., Do not hand up the phone until you are instructed to do, so. Then follow the instructions you were given., How to do basic first aid?, Basic first aid refers to the initial process of assessing, and addressing the needs of someone who has been, injured or is in physiological distress due to choking, a, heart attack, allergic reactions, drugs or other medical, emergencies. Basic first aid allows one to quickly, determine a person’s physical condition and the correct, course of treatment., , Few guideliens are given below to approach the, problems., 186, , Construction: Draughtsman Civil - (NSQF Level - 5): Related Theory for Exercise 2.7.81, , Copyright Free under CC BY Licence

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Important guideline for first aiders, , Look, listen and feel for signs of breathing, , Evaluate the situation, , Look for the victim’s chest to raise and fall, listen for, sounds of breathing., , Are there things that might put the first aider at risk. When, faced with accidents like fire, toxic smoke, gasses, an, unstable building, live electrical wires or other dangerous, scenario, the first aider should be very careful not to rush, into a situation, which may prove to be fatal., , If the victim is not breathing, see the section below, •, , Remember A - B - Cs, The ABCs of first aid refer to the three critical things the, first aiders need to look for., •, , Airway – Does the person have an unobstructed, airway?, , •, , Breathing – Is the person breathing?, , •, , Circulation – Does the person show a pulse at major, pulse points (wrist, carotid artery, groin), , Avoid moving the victim, Avoid moving the victim unless they are immediate, danger. Moving a victim will often make injuries worse,, especially in the case of spinal cord injuries., , Check the victim’s circulation, Look at the victim’s colour and check their pulse (the, cardiac artery is good option; it is located on either side, of the neck, below the jaw bone). If the victim does not, have a pulse, start CPR., Treat bleeding, shock and other problems as needed, After establishing that the victim is breathing and has a, pulse, next priority should be to control any bleeding., Particularly in the case of trauma, preventing shock is, the priority., •, , Stop Bleeding: Control of bleeding is one of the, most important things to save a trauma victim. Use, direct pressure on a wound before trying any other, method of managing bleeding., , •, , Treat Shock: Shock may causes loss of blood flow, from the body, frequently follows physical and, occasionally psychological trauma. A person in shock, will frequently have ice cold skin, be agitated or have, an altered mental status, and have pale colour to the, skin around the face and lips. Untreated, shock can, be fatal. Anyone who has suffered a severe injury or, life - threatening situation is at risk for shock., , •, , Choking Victim: Choking can cause death or, permanent brain damage within minutes.·, , •, , Treat a burn: Treat first and second degree burns by, immersing or flushing with cool water. Don’t use, creams, butter or ointments, and so not pop, blisters.Third degree burns should be covered with a, damp cloth. Remove clothing and jewellery from the, burn, but do not try to remove charred clothing that is, stuck to burns., , •, , Treat a concussion: If the victim has suffered a blow, to the head, look for signs of concussion. Common, symptoms are: loss of consciousness following the, injury, disorientation or memory impairment, vertigo,, nausea, and lethargy., , •, , Treat a spinal injury victim: If a spinal injury is, suspected, it is especially critical, not move the, victim’s head, neck or back uniess they are in, immediate danger., , Call Emergency Services, Call for help or tell someone else to call for help as soon, as possible. If alone at the accident scene, try to establish, breathing before calling for help, and so do not leave the, victim alone unattended., Determine responsiveness, If a person is unconscious, try to rouse them by gently, shaking and speaking to them., If the person remains unresponsive, carefully, roll them on the side (recovery position) and, open his airway., •, , Keep head and neck aligned., , •, , Carefully roll them onto their back while holding his, head., , •, , Open the airway by lifting the chin (Fig 1), , If the victim is breathing, but unconscious, roll them, onto their side, keeping the head and neck aligned, with the body. This will help drain the mouth and, prevent the tongue or vomit from blocking the airway., , Construction: Draughtsman Civil - (NSQF Level - 5): Related Theory for Exercise 2.7.81, , Copyright Free under CC BY Licence, , 187

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•, , Stay with the victim until help arrives: Try to be a, calming presence for the victim until assistance can, arrive., , Unconsciousness (COMA), Unconscious also referred a Coma, is a serious life, threatening condition, when a person lie totally senseless, and do not respond to calls, external stimulus. But the, basic heart, breathing, blood circulation may be still intact,, or they may also be failing. If unattended it may lead to, death., The condition arises due to interruption of normal brain, activity. The causes are too many., •, , Shock (Cardiogenic, Neurogenic), , •, , Head Injury (Concussion, Compression), , •, , Asphyxia (Obstrution to Air passage), , •, , Extreme of body temperature (Heat, Cold), , •, , Cardiac Arrest (Heart Attack), , •, , Stroke (Cerbro-Vascular accident), , •, , Blood loss (Haemorrhage), , •, , Dehydration (Diarrohea & Vomitting), , •, , Diabetes (Low or high sugar), , •, , Blood pressure (Very low or Very high), , •, , Over dose of alcohol, drugs., , •, , Poisoning (Gas, Pesticides, Bites), , •, , Epileptic Fits (Fits), , •, , Hysteria (Emotional, Psychological), , • If the person is breathing and lying on the back and, after ruling out spinal injury, carefully roll the person, onto the side. Preferably left side. Bend the top legso, both hip and knee are at right angles. Gently tilt the, head back to keep the airway open. If breathing or, pulse stops at any time, roll the person on to his back, and begin CPR., •, , If there is a spinal injury, the victims position may have, to be carefully assessed. If the person vomits, roll, the entire body at one time to the side. Support the, neck and back to keep the head and body in the, same position while you roll., , •, , Keep the person warm until medical help arrives., , •, , If you see a person fainting, try to prevent a fall. Lay, the person flat on the floor and raise the level of feet, above and support., , •, , If fainting is likely due to low blood sugar, give the, person something sweet to eat or drink when they, become conscious., , Do Not, •, , Do not give an unconscious person any food or drink., , •, , Do not leave the person alone., , •, , Do not place a pillow under the head of an, unconscious person., , •, , Do not slap an unconscious person’s face or splash, water on the face and try to revive him., Loss of consciousness may threaten life if the, person is on his back and the tounge has, dropped to the back of the throat, blocking the, airway. Make certain that the person is, breathing before looking for the cause of, unconsciousness. If the injuries permit, place, the casualty in the recovery position (Fig 2), with the neck extended. Never give any thing, by mouth to an unconscious casualty., , The following symptoms may occur after a person has, been unconscious:, •, , Confusion, , •, , Dowsiness, , •, , Headache, , •, , Inabiity to speak or move parts of his or her body, (see stroke symtoms), , •, , Light headedness., , •, , Loss of bowel or bladder control (incontinence), , •, , Rapid heartbeat (Palpitation), , •, , Stupor, , First Aid, , How to diagnose an unconscious injured person, , •, , Call EMERGENCY number., , •, , •, , Check the person’s airway, breathing, and pulse, frequently. If necessary, begin rescue breathing and, CPR., , Consider alcohol: Look for signs of drinking, like, empty bottles or the smell of alcohol., , •, , Consider epilepsy: Are there signs of a violent, seizure, such as saliva around the mouth or generally, disheveled scene?, , 188, , Construction: Draughtsman Civil - (NSQF Level - 5): Related Theory for Exercise 2.7.81, , Copyright Free under CC BY Licence

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•, , Think Insulin: Might the person be suffering from, insulin shock (see ‘How to diagnose and treat insulin, shock”)?, , •, , Think about drugs: Was there an overdose? Or, might the person have under dosed – that is not taken, enough of prescribed medication?, , •, , Consider trauma: Is the person physically injured ?, , •, , Look for signs of infection: Redness and / or red, streaks around a wound., , •, , Look around for signs of poison: An empty bottle, of pills or a snake bite wound., , Symptoms of Shock, , •, , Consider the possibility of psychological trauma:, might the person have psychological disorder of some, sort?, , •, , Consider stroke, particularly for elderly people., , Victims appear pale, ice cold, pulse appear initially faster, and gets slower, breathing becomes shallow. Weakness,, dizziness, confusion continue. If unattended the patient, may become unconscious and die., , •, , Treat according to what you diagnose., , Shock (Fig 3), , As blood flow slows, so does the amount of oxygen, reaching the brain. The victim may appear to be, confused, week and dizzy and may eventually deteriorate, into unconsciousness. Try to compensate for this lack, of oxygen, the heart and breathing rates both speed up,, gradually becoming weaker, and may eventually cease., Potential causes of shock include: sever internal or, external bleeding: burns; severe vomiting and diarrohea,, especially in children and the elderly; problems with the, heart., , Shock kills, so it is vital that you can recognize these, signs and symptoms. With internal bleeding in particular,, shock can occur sometime after an accident, so if a, person with a history of injury starts to display these, symptoms coupled with any of the symptoms of internal, bleeding, advise them to seek urgent medical attention, or take or send them to hospital., First Aid, Keep the patient warm and at mental rest. Assure of, good air circulation and comfort. Call for help to shift the, patient to safer place / hospital., , A severe loss of body fluid will lead to a drop in blood, pressure. Eventually the blood’s circulation will, deteriorate and the remaining blood flow will be directed, to the vital organs such as the brain. Blood will therefore, be directed away from the outer area of the body, so the, victim will appear pale and the skin will feel ice cold., , •, , Warmth: Keep the victim warm but do not allow them, to get overheated. If you are outside, trytoget, something underneath her if you can do easily. Wrap, blankets and coats around her, paying particular, attention to the head, through which much body heat, is lost, , •, , Air: Maintain careful eye on the victim’s airway and, be prepared to turn them into the recovery position if, necessary, or even to resuscitate if breathing stops., Try to keep back by standers and loosen tight clothing, to allow maximum air to victim., , •, , Rest: Keep the victim still and preferably sitting or, lying down. If the victim is very giddy, lay them down, with there legs raised to ensure that maximum blood, and therefore maximum oxygen is sent to the brain., , Construction: Draughtsman Civil - (NSQF Level - 5): Related Theory for Exercise 2.7.81, , Copyright Free under CC BY Licence, , 189

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Electrical safety, Objective: At the end of this lesson you shall be able to, • explain how to rescue a person who is in contact with a live wire., The severity of an electric shock will depend on the leve, of current which passes through the body and the length, of time of contact. Do not delay, act at once. Make sure, that the electric current has been disconnected., , Electric burns on the victim may not cover a big area but, may be deep seatedd. All you can do is to cover the, area with a clean, sterile dressingand treat for shock., Get expert help as quickly as possible., , If the casualty is still in contact with the supply- break, the contact either by switching off the power, removing, the plug or wrenching the cable free. If not, stand on, some insulating material such as dry wood, rubber or, plastic, or using whatever is at hand to insulate yourself, and break the contact by pushing or pulling the person, free (Fig 1 & 2), , If the casualty is unconscious but is breathing, loosen, the clothing about the neck, chest and waist and place, the casualty in the recovery position. (Fig 3), , Keep a constant check on the breathing and pulse rare., Keep the casually warm and comfortable.(Fig 4), , Send for help., Do not give an unconscious person anything, by mouth., Do not leave an unconscious person attended., If you remain un-insulated, do not touch the victim with, your bare hands until the circuit is madee dead or person, is moved away from the equipment., , If the casualty is not breathing – Act at once – don’t waste, time., , If the victim is aloft, measures must be taken to prevent, him from falling or atleast make him fall safe., , 190, , Construction: Draughtsman Civil - (NSQF Level - 5): Related Theory for Exercise 2.7.81, , Copyright Free under CC BY Licence

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Safety practice - first aid, Objectives: At the end of this lesson you shall be able to, • explain how to treat a person affected due to electric shock/injury., Electric shock, The severity of an electric shock will depend on the level, of the current which passes through the body and the, length of time of the contract., Other factors that contribute to the severity of shock are:, – Age of the person, – Not wearing insulating footwear or wearing wet, footwear., – Weather condition, , Electrical burns:, , – Floor is wet or dry, , A person receiving an electric shock may also sustain, burns when the current passes through his body. Do, not waste time by applying first aid to the burns until, breathing has been restored and the patient can breathe, normally unaided., , – Mains voltage etc., Effects of electric shock, The effect of current at very low levels may only be an, unpleasant tingling sensation, but this by itself may be, sufficient to cause oe to loose his balance and fall., At higher levels of current, the person receiving the shock, may be thrown off his feet and will experience severe, pain, and possibly minor burns at the point of contract., At an excessive of level of current flow, the muscles, may contract and the person unable to release his grip, on the conductor. He may lose consciousness and the, muscles of the heart may contract spasmodically, (fibrillation). This may be fatal., Electric shock can also cause burning of the skin at the, point of contract., Treatment of electric shock, Prompt treatment is essential, , Burns and Scalds, Burns are very painful. If a large area of the body is, burnt, give no treatment, expect to exclude the air, e.g., by covering with water, clean paper, or a clean shirt. This, relieves the pain., Severe Bleeding, Any wound which is bleeding profusely, especially in the, wrist, hand or fingers must be considered serious and, must receive professional attention. As an immediate first, aid measure, pressure on the wound itself is the best, means of stopping the bleeding and avoiding infection., Immediate action: Always in cases of severe bleeding, •, , Make the patient lie down and rest, , •, , If possible, raise the injured part above the level of, the body (Fig 2), , •, , Apply pressure to the wound, , •, , Summon assistance., , If assistance is close at hand, send for medical aid, then, carry on with emergency treatment, If you are alone, proceed with treatment at once, Switch off the current, if this can be done without undue, delay. Otherwise, remove the victim from contract with, the live conductor, using dry non –conducting materials, such as a wooden bar, rope, a scarf, the victim’s coattails, any dry article of clothing, a belt, rolled-up, newspaper, non- metallic hose, PVC tubing, bakelised, paper, tube etc. (Fig 1), Avoid direct contact with the victim. Wrap your hands in, dry material if rubber gloves are not available., , Construction: Draughtsman Civil - (NSQF Level - 5): Related Theory for Exercise 2.7.81, , Copyright Free under CC BY Licence, , 191

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To Control severe bleeding, , Large wound, , Squeeze together sides of the wound. Apply pressure, as long as necessary to stop the bleeding. When the, bleeding has stopped, put a dressing over the wound,, and cover it with a pad of soft material (Fig 3), , Apply a clean pad (preferably an individual dressing) and, bandage firmly in place. If bleeding is very severe apply, more than one dressing (Fig 4)., , For an abdominal stab wound, such as may becaused, by falling on a sharp tool, keep the patient bending over, the wound to stop internal bleeding., , Follow the right methods of artificial respiration., , 192, , Construction: Draughtsman Civil - (NSQF Level - 5): Related Theory for Exercise 2.7.81, , Copyright Free under CC BY Licence

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Construction, Draughtsman Civil - Electrical wiring, , Related Theory for Exercise 2.7.82, , Elementary of electricity, Objectives: At the end of this lesson you shall be able to, • define atom and electricity, • explain about the atomic structure, • define conductors, insulator and semiconductors., Introduction, Electricity is one of today’s most useful sources of energy., Electricity is of utmost necessity in the modern world of, sophisticated equipment and machinery., Electricity in motion is called electric current. Whereas, the electricity that does not move is called static electricity., Example of Electric current, – Domestic electric supply, industrial electric supply., Example of static electricity, Shock received from door knobs of carpeted room., Attraction of paper to the comb., Structure of Matter, To understand electricity, one must understand the, structure of matter. Electricity is related to some of the, most basic building blocks of matter that are atoms, (electrons and portons). All matter is made of these, electrical building blocks, and therefore, all matter is said, to be ‘electrical’., , Protons, The proton has a positive electrical charge (Fig 1) It is, almost 1840 times heavier than the electron and it is the, permanent part of the nucleus; protons do not take an, active part in the flow or transfer of electrical energy., Electron, It is a small particle revolving round the nucleus of an, atom (as shown in Fig 2). It has a negative electric charge., The electron is three times larger in diameter than the, proton. In an atom the number of protons is equal to the, number of electrons., , Matter is defined as anything that has mass and occupies, space. A matter is made of tiny, invisible particles called, molecules. A molecule is the smallest particle of a, substance that has the properties of the substance. Each, molecule can be divided into simpler parts by chemical, means. The simplest parts of a molecule are called, atoms., Basically, an atom contains three types of sub-atomic, particles that are of relevance to electricity. They are the, electrons, portons and neutrons. The protons and, neutrons are located in the centre, or nucleus, of the atom,, and the electrons travel around the nucleus in orbits., Atomic Structure, The Nucleus, , Neutron, , The nucleus is the central part of the atom. It contains, the protons and neutrons of an atom as shown in Fig 1., , A neutron is actually a particle by itself, and is electrically, neutral. Since neutrons are electrically neutral, they are, not too important to the electrical nature of atoms., , 193, , Copyright Free under CC BY Licence

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Energy Shells, In an atom, electrons are arranged in shells around the, nucleus. A shell is an orbiting layer or energy level of one, or more electrons. The major shell layers are identified, by number or by letters starting with ‘K’ nearest the, nucleus and continuing alphabetically outwards. There, is a maximum number of electrons that can be contained, in each shell. Fig 3 illustrates the relationship between, the energy shell level and the maximum number of, electrons it can contain., , Atoms that are chemically active have one electron more, or one less than a completely filled shell. Atoms that have, the outer shell exactly filled are chemically inactive. They, are called inert elements. All inert elements are gases, and do not combine chemically with other elements., Metals possess the following characteristics, , If the total number of electrons for a given atom is known,, the placement of electrons in each shell can easily, determined. Each shell layer, beginning with the first, is, filld with the maximum number of electrons in sequence., For example, a copper atom which has 29 electrons would, have four shells with a number of electrons in each shell, as shown in fig. 4, , •, , They are good electric conductors., , •, , Electrons in the outer shell and sub-shells can move, more easily from one atom to another., , •, , They carry charge through the material., , The outer shell of the atom is called the valence shell, and its electrons are called valence electrons. Because, of their greater distance from the nucleus, and because, of the partial blocking of the electric field by electrons in, the inner shells, the attracting force exerted by nucleus, on the valence electrons is less. Therefore, valence, electrons can be set free most easily. Whenever a valence, electrons is moved from its orbit it becomes a free, electron. Electricity is commonly defined as the flow of, these free electrons through a conductor. Though, electrons flow from negative terminal to positive terminal,, the conventional current flow is assumed as from positive, to negative., Conductors, Insulators and Semiconductors, Conductors, A conductor is a material that has many free electrons, permitting electrons to move through it easily. Generally,, conductors have incomplete valence shells of one, two, or three electrons. Most metals are good conductors., , Similarly an aluminium atom which has 13 electrons has, 3 shells as shown in Fig 5., , Insulators, , Electron Distribution, The chemical and electrical behavior of atoms depends, on how completely the various shells and sub-shells are, filled., , 194, , Some common good conductors are Copper, Aluminum,, Zinc, Lead, Tin, Eureka, Nichrome, Silver and Gold., , An insulator is a material that has few, if nay, frees, electrons and resists the flow of electrons. Generally,, insulators have full valence shells of five, six or seven, electrons. Some common insulators are air glass, rubber,, plastic, paper, porcelain, PVC, fibre, mica etc., , Construction: Draughtsman Civil - (NSQF Level - 5): Related Theory for Exercise 2.7.82, , Copyright Free under CC BY Licence

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Semiconductors, A semiconductor is a material that has some of the, characteristics of both the conductor and insulator., Semiconductors have valence shells containing four, electrons., , Common examples of pure semiconductor materials are, silicon and germanium. Specially treated semiconductor, are used to produce modern electronic components such, as diodes, transistors and integrated circuit chips., , Wiring - Electrical, Objectives: At the end of this lesson you shall be able to, • explain the systems of wiring, • enlist the materials for wiring, • enlist the tools used dfor wiring, • explain the safety precautions., , Introduction, , Permanent wiring, , Electricity is a sort of energy which can neither be seen, nor touched but its presence can be experienced in its, applications like electric bulb, heater, motar or an electric, operated radio. Nowadays electricity is an unavoidable, operated radio. Nowadays electricity is an unavoidable, part of the life. We can’t imagine the world without, electricity. As a civil engineer we can make a lot of, involvement in the generation of electricity as well as its, distribution. In the least sense a new building is planned, in the economical and satisfactory wiring and, arrangements of fittings., , 1 Casing caping wiring (Fig 1), , Systems of Wiring, , 1 Temporary wiring, , 2 Permanent wiring, , a Flexible wire, wiring, , a Casing capping, wiring, , b Cleat wiring, , b CTS/ TRS wiring, , The system of wiring is being used for the last more than, 50 years, but is has become unpopular. The casing has, two grooves to carry wires., 2 CTS / TRS Wiring (Fig 2), , c Lead sheathed wiring, d Conduit pipe wiring, e Duct wiring, , Temporary wiring, 1 Flexible wire wiring, In this type of wiring flexible PVC wires are used. The, wiring may be utilized for one month or so. It is useful for, the decoration purposes in the marriage, exhibitions etc., A common main switch is used., , This type of wiring is installed on wooden battens, and, hence it is known as batten wiring also. Clips are used to, hold the wires., , 2 Cleat wiring, It is an open type wiring, which is done with VIR or PVC, wires. The wiring may be utilized for a year or so., Porcelain cleats are used to support the wires., , 3 Lead sheathed wiring, This system is similar to batten wiring but lead sheathed, wires are used instead of PVC wires. The lead covering, provides protection to cable against mechanical injuries., , Construction: Draughtsman Civil - (NSQF Level - 5): Related Theory for Exercise 2.7.82, , Copyright Free under CC BY Licence, , 195

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4 Conduit pipe wiring (Fig 3), , 5 Duct wiring (Fig 4), , This system of wiring is suitable for single or three face, wiring. The types of conuit pipes used area a) light gauge, conduit pipes. b) beavy gauge conduit pipe. VIR or PVC, wires are used for this wiring. This wiring is suitable for, factories, godowns, workshops etc., , It is also known as concealed wiring. For this wiring, grooves are made in the wall and floor as per diagram, and then conduit wiring is placed in the grooves. Finally, the wiring is covered with cement plaster. Only inspection, boxes, junction boxes, round blocks and switch boards, remain in visible outside the walls and ceiling., , Materials for Wiring, S .No., , Material, , Description, , 1, , Electrical Accessories, , It includes the switches, holders, sockets fuse, cut-outs, ceiling roses, etc., , 2, , Wires, , Generally VIR and PVC wires are used for wiring,, but TRS and weather proof wires are used as per, requirements., , 3, , Wooden Screws, , These are used for fixing the wooden boards, round, blocks, etc. on the wooden plugs. Their size varies, from 12 mm to 60 mm., , 4, , Porcelain and PVC pipes, , These pipes are water resistant. These are used, for passing the wiring across a wall or concealed, wiring, , 5, , Wooden boards and Plug, , The switches and sockets etc. are fitted on, rectangular boards of teak wood., , 6, , Distribution boards, , It comprises the fuse cut-out for different circuits., , 7, , Main switch boards, , It is fitted near the meter board. It includes main, switch, fuse cut-out, neutral link and earthing, terminals., , 8, , Meter board, , It is fitted by the electric distribution department. It, comprises an energy meter, fuse cut-out and, neutral link. The meter is sealed., , 196, , Construction: Draughtsman Civil - (NSQF Level - 5): Related Theory for Exercise 2.7.82, , Copyright Free under CC BY Licence

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Tools, S. No., , Name of tool, , Use, , 1, , Poker, , To make pilot holes in the boards, , 2, , Knife, , To remove insulators, , 3, , Nose pliers, , To hold wires in narrow place, screw and unscrew small, nuts, twist wires etc., , 4, , Adjustable pliers, , To hold sheets and other articles, , 5, , Combination pliers, , For gripping, bending and cutting wires, , 6, , Wrench, , To screw and unscrew, , 7, , Bench vice, , To hold tools, , 8, , Screw driver, , To tighten and untighten screws, , 9, , Cold chisel, , To make holes in masonry, , 10, , Wood chisel, , To cut slots in wooden boards, , 11, , Pipe vice, , To hold G.I. pipes, , 12, , Files, , To sharpen knife, , 13, , Taps, , To make threads, , 14, , Gauge, , To measure the thickness of wire, , 15, , Centre punch, , To make mark before drilling, , 16, , Plumb bob, , To make vertical lines on walls for wiring, , 17, , Key Hole screw, , To make key holes, cut wood along curves, , 18, , Tenon saw, , To cut wooden wiring material like battens, casing, etc., , 19, , Hand drilling machine, , To make holes, , 20, , Hammer, , For riveting, chipping. etc., , 21, , Ratchet brace, , To make large diameter holes in wood, , 22, , Stock and die, , To make threads on conduits and G.I. pipes, , 23, , Soldering iron, , To solder the joints of wires, , 24, , Neo tester, , To test the presence of electricity, , Construction: Draughtsman Civil - (NSQF Level - 5): Related Theory for Exercise 2.7.82, , Copyright Free under CC BY Licence, , 197

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Safety Precautions, 1 No live naked wire or electric gear etc. should be, touched because it will give electric shock., 2 Before working with the live wire, the supply should, be switched off., 3 Neither the live wire be touched with hand nor the, man working with the wire be touched., 4 Work on poles should not be done without using the, safety belt., 5 It should be ensured before switching on the supply, that no man is working with the wires., 6 No live wire should be earthed., 7 Before changing the fuse wire, the switch should be, turned in off position., 8 All the appliances should be properly earthed because, it ensures safety from electric shock., 9 No live wire should be without switches., 10 Plug from the socket should be removed by pulling, the wire but should be done carefully and correctly., 11 The earthing plate should be embedded in the most, earth at sufficient depth below ground level., 12 Water should never be thrown on the electric wires, and live conductors in case of fire. The line should be, first switched off and dry sand is used for extinguishing, the fire. Fire extinguisher may be used to put off the, fire., , 198, , Construction: Draughtsman Civil - (NSQF Level - 5): Related Theory for Exercise 2.7.82, , Copyright Free under CC BY Licence

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13 While the electric appliances like table fan, electric, iron, electric kettle or toaster are not in use, It is, advisable to pull out the plug instead of switching off, the switches, 14 Proper electrical tools should only be used for doing, jobs., , 15 It is advisable to check the earth resistance at least, once a year. If it is more than five ohms it should be, reduced immediately., 16 A first aid box should always be kept in the shop., 17 In case of any accident, the victim should be given, the facility of first and immediately before he is taken, to the doctor., , Trade hand tools - specification, Objectives: At the end of this lesson you shall be able to, • list the tools necessary for an electrician, • specify the tools and state the use of each tool, • explain the care and maintenance of electrician hand tools., It is important that the electrician uses proper tools for, his work. The accuracy of workmanship and speed of, work depend upon the use of correct tools. If the tools, are properly used, and maintained, the electrician will find, the working efficiency increases and the skills become a, work habit., Listed below are the most commonly used tools by, wireman., Their specifications and BIS number are given for your, reference. Proper method of care and maintenance will, result in prolonged tool life and improved working, efficiency., PLIERS, They are specified with their overall dimensions of length, in mm. The pliers used for electrical work will be of, insulated grip., , Flat nose pliers are used for holding flat objects like thin, plates etc., 3 Long nose pliers or (snip nose pliers) with side cutter, BIS.5658 (Fig 3), Size 100mm , 150 mm etc., , 1 Combination pliers with pipe grip, side cutter and, insulated handle. BIS 3650 (Fig 1), Size 150 mm, 200 mm etc., , Long nose pliers are used for holding small objects in, places where fingers cannot reach., 4 Side cutting pliers (Diagonal cutting pliers) BIS 4378, (Fig 4), Size 100 mm, 150 mm etc., , It is made of forged steel. It is used for cutting, twisting,, pulling, holding and gripping small jobs in wiring assembly, and repairing work. A non-insulated type is also avilable., Insulated piliers are used for work on live lines., 2 Flat nose pliers BIS 3552 (Fig 2), Size 100 mm, 150 mm, 200 mm etc., Construction: Draughtsman Civil - (NSQF Level - 5): Related Theory for Exercise 2.7.82, , Copyright Free under CC BY Licence, , 199

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It is used for cutting copper and aluminium wires of smaller, diameter (less than 4mm dia), 5 Round nose pliers BIS 3568 (Fig 5), Size 100mm, 150mm etc., , Screwdrivers are used for tightening or loosening screws., The screwdriver tip should snugly fir the grooves of the, screw to have maximum efficiency and to avoid damage, to the screw heads., As the length of the screw driver is proportional to the, turning force, for small work choose a suitable small sized, screwdriver and vice versa., Screwdriver – Philips, It is used for driving star headed screws., Care and maintenance, i, , Wire hooks and loops could be made using the round, nose pliers., Care and maintenance of pliers:, •, , Do not use pliers as hammers., , •, , Do not use pliers to cut large sized copper or, aluminium wires and hard steel wires of any size., , •, , While using the pliers avoid damages to the insulation, of hand grips., , •, , Lubricate hinged portions., , Never use a screwdriver as a lever to apply force as, this action will make the stem to bend and the use of, the screw driver will be lost., , ii Keep the tip in correct shape and in rare cases it could, be grinded to shape., 7 Neon tester BIS 5579 -1985 (Fig 7), , 6 Screwdriver BIS 844 (Fig 6), , It is specified with its working voltage range 100 to 250, volts but rated to 500 V., , The Screwdrivers used for electrical works generally have, plastic handles and the stem is covered with insulating, sleeves. The size of the screw driver is specified by its, blade length in mm and nominal screwdriver’s point size, (thickness of tip of blade) and by the diameter of the stem., E.g., , 75mm x 0.4 mm x 2.5 mm, 150mm x 0.6mm x 4 mm, 200mm x 0.8mm x 5.5 mm etc., , The handle of screwdrivers is either made of wood or, cellulose acetate., , 200, , It consists of a glass tube filled with neon gas, and, electrodes at the ends. To limit the current within 300, micro-amps at the maximum voltage, a high value, resistance is connected in series with one of the one end., The presence of supply is indicated by the glow of the, lamp when the tip like a probe or screwdriver at one end., The presence of supply is indicatedd by the glow of the, lamp when the tip is touched on the live supply and the, brass contact in the order of neon tester is touched by, hand., Care and maintenance, •, , Never use the neon tester for voltage higher than the, specified range., , •, , While testing see the circuit is completed through the, earthing o the body could be provided by touching the, wall by one hand., , Construction: Draughtsman Civil - (NSQF Level - 5): Related Theory for Exercise 2.7.82, , Copyright Free under CC BY Licence

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•, , Use the screwdriver tipped neon tester for light duty, work only., , 8 Electrician’s Knife (Double blade) (Fig 8), , Care and maintenance, i, , The size of the knife is specified by its largest blade length, e.g 50 mm, 75mm., , Do not use a hammer must be free from oil, grease, and mushroom., , ii The fce of the hammer must be free from oil, grease, and mushrooms., 11 Try-square: (Engineer’s square) (Fig 11) BIS 2103, , It is used for skinning the insulation of cables and cleaning, the wire surface. One of the baldes which is sharp is used, for skinning the cable and the rough edgedblade is used, for cleaning the surface of the wires., Care and maintenance, •, , Do not use the knife for cutting wires., , •, , Keep it free from rust., , •, , Keep one of the blades in a sharp condition., , •, , Fold the knife blade when not in use., , 9 Four-fild box wood rule 600mm (Fig 9), , This is specified by its blade length., E.g., , 5mm x 35mm, 100mm x 70mm, 100mm x 100mm etc., , Used for measuring short lengths. To be kept in folded, condition when not in use., 10 Hammer ball Pein (Fig 10), The size of the hammer is expressed in weight of the, metal head. Ex. 125 gms, 250 gms etc., , There are two types; one is the beveled edge with stock, and the other is the flat edge without stock. It is used to, check whether the object is plane, perpendicular and at, right angle. Two straight blades set at right angles to, each other constitute the try square. The steel blade is, riveted to the stock. The stock is made of cast iron. The, stock should be set against the edge of the job., Do not use it as s hammer, , The hammer is made out of special steel and the striking, face is tempered. Used for nailing, straightening, and, bending work. The handle is made of hard wood., , 12 Firmer Chisel (Fig 12), It has a wooden handle and a cast steel blade of 150mm, length. Its size is measured according to the width of the, , Construction: Draughtsman Civil - (NSQF Level - 5): Related Theory for Exercise 2.7.82, , Copyright Free under CC BY Licence, , 201

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blade eg. 6mm, 12mm, 18mm, 25mm. It is used for, chipping, scraping and grooving in wood., , 15 Files (Fig 15) BIS 1931, , Care and maintenance, Do not use it for driving screws., These are specified by their nominal length., , •, , Use mallet for chiseling, , •, , Grind on a water stone and sharpen on an oil stone., , Eg. 150 mm, 200 mm, 250 mm 300 mm etc., , •, , Do not use it in places where nails are driven., , These files have different numbers of teeth designed to, cut only in the forward stroke. They are available in, different lengths and sections (Ex. Flat, half round, round,, square, triangular), grades like rough, bastard second, cut and smooth and cuts like single and double cut., , 13 Tenon – saw (Fig 13) BIS 5123, BIS 5130, BIS 5031, , These files are used to remove fine chips of material from, metals. The body of the file is made of cast steel and, hardened except the tang., Care and maintainence, i, Generally the length of the tenon-saw will be 250 or 300, mm and has 8 to 12 teeth per 25.4 mm and the blade, width is 10 cm. It is used for cutting thin, wooden, accessories like wooden batten, casing capping, boards, and round blocks., , Never use the file as a hammer., , ii Do not use the file without the handle., iii Do not throw a file since the teeth get damaged., 16 Plumb bob (Fig 16), , Care and maintenance, •, , Keep free from rust., , •, , Apply grease when not in use., , 14 Wood rasp file (Fig 14) BIS 1931, It is used for filing wooden articles where finish is not, important. Wood rasp files are of half round shape. They, have sharp coarse single cut teeth., , 202, , Construction: Draughtsman Civil - (NSQF Level - 5): Related Theory for Exercise 2.7.82, , Copyright Free under CC BY Licence

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It has a pointed tip with a centre hole at the top for, attaching a string as shown in Fig 16. It is used for making, vertical lines on the wall., Care and Maintenance, Do not drop to the ground., 17 Bradawl square pointed (or poker) (Fig 17) BIS, 1035-1982, , It is used or making and punching pilot holes on metals., It is made of tool steel and the ends are hardened and, tempered., Care and Maintenance, •, , Keep the tip sharp and at a proper angle., , •, , Avoid mushroom heads., , 20 Mallet (Fig 20), , It is specified by its length and diameter eg. 150mm x, 6mm., It is a long sharp tool used for making pilot holes on, wooden articles to fix screws., Care and maintenance:, •, , Do not use it on metals for making holes., , •, , Keep it in good sharpened condition., , 18 Gimlet (Fig 18), , The mallet is specified by the diameter of the head or by, the weight., E.g.,, , 50 mm x 150 mm, 75 mm x 150 mm or 500 gms 1 kg, , It is made out of hard wood or nylon. It is used for driving, the firmer chisel, and for straightening and bending of, thin metallic sheets. Also it is used in motor assembly, work., It is used for boring small holes on wooden articles. It, has a wooden handle and a boring edge. The size of it, depends upon its diameter. Ex. 3mm, 4 mm, 5 mm, 6, mm, Care and maintenance, , Care and Maintenance, i, , Do not use it for fixing nail, , ii Never use it on hard metal like steel and iron, 1 Ratchet brace (Fig 21) BIS 7042, , •, , Do not use it without the handle., , •, , Do not use it on nails., , The size of a ratchet brace is given by the size of drill bit, it can accommodate ie. 0-6 mm, 0-12mm. It is used to, drill holes on wooden blocks., , •, , Keep it straight while making holes, otherwise the, screwed portion can get damaged., , 2 Flat cold chisel (Fig 22) BIS 402, , 19 Centre Punch (Fig 19) BIS 7177, , Its size is given by the nominal width and length., , The size is given by its length and diameter of the body., E.g. 100mm x 8 mm. The angle of the tip of the centre, punch is 90º., Construction: Draughtsman Civil - (NSQF Level - 5): Related Theory for Exercise 2.7.82, , Copyright Free under CC BY Licence, , 203

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Its size depends upon the number. As the number, increases, the thicknesses of the bit as well as the plug, also decrease. E.g. Nos.8, 10,12,14 etc., A rawl plug tool has two parts, namely the tool bit and tool, holder. The tool bit is made of tool steel and the holder is, made of mild steel. It is used for making holes in bricks,, concrete wall and ceiling. Rawl plugs are inserted in them, to fix accessories., Care and Maintenance, •, , Slightly rotate the holder after ech hammering stroke., , •, , Hold the tool straight., , •, , Do not throw it on the ground., , •, , Keep its head fee from mushrooms., , 24 Spanner: double ended (Fig 24) BIS 2028, , The size of a spanner is indicated so as to fit on the nuts., They are available in many sizes and shapes., ie. 14 mm x 100 mm, The sizes, indicated in double –ended spanners are:, 15mm x 150 mm, 10-11 mm, 20mm x 150mm, The body shape of a cold chisel may be round or hexagon., The cold chisel is made out of high carbon steel. Its cutting, edge angle varies from 35° to 45° . The cutting edge of, the chisel is hardened and tempered. This chisel is used, for making holes on wall etc., , 12-13 mm, 14-15 mm, 16-17 mm, 18-19 mm, 20-22 mm, , − The edge of a chisel must be maintained as per the, , For loosening and tightening of nuts and bolts, spanner, sets are used. It is made out of cast steel. They are, available in many sizes and may have single or double, ends., , − While grinding a chisel apply a coolant frequently so, , 25 Ring spanner set (Fig 25) BIS 2029, , Care and Maintenance, required angle., , that its temper may not be lost., , 23 Rawl plug tool and bit (Fig 23), , 204, , Construction: Draughtsman Civil - (NSQF Level - 5): Related Theory for Exercise 2.7.82, , Copyright Free under CC BY Licence

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The ring spanner is used in places where the space is, restricted and where high leverage is required., , The size will be the maximum length it can measure., E.g. Blade 12 mm wide 2 metres long., , 26 Socket (box) Spanner (Fig 26) BIS 7993, 7991, 6129, The measuring tape is made of thin steel blade, bearing, dimensions on it., It is used for measuring the dimension of the wiring, installation and general measurements., Care and maintenance, •, , Handle with great care as carelessness may spoil the, graduation., , 29 Hacksaw (Fig 29) BIS 5169 – 1986 for frames, BIS 2594 – 1977 for blades, These spanners are useful at places where the nut or, bolt is located in narrow space or at depth., 27 Single ended open jaw adjustable spanner, (Fig 27) BIS 6149, , It saves time and working. The movable jaw is made, adjustable by operating a screw. It is known as a monkey, wrench also. Available in 150,200,250 mm etc., Care and maintenance, •, , Use correct size spanner suitable to the size of nut, and bolt., , •, , Do not use a spanner as a hammer., , •, , While using a spanner do not strike it with a hammer.., , •, , Prevent the grease and oil traces on its jaws., , 28 Measuring Steel tape (Fig 28), , It is made out of sturdy nickel plated steel frame. The, frame can be adjusted for 250 mm to 300 mm blades. It, should be fixed on the frame with its teeth pointing away, from the handle in order to do the cutting in forward stroke., It is mainly used for cutting metals., Care and maintenance, •, , The blade should be properly tightened., , •, , Use a coolant while cutting., , •, , It should be straight during cutting., , •, , Lift the saw slightly on the return stroke., , •, , Do not attempt to saw too fast., , 30 Pincers (Fig 30) BIS 4195, , Construction: Draughtsman Civil - (NSQF Level - 5): Related Theory for Exercise 2.7.82, , Copyright Free under CC BY Licence, , 205

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The Size is given by its length. E.g. 100 mm, 150mm,, 200 mm., , 32 Portable Electric Drilling Machine (Fig 32), , It is used for extracting nails from the wood., Care and maintenance, •, , Do not use it as a hammer., , 31 Hand drill (Fig 31), , When power is available, a power drilling machine is a, more convenient and accurate tool for drilling holes on, wooden and metal articles., Care and maintenance, , The size is given by the twist drill bits which can be fitted, in e.g 6 mm , 0-12 mm capacity., A hand drill machine is used for making holes in thin metal, sheets or wooden articles., , •, , Lubricate all the moving parts of the machine., , •, , Fix the drill bit firmly in the jaws., , •, , Before drilling mark the job with a centre punch., , •, , For taking out the drill bit move the chuck in the reverse, direction., , •, , Do not apply excess pressure on small bits., , •, , In the case of an electric drilling machine it must be, properly earthed and the insulation should be sound., , Domestic wiring installation, Objectives: At the end of this lesson you shall be able to, • explain the necessity of inspection and test for a domestic wiring installation and the items to be inspected, • explain the type of test to be carried out in wiring installations and their necessity, • explain the procedure of conducting the following tests:, – continuity test, – effectiveness of eaarth connection, – insulation test between conductors, – insulation test between conductors and earth, – polarity, • explain the necessity of installing correct rating fuses in a circuit taking into consideration the connected, load and the circuit cable capacity., General requirement of inspection and tests (Ref:, BIS 732 – (Part III) 1982), Before a completed installation, or an addition to the, existing installation, is put into service, inspection and, existing shall be carried out in accordance with the Indian, Electricity Rules, 1956. In the event of defects being, found, these shall be rectified, as soon as practicable, and the installation retested., 206, , Periodic inspection and testing shall be carried out in order, to maintain the installation in a sound condition after, putting it into service., Where an addition is to be made to the fixed wiring of an, existing installation. The latter shall be examined for, compliance with the recommendations of this code., , Construction: Draughtsman Civil - (NSQF Level - 5): Related Theory for Exercise 2.7.82, , Copyright Free under CC BY Licence

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The individual equipment and materials which form part, of the installation shall generally conform to the relevant, Indian Standard specification wherever applicable. If there, is no relevant Indian Standard specifications for any item,, these shall be approved by the appropriate authority., Specification of the installation, On Completion of wiring a general inspection shall be, carried out by competent personnel in order to verify that, the provisions of this code and those of Indian Electricity, Rules, 1956 have been complied with. This, among other, things, shall include checking whether all equipments,, fittings, accessories, wires/cables, usedd in the installation, are of adeequate rating and quaality to meet the, requirement of the load; the layout and finish shall be, examined for neatness that would facilitate easy, identification of circuits of the system, adequacy of, clearancees, soundness of the termination with respect, of tightness, contact pressure and contact area. A, complete check shall also be made of all the protective, devices, with respect to their ratings, range of settings, and coordination between the various protective devices., Items to be inspected in lighting circuit, Lighting Circuits – The lighting circuits shall be checked, for the following., 1 Wooden boxes and panels are avoided in factories, for mounting the lighting boards and switch controls, etc., 2 Neutral links are provided in double- pole switch-fuses, which are used for lighting control and no fuse is, provided in the neutral., 3 The plug points in the lighting circuit are all 3-pin type,, the third pin being suitably earthed., 4 Tamper – proof interlocked switch socket and plugs, are used for locations easily accessible., 5 Lighting wiring in factory area is taken in enclosed, conduit and the conduit properly earthed, or, alternatively, armoured cable wiring is used., 6 A separate earth wire is run in the lighting installation, to provide earthing for plug points, fixtures and, equipments., 7 Proper connectors and junction boxes are used, wherever joints are to be made in conductors or cross, over of conductors takes place., 8 Cartridge fuse units are fitted with cartridge fuses only., 9 Clear and permanent identification marks are painted, in all distribution boards, switchboards, sub-main, boards and switches as necessary., 10 The polarity having been checked and all fuses and, single –pole switches are connected on the phase, conductor only and wiring is correctly connected to, socket-outlets., , 11 Spare knock-outs provided in distribution boards and, switch fuses are blocked., 12 The ends of conduits enclosing the wiring leads are, provided with ebonite or other suitable bushes., 13 The fittings and fixtures used for outdoor use are all, of whether – proof construction, and similarly, fixtures,, fittings and switchgears used din the hazardous area, are of flame-proof application., 14 Proper terminal connectors are used for termination, of wires (conductors and earth leads) and all strands, are inserted in the terminals;, 15 Flat ended screws are used for fixing conductors to, the accessories., 16 Use of flat washers backed up by spring washer for, making end connections is desirable and executed., 17 The number of wires in a conduit conforms to, provisions of Part II of BIS 732., Testing of Installation, After inspection, the following tests shall be carried out,, before an installation or an addition to the existing, installation is put into service. Any testing of the electrical, installation shall commerce after obtaining a permit to, work from the engineer-in-charge and after ensuring the, safety provisions., A test should be conduct with an insulation tester whose, rated DC voltage is double the working volatage of the, installations provided that it need not exceed 500 v for, medium voltage circuit., 1 Continuity or open ciruit test., 2 Effectiveness of earth connections., 3 Insulation test, •, , Between conductors, , •, , Between conductors and earth, , 4 Polarity test., Continuity or open circuit test, This is test is carried out to check the continuity of cables, in the individual sub-circuits. Before conducting this test,, the main and all distribution circuit fuse should be, removed., The phase and neutral of the individual circuits should be, identified from the distribution board and segregated., Place all bulbs in position, connect fans to the respective, ceiling roses, regulators and switches, short all socket, outlets by linking phase and neutral., Connect the megger terminals E and L to the individual, circuit phase nd neutral as shown in Fig 1; rotate the, megger., , Construction: Draughtsman Civil - (NSQF Level - 5): Related Theory for Exercise 2.7.82, , Copyright Free under CC BY Licence, , 207

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Megger is suitable) The Megger terminals should be, connected between earth and the whole system of, conductor or any section thereof with all fuses in place, and all switches closed, and except in earthed, concentric wiring, all lamps in position or both poles, of installation. Otherwise electrically connected, together, a DC voltage, of not less than twice the, working voltage provided that it does not exceed 500, volts for medium voltage circuits. Where the supply is, derived from three-wire (AC or DC) or poly-phase, system, the neutral pole of which is connected to earth, either direct or through added resistance, the working, voltage shall be deemed to be that which is maintained, between the outer or phase conductor and the neutral., b The insulation resistance in megohms of an installation, measured as in (a) shall not be less than 50 divided, by the number of points on the circuit, provided that, the whole installation need not be required to have, an insulation resistance greater than one megohm., By switching ‘ON’ and ‘Off’ the switches one by one, the, Megger should show zero reading and infinity alternatively., Two-way switches may have to be operated alternatively, to ensure the correct test results., If the Megger shows no continuity in the ‘ON’ condition of, the switch, then the particular circuit is deemed to be open., On the other hand, if the Megger shows continuity in both, the ‘ON’ and ‘OFF’ positions of the switch, it indicates, short in the particular circuit., Remember to remove all the shorting links at the socket, points and to connect phase to the fuse, and neutral to, the link , before switching ‘ON’ the supply., Testing the effectiveness of earth connection, For checking the efficiency of the earthing the following, tests are done., a Testing the continuity of earth continuity conductor, (ECC) and measuring its resistance., The earth continuity conductor resistance, value should not be higher than 1 Ohm., b The earth resistance of electrode shall be measured., The value of earth electrode resistance should not, exceed 5 ohms or a value such that the protective, devices in the circuit efficiently operate in the case of, earth faults in the circuit., , c Control rheostats, heating and power appliances and, electric signs, may , If desired , be disconnected from, the circuit during the test, but in that event the insulation, resistance between the case or framework, and all, live parts of each rheostat, appliance and sign shall, be not less that specified in the relevant Indian, Standard specification, or where there is no such, specification, shall be not less half a megohm., d The insulation resistance shall also be measured, between all conductors connected to one pole or, phase conductor of the supply and all the conductors, connected to the middle wire to the neutral on to the, other pole of phase conductors of the supply. Such a, test shall be made after removing all metallic, connections between the two poles of the installation, and in these circumstances the insulation resistance, between conductors of the installation shall be not less, than that specified in (b)., On completion of an electrical installation (or an extension to an installation) a certificate shall be furnished by, the contractor, counter-signed by the authorised supervisor under whose direct supervision the installation was, carried out. This certificate shall be in the prescribed, form as required by the local electric supply authority., Insulation resistance between conductors, For this test, switch off the mains and remove the fuse, carriers., Remove all lamps from their holders, disconnect all appliances, keep all switches in ON position., , Insulation test in wiring installation (Ref: BIS732 Part, II- 1982):, , Keep all the distribution fuses in position., , The following tests shall be done:, , Connect one test prod of the Megger to the phase cable, and the other to neutral as shown in Fig 2., , a The insulation resistance shall be measured by an, insulation tester/Megger having a voltage rating twice, the system voltage (for medium voltage systems 500, 208, , Construction: Draughtsman Civil - (NSQF Level - 5): Related Theory for Exercise 2.7.82, , Copyright Free under CC BY Licence

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where the switch, lamp-holder and socket are taken as, individual points., METHOD 2, IE rules states that the leakage current in an installation should not exceed 1/5000th part of the full load, current of the installation., Applying this, the value of insulation resistance, =, , Rotate the Megger and measure the insulation resistance, in megohms., , since leakage current, , The reading in megohms should not be less than the, lowest of the reading obtained in any one of the three, methods stated under insulation resistance between, conductors and earth., Insulation resistance between conductors and earth, For this test, put ‘OFF’ the main switch and remove the, main fuse carrier. All distribution fuses should be ‘IN’ ,, lamps should be in their holders and all switches for fan, and light should be in the ‘IN’ position. Unplug all the, appliances from the socket and short the phase and, neutral of sockets with a jumper wire., Connect the phase and neutral cables at the outgoing, terminals of the main switch together and connect the, lead of the Megger terminal to this shorted cable as shown, in Fig 3. Connect the other lead of the Megger to the, earth connection and rotate the Megger at its rated speed., , Supply voltage in Volts, Ω, Leakage Current, , =, , Supply voltage in Volts, Ω, Leakage Current, , =, , Full load current of installation, 5000, , =, , Supply voltage in volts x 5000, Ω, Full load current of the installation, , =, , Supply voltage in volts x 5000 x 10−6, mΩ, Full load current of installation, , METHOD 3 Thumb rule, The measured insulation resistance of an, installation should not be less than one, megohm., Polarity test, This test is conducted to check whether switches are, connected in phase/live cable or not., For conducting this test the lamps are removed from the, lamp- holders, the fan regulators are kept in the ‘OFF’, position and the fuses in the main and distribution boards, are inserted., Remove the switch covers and switch ‘ON’ the supply., Connect one end of the test lamp to the earth continuity, conductor and the other end of the test lamp to the switch, terminals alternatively as shown in Fig 4., , The reading thus obtained should not be lower than the, lowest of the values obtained in the following three, methods., METHOD 1 Standard value as per B I S, Standard value of, 50, mΩ, =, insulation, No. of points in the circuit, resistance, , Lighting of the test lamp indicates that the phase or live, cable is controlled by the switch., Further polarity test should be done on the sockets to, verify whether, •, , the phase wire is connected to the right side hole of, the socket as shown in Fig 5, , •, , the switch controls the phase wire., , Construction: Draughtsman Civil - (NSQF Level - 5): Related Theory for Exercise 2.7.82, , Copyright Free under CC BY Licence, , 209

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For this test, the neon tester could be inserted in the right, side hole of the socket as shown in Fig 5 and the control, switch is switched ‘ON’. Lighting of the neon tester, when the switch is ‘ON’ and no light when the switch is, ‘OFF’ indicates correct polarity. This test is a must in all, old or new wiring installations as a safety measure., Necessity of correct rating fuse in a circuit, The prime use of a fuse in a circuit is to protect the circuit, from excess current. The reasons for excess current in, a circuit may be overload, earth fault or short circuit. In, such cases of current more than normal, the fuse melts, and opens the circuit., The fuse rating is normally decided by the load or by the, capacity of the circuit cable whichever has a lower rating., If the load requires 10 amps and the cable capacity is, only 5 amps, then the fuse should be restricted to 5 amps, only. On the other hand such a situation is practically, impossible as the fuse will blow soon after the load is, switched on. On the contrary if a 10 amps fuse is placed, in the circuit, the under-rated cables will get overheated, and cause fire hazards., But in a circuit, there is a possibility that the circuit cables, may be of a higher capacity but the connected load may, be less than the cable capacity. In such cases, it is, advisable to use a fuse of the load rating. In the event of, earth fault or short circuit, the fuse will blow and open the, circuit eliminating chances of shock or fire hazards in the, equipment. On the other hand in the above case, the, fuse rated for the cable capacity will end in shock or fire, hazard., Hence, it is utmost necessary to place the correct capacity fuse in the circuit. As rewirable fuses cannot be readily, identified, in case of doubt, it is better to replace the, correct fuse wires taken from well marked stock., , 210, , Construction: Draughtsman Civil - (NSQF Level - 5): Related Theory for Exercise 2.7.82, , Copyright Free under CC BY Licence

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Inspection and testing of wiring installations - Method of improving test results, - IE Regulations, Objectives: At the end of this lesson you shall be able to, • determine the condition of installation according to test results and the method of improving the condition, • state I E regulations pertaining to testing of wiring installations., The Table given below shows the test results and methods to improve the conditions of wiring installations., Test result table and methods for improving conditions, Sl.No., 1, , Test conducted, Continuity test, , Method of improvement, , Test result, a. Zero reading, , O. K., , b. Higher reading in terms of kiloohms Operate each individual switch in the circuit, where the reading jumps to a higher value., or megaohms, There will be open circuit either by fused bulbs or, loose connections at the terminals or break in, wire. After identifying the sub-circuit, check the, continuity of cables in smaller zones till the, defect is detected and rectified. Where 2-way, switches are encountered, operate the switches, one by one to detect the fault., 2, , Polarity test, , a. Polarity was found wrong through Switch off the mains, remove the fuse carrier., installaiton., Inter-change the output terminals at C D P switch, or at D B., b. Polarity found wrong in one or two, See that the phase is connected to the right side, sockets, terminal of the socket., , 3, , Effectiveness of a. Discontinuity between earth elec- Check up the connections and reconnect or, trode and one earth pin or 3-pin replace earth connection the earth continuity, earth connection, socket, conductor., Earth electrode resistance may be high E C C, b. Indicates voltage drop between (Earth continuity Conductor) resistance. Prepare, phase and metallic body when one more earth electrode and connect the, tested by the test lamp method, electrodes in parallel., Remove rust and loose connections in the E C C, connections at all the earth terminals, including, the one at the earth electrode., , 4, , Insulation test be- a. I mega Ohm or above, tween conductors, and earth or be- b. Less than 1 mega Ohm, tween conductors., , OK, Check the value of insulation resistance by the, formula, Mega Ohms =, , 50, No. of Outlets, , In case the measured value of insulation resistance is equal or more than the calculated value, the insulation is OK. Otherwise locate the fault by, sectionalising the zone and replace the defective, cable. If the fault does not lie in one section,, proceed to the distribution board and test each, branch circuit until the faulty circuit or circuits are, discovered, Construction: Draughtsman Civil - (NSQF Level - 5): Related Theory for Exercise 2.7.82, , Copyright Free under CC BY Licence, , 211

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I.E. Regulations, 1 A new installation must be inspected and tested before, connecting it to the main supply., 2 The circuit under test must be isolated or disconnected, from the supply., 3 The use of a neon (tester) indicator is not reliable for, the use of polarity testing. Hence, a proper polarity, test using Megger should be conducted., 4 The resistance of the earth continuity conductors should, not be more than 1 ohm, in medium voltage domestic, installations., , 5 In the case of medium voltage domestic installations,, the insulation resistance between the conductor and, the earth must be more than one megohm., 6 In the case of medium voltage domestic installations,, the insulation resistance between any two conductors, must be more than one megohm., 7 A domestic wiring installation shall be tested on completion with a direct current pressure of not less than, twice the working pressure., , Diagrams and systems used in domestic installation, Objectives: At the end of this lesson you shall be able to, • identify a layout, installation plan, circuit diagram and wiring diagram and their uses, • identify the B I S symbols used in electrical layout drawings., In electrical wiring work, the Electrician/Wireman is supplied with a layout of wiring installation and an installation, plan initially., , The layout diagram shown in Fig 1 is the simplified version, of the wiring diagram. Its purpose is to inform the reader, quickly and exactly what the circuit is designed for without, giving any information on the circuit itself., , On the basis of the layout and installation plan, the electrician/wireman should draw the circuit and wiring, diagrams before the commencement of work for a systematic execution of the work., , This type of layout diagrams is used for preparing architectural diagrams, plans, etc. of a building., , The terms used in wiring installation drawings are explained here., , In layout diagrams, it is necessary to indicate with symbols the details like wiring on surface or concealed, cable, run ‘up’ or ‘down’, number of wires in the run, dimensions, and accessories with appropriate I S symbols., , 1 Layout diagram, Normally the layout plan is drawn and then the wiring, diagram is drawn. After completion of the wiring diagram, the number of cables to be run in each cable run and the, size of the conduit or batten are estimated. With the help, of the distance marking in the layout plan, the estimation, of cables, could be made., , 2 Installation diagram, 3 Circuit diagram, 4 Wiring diagram, Layout diagram (Fig 1), , Installation plan (Fig 2), This shows the physical position of accessories in an installation and also gives the final appearance of the, installation. It may not be possible to draw the installation, plan for the entire layout diagram. But it can be restricted, to a small part of the installation to highlight the type of, conduit, accessories, spacing of gutties, clamps etc., Circuit diagram (Fig 3), Refer to Fig 3. This shows the schematic connections of, the circuit for a specific task in the most simple form, incorporating the graphical symbols., Some customers give their requirement in writing. But, some can give in the form of a layout diagram to the, electrician/wireman. In the case of a written requirement, the electrician/wireman will prepare a layout diagram and, then get the approval of the consumer., , 212, , The purpose of the circuit diagram is to explain the, function of the various accessories in the circuit. Fig 3 is, an example of a circuit diagram for controlling a lamp, from two different places., , Construction: Draughtsman Civil - (NSQF Level - 5): Related Theory for Exercise 2.7.82, , Copyright Free under CC BY Licence

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Wiring diagram (Fig 4), , This is the diagram in which the position of the, components in the diagram bears a resemblance to the, actual physical position., The wiring diagram may not have distance marking. Use, of the wiring diagram along with the layout diagram, enables the technician in the initial stage of planning to, specify/estimate the required type, size and length of the, cables and also for deciding vertical, horizontal and ceiling, runs of the cable. This wiring diagram is of great use to, test and rectify faults in the installation during maintenance, work. Fig 4 shows the wiring diagram of controlling a lamp, from two different places with their actual locations., For his own good and to facilitate quick location of faults, at a later time, the customer should insist on the, electrician/wireman to give one copy of the wiring diagram, soon after the completion of wiring. The electrician/, wireman should make it a point to do so., , BIS Regulations, recommendations and NE code pertaining to wiring, installations, Objectives: At the end of this lesson you shall able to, • state the B I S recommendations and National Electrical Code pertaining to electrical installations, • state the B I S regulations and recommendations of the National Electrical Code of practice with regard to, the mounting level of switches, sockets, distribution boards and cable runs etc., The wiring installation shall generally be carried out in, conformity with the requirements of the Indian Electricity, Act 1910 as updated from time to time and the Indian, Electricity Rules 1956, framed thereunder and also the, relevant regulations of the Electric Supply authority of the, concerned area (State Government)., To govern the installation of electrical wirings in buildings,, with particular reference to safety and good engineering, practice, the Indian Standard is published., The following are some of the extracts of B.I.S. (Bureau, of Indian Standards) regulations pertaining to wiring installations. All the B.I.S. regulations are recommended, by the National Electrical Code (NEC)., , B I S regulations pertaining wiring installations, Wiring, Any one of the following types of wiring may be used in a, residential building., a Tough rubber sheathed (TRS) or PVC sheathed or, batten wiring., b Metal sheathed wiring system, c, , Conduit wiring system, i, , Rigid steel conduit wiring, , ii Rigid non-metallic conduit wiring (PVC), iii PVC casing and capping, , Construction: Draughtsman Civil - (NSQF Level - 5): Related Theory for Exercise 2.7.82, , Copyright Free under CC BY Licence, , 213

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Fittings and accessories, All fittings, accessories and appliances used in wiring installation shall conform to Indian Standards (I S mark)., The system should provide ease of access to fittings for, maintenance and repair and for any possible modification, to the system. Modifications to the system shall be done, only by licensed electrical contractors, licensed under the, Indian Electricity Rules., Sub-circuits - different types, The sub-circuits may be divided into the following two, groups., , •, , Light and fan sub-circuit,, , •, , Power sub-circuit, , After the main switch, the supply shall be brought to a, distribution board. Separate distribution boards shall be, used for light and power circuits., Light and fan sub-circuit, Lights and fans may be wired on a common circuit. Each, sub-circuit shall not have more than a total of ten points, of lights, fans and 6A socket-outlets. The load on each, sub-circuit shall be restricted to 800 watts. If a separate, circuit is installed for fans, the number of fans in that circuit, shall not exceed ten., , Simple electrical circuit and its elements, Objectives: At the end of this lesson you shall be able to, • describe a simple electric circuit, • explain the current , its units and method of measurement (Ammeter), • explan the emf, potential difference, their units and method of measurement (Voltmeter), • explain resistance and its unit, and quality of electricity., and a protection device (fuse) to interrupt the circuit in, case of malfunction of the circuit (excess current)., , Simple electric circuit, A simple electrical circuit is one in which the current flows, from the source to a load and reaches back the source, to complete the path., As shown in Fig 1, the electrial circuit should consist of, the following., , •, , An energy source (cell) to provie the voltage needed, to force the current through the circuit., , •, , Conductors through which the current can flow., , •, , A load (resistor) to control the amount of current and, to convert the electrical energy to other forms., , •, , A control device (switch) to start or stop the flow of, current., , In addition to the above, the circuit may have insulators, (PVC or rubber) to confine the current to the desired path,, , 214, , Electric Current, Fig 2 shows a simple circuit which consists of a battery, as the energy source and a lamp as the resistance. In, this circuit, when the switch is closed, the lamp glows, because of the electric current flows from the +ve terminal, of the source (battery) via the lamp and reaches back, the –ve terminal of the source., , Flow of electric current is nothing but the flow of electrons., Actually the electrons flow is from the negative terminal, of the battery to the lamp and reaches back to the positive, terminal of the battery., However direction of current flow is taken conventionally, from the +ve terminal of the battery to the lamp and back, to the –ve terminal of the battery. Hece, we can conlude, the conventional flow of current is opposite to the direction, of the flow of electrons. Through out the Trade Theory, book, the current flow is taken from the +ve terminal of, source to the load and then back to the –ve terminal of, the source., , Construction: Draughtsman Civil - (NSQF Level - 5): Related Theory for Exercise 2.7.82, , Copyright Free under CC BY Licence

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Ampere, The unit of current (abbreviated as I) is an ampere, (symbol A). If 6.24 x 1018 electrons pass through a, conductor per second, then we can say one ampere, current has passed through the conductor., Ammeter, We know the electrons cannot be seen and no human, being can count the electrons. As such an instrument, called ammeter is used to measure the current in a circuit., As an ammeter measures the flow of current in amperes it, should be connected in series with the resistance (Load) as, shown in Fig 3. For the decimal and decimal sub-multiples, of the ampere we use the following expressions., , The difference in the distribution of electrons between, the two terminals of the battery produces this emf., Potential difference (PD), The unit of electromotive force is the volt (symbol V) and, the emf is commonly referred as ‘voltage’. When the, battery is connected to any load, the voltage measured, across the terminals is called potential difference (PD), and this will be slightly less than the value of emf., Voltmeter, Electrical voltage is measured with a voltmeter. In order, to measure the voltage of a source, the terminals of the, voltmeter must be connected to the terminals of the, source. Positive to the positive terminal and negative to, the negative terminal, as shown in Fig 4. The voltmeter, connection is across or it is a parallel connection., , 1 kilo-ampere = 1 kA = 1000 A = 1 x 103A, 1 milli-ampere = 1 mA = 1/1000 A = 1 x 10–3A, , For the decimal or decimal sub-multiples of the volt, we, use the following expressions., , 1 micro-ampere = 1μA = 1/1000000 A = 1 x 10–6A, 1 kilo-volt, , = 1 kV = 1000 V, , Electromotive force, = 1 x 103V, In order to move the electrons in a circuit- that is to make, the current to flow, a source of electrical energy is, required. In a torch light, the battery is the source of, electrical energy., , 1 milli-volt, , = 1 mV = 1/1000 V, = 1 x 10–3V, , The terminals of the battery are indicated in the circuit, symbol by two lines, the longer line for the positive and, the shorter for the negative terminal., , 1 micro-volt = 1 μV = 1/1000000, , Within the battery the negative terminal contains an, excess of electrons whereas the positive terminal has a, deficit of electrons. The battery is said to have an, electromotive force (emf) which is available to drive the, free electrons in the closed path of the electrical circuit., , Resistance, , V = 1 x 10–6V, , In addition to the current and voltage there is a third quantity which plays a role in a circuit, called the electrical, , Construction: Draughtsman Civil - (NSQF Level - 5): Related Theory for Exercise 2.7.82, , Copyright Free under CC BY Licence, , 215

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resistance. Resistance is the property of a material by, which it opposes the flow of electric current., Ohm, The unit of electrical resistance (abbreviated as R) is ohm, (symbol W)., , Internation Volt, It is defined as that potential difference which when, applied to a conductor whose resistance is one, international ohm produces a current of one international, ampere. Its value is equal to 1.00049V., Conductance, , For the decimal multiples or decimal sub-multiples of the, ohm we use the following expressions:, 1 megohm, , = 1 MΩ = 1000000Ω, , = 1 x 106Ω, , 1 kilo-ohm, , = 1 kΩ = 1000Ω, , = 1 x 103Ω, , 1 milli-ohm, , = 1 mΩ = 1/1000Ω, , = 1 x 10–3Ω, , 1 micro-ohm, , = 1 μΩ = 1/1000000Ω = 1 x 10–6Ω, , Meter to measure resistance, Ohmic value of a medium resistance is measured by an, ohmmeter or a Wheatstone bridge. (Fig 5) There is a, provision to measure the ohmic value of a resistance in a, multimeter. There are various methods to determine the, ohmic value of resistance. Some of these methods will, be explained later in this book., , The property of a conductor which conducts the flow of, current through it is called conductance. In other words,, conductance is the reciprocal of resistance. Its symbol is, G (G = 1/R) and its unit is mho represented by . . Good, conductors have large conductances and insulators have, small conductances. Thus if a wire has a resistance of R, Ω, its conductance will be 1/R, Electro motive force (emf), The force which causes current to flow in the circuit is, called emf. Its symbol is E and is measured in volts (V). It, can be calculated as, emf = voltage at the terminal of source of supply +, voltage drop in the source of supply, or emf = VT + 1R, Terminal Voltage, It is the voltage available at the terminal of the source of, supply. Its symbol is VT. Its unit is also the volt and is also, measured by a voltmeter. It is given by the emf minus the, voltage drop in the source of supply, i.e., VT = emf - IR, where I is the current and R is the resistance., Quantity of electricity, As the current is measured in terms of the rate of flow of, electricity, another unit is necessary to denote the quantity, of electricity (Q) passing through any part of the circuit in, a certain time. This unit is called the coulomb (C). It is, denoted by the letter Q. Thus, Quantity of electricity = current in amperes, x time in seconds, , International Ohm, It is defined as that resistance offered to an unvarying, current (DC) by a column of mercury at the temperature, of melting ice (i.e. 0°C), 14.4521 g in mass, of constant, cross-sectional area (1 sq. mm) and 106.3 cm in length., International Ampere, One international ampere may be defined as that, unvarying current (DC) which when passed through a, solution of silver nitrate in water, deposits silver at the, rate of 1.118 mg per second at the cathode., 216, , or, , Q = I x TC, , Coulomb, It is the quantity of electricity transferred by a current of, one ampere in one second. Another name for the above, unit is the ampere-second. A larger unit of the quantity of, electricity is the ampere-hour (A.h) and is obtained when, the time unit is in hours, 1 A.h = 3600 A.s or 3600 C, , Construction: Draughtsman Civil - (NSQF Level - 5): Related Theory for Exercise 2.7.82, , Copyright Free under CC BY Licence

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Types of electrical supply, Objectives: At the end of this lesson you shall be able to, • explain the different types of electrical supply, • differentiate between alternating current and direct current, • differentiate between alternating voltage and direct voltage, and their sources, • identify AC and DC supply by the terminal markings., Working with electricity requires making accurate, measurements. Measurements are done by using, instruments (meters)., There are various types of instruments working on, different principles. Each instrument is designed to, measure a particular electrical quantity or more than one, quantity with suitable modification and necessary, instruction. Further they may be designed to measure, AC or DC supply quantities or can be used in either supply., To enable proper use of the instruments, the wireman, should be able to identify the type of supply with the help, of the details given below., Type of electrical supply (Voltage), There are two types of electrical supply in use for various, technical requirements. The alternating current supply, (AC) and the direct current supply (DC)., , –, , DC is represented by this symbol., , ~, , AC is represented by this symbol., , DC Supply, The most common sources of DC supply are the cells/, batteries (Figs 1a and 1b) and DC generators (dynamos)., (Fig 1C), , Direct voltage is of constant magnitude (amplitude). It, remains at the same amplitude from the moment of, switching on to the moment of switching off. The polarity, of the voltage source does not change. (Fig 2), The polarity of direct voltage (commonly known as DC, voltage) is positive (+ve) and negative (–ve). The direction, of conventional flow of current is taken as from the positive, to the negative terminal outside the source. (Fig 3), , Type of current (Fig 4), , Voltage is the cause of electrical current. If a direct current, flows through a circuit, the movement of electrons in the, circuit is unidirectional., Thus direct current remains at the same value from the, moment of switching on to the moment of switching off., (Direct current in common usage is known as DC current.), , Construction: Draughtsman Civil - (NSQF Level - 5): Related Theory for Exercise 2.7.82, , Copyright Free under CC BY Licence, , 217

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AC Supply, The source of AC supply is AC generators (alternators)., (Fig 5a) The supply from a transformer (Fig 5b) is also, AC., , AC supply is expressed by the effective value of the, voltage, and the number of times it changes in one second, is known as frequency. Frequency is represented by 'F', and its unit is in Hertz(Hz)., For example, the AC supply used for lighting is 240V 50, Hz. (Alternating voltage in common use is known as AC, voltage.) AC supply terminals are marked as phase/line(L), and neutral(N)., Current is caused in an electric circuit due to the application of voltage. If an alternating voltage is applied to an, electrical circuit, an alternating current (commonly known, as AC current) will flow. (Figs 7 and 8), , Alternating voltage, AC supply sources change their polarity constantly, and, consequently the direction of voltage. The voltage, supplied to our homes by power plants is alternating., Fig 6 shows a sinusoidal alternating voltage over time, (wave-form)., , Polarity test in DC, Objectives: At the end of this lesson you shall be able to, • state the importance of polarity, • explain the method of identifying the polarity of DC sources by MC voltmeter, • explain how to use a neon lamp/indicator for testing polarity., • state the effects of electric current., Polarity, , Importance of the polarity, , The polarity of a DC supply source should be identified, as positive or negative. We can also use the term to indicate how an electric device is to be connected to the, supply. For example, when putting new cells in a transistor radio we must put the cells correctly such that the, positive terminal of one cell connects to the positive terminal of the radio and the negative terminal of the other, cell connects to the negative terminal of the radio as, shown in Fig 1., , Direct current supply has fixed polarity, positive and, negative marked as + and –. Electric devices which have, positive and negative identifications on their terminals are, said to be polarised. When connecting such devices to a, source of voltage (such as a battery or DC supply) we, must observe the correct polarity markings. That is the, positive terminal of the device must be connected to the, positive terminal of the source, and the negative to the, , 218, , Construction: Draughtsman Civil - (NSQF Level - 5): Related Theory for Exercise 2.7.82, , Copyright Free under CC BY Licence

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negative. If the polarity is not observed correctly (that is,, if +ve is connected to –ve) the device will not function, and may be damaged., , deflects as in Fig 5, below zero, the polarity is not correct. From this we conclude that the meter reads in forward direction only if the instrument is connected with, correct polarity as per the markings on the instrument, terminals., , To get more voltage, current and power, the voltage, sources like cells, batteries and generator are often, connected in series, or in parallel or in series/parallel, combination circuit. To connect them in such a manner, we must know the correct polarity of the source. Fig 2, shows the method of connecting 3 cells in series to get, more voltage. Fig 3 shows connection of 3 cells in parallel, for getting more current., , Polarity of the battery, , Testing polarity by MC meter, The polarity of a cell is determined by the use of a moving coil volt-meter. The terminals of the MC meter are, marked as +ve and –ve. MC meters are called as, polarised as they have to be connected as per the polarity marking. By using a low range (0-3V) MC voltmeter, we can find out the voltage of a cell. The connections are, made as per Fig 4 the voltmeter reads 1.5 volts. The, polarity of the cell is correct as per the marked polarity, on the meter terminals. If the pointer of the voltmeter, , To determine the polarity of the terminals of an unmarked, battery, that is +ve and –ve we can use a low range MC, voltmeter. If the voltmeter reads positive reading, say 10, or 12 volts then the polarity of the terminals are correct, as per the markings on the meter terminals. If the meter, reading is negative, that is below zero, the battery polarity is not correct with respect to the meter., Polarity of DC supply, In the same way to find out the polarity of DC generator, or a DC source it is advisable to use a moving coil type, voltmeter with a suitable range, of say 0-300 volts. To, protect the meters, always use higher range meters above, the rated voltage of the generator or DC source supply., , Construction: Draughtsman Civil - (NSQF Level - 5): Related Theory for Exercise 2.7.82, , Copyright Free under CC BY Licence, , 219

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Marking made in practice (Fig 6), , Generally in DC source the +ve terminal of the supply, lead is Red in colour and –ve terminal of the supply lead, is Blue or Black in colour. Battery terminals are marked, as +ve and –ve on the body or on the terminal post., •, , For cells on top of the cell is marked as +ve and the, bottom is marked as –ve, , •, , The battery terminal is marked as + and is Red in, colour, and the other terminal is marked as – and, Black or Blue in colour. (Fig 7), , Effects of electric current, When an electric current flows through a circuit, is judged, by its effects, which are given below., 1 Chemical effect, , Neon polarity indicator, To check the polarity, a neon lamp in series with a, 220 k ohms resistance could be used (as shown in, Fig 8). Touch the probes of the neon lamp circuit across, the circuit to be tested. The lamp will light when voltage, is present. If both electrodes in the lamp glow, you have, an AC power source. If only one electrode glows, the, voltage is DC and the lighted electrode will be on the side, of the negative polarity of the source. Therefore, you also, have a polarity check on DC circuits. (Fig 8) A commercial neon polarity indicator is shown in Fig 9. It has an, indicating glass window in which the polarity touched by, the pointed end of the indicator will be displayed as +ve, or –ve through neon signs., , When an electric current is passed through a conducting, liquid (i.e. acidulated water) called an electrolyte, it is, decomposed into its constituents due to chemical action., The practical application of this effect is utilized in, electroplating, block making, battery charging, metal, refinery, etc., 2 Heating effect, When an electric potential is applied to a conductor, the, flow of electrons is opposed by the resistance of the, conductor and thus some heat is produced. The heat, produced may be greater or lesser according to the, circumstances, but some heat is always produced. The, application of this effect is in the use of electric presses,, heaters, electric lamps, etc., 3 Magnetic effect, When a magnetic compass is placed under a current, carrying wire, it is deflected. It shows that there is some, relation between the current and magnetism. The wire, carrying current does not become magnet but produces, , 220, , Construction: Draughtsman Civil - (NSQF Level - 5): Related Theory for Exercise 2.7.82, , Copyright Free under CC BY Licence

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a magnetic field in the space. If this wire is wound on an, iron core (i.e. bar), it becomes an electro-magnet. This, effect of electric current is applied in electric balls, motors,, fans, electric instruments, etc., , 5 Special rays effect, , 4 Gas ionization effect, , 6 Shock effect, , When electrons pass through a certain gase sealed in a, glass tube, it becomes ionised and starts emitting light, rays, such as in fluorescent tubes, mercury vapour lamps,, sodium vapour lamps, neon lamps, etc., , The flow of current through the human body may cause, a severe shock or even death in many cases. If this, current is controlled to a specific value, this effect of, current can be used to give light shocks to the brain for, the treatment of mental patients., , Special rays like X-rays and laser rays can also be, developed by means of an electric current., , Construction: Draughtsman Civil - (NSQF Level - 5): Related Theory for Exercise 2.7.82, , Copyright Free under CC BY Licence, , 221

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Construction, Draughtsman Civil - Floor, , Related Theory for Exercise 2.8.83, , Floor (Ground), Objectives: At the end of this lesson you shall be able to, • define the floor, • purpose, • flooring materials & factors affecting the choice of flooring material, • components of a floor, • types of floors., Introduction, , 11 Wood or timber, , In order to sub-divide the portion between the plinth level, or basement level and roof level, solid constructions are, carried out. These constructions are known as floors and, exposed top surface of floors are termed as floorings., Ground floors or basement floors are termed as flooring., Ground floor or basement floors, which directly kept on, the ground, do not require the provision of a floor. But, they are provided with suitable type of flooring. In addition, to that measures should be taken to prevent the entry at, dampers and for giving thermal insulation., Definition, It is a horizontal element of a building structure, which, divide the building into different levels, for the purpose, of creating more accommodation within a restricted, space, one above the other and provide support for the, occupants, furniture and equipment of a building., , 12 Asphalt, 13 Rubber, 14 Linoleum, 15 Cork, Factors affecting the selection of flooring materials, 1 Appearance: The material should give pleasing, appearance and if should produce the colour effect, with the use of building., 2 Cleanliness: It should be such that it can be cleaned, easily and effectively and has resistance against oil,, grease etc., 3 Comfort: It should possess good thermal insulation, to give comfort for the residents., 4 Cost: Cost should be reasonable., , Purpose, , 5 Damp resistance: The material should offer sufficient, resistance against dampness., , The purpose of floor is to creating more accommodation, within a restricteed space, one above the other and, provide support for the occupants, furniture and, equipment of a building., , 6 Durability: Resistance to wear, tear and chemical, action., 7 Fire resistant:, 8 Easy to give maintenance, , Flooring Materials, , 9 Noiseless while Len which using the floor., , For giving pleasing appearance to the upper surface of, the floor, various materials are used. The common, materials used as flooring are:, 1 Mud, , 10 Non stippery surface but smooth enough to clean, easily., Components of Floor, Floor is composed of two essential components., , 2 Muram, 3 Bricks, , 1 Sub floor – base course or floor base., , 4 Flag Stones, , 2 Floor covering, or simply flooring., , 5 Concrete, , Sub Floor: It provides proper support to floor covering, and the super imposed load are carried by it., , 6 Terrazzo, 7 Mosaic, 8 Tiles, , Floor covering: It provides a smooth, clean, impervious, and durable surface., , 9 Marble, 10 Granolithic Finish, 222, , Copyright Free under CC BY Licence

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Types of floor, , 5 After ramming, the surface is saturated with a 6 mm, thin film of water, , The floor is mainly divided in to two:, 1 Ground Floor, , 6 The surface well - trampled under the feet of workmen, till the cream of muram rises to the top., 7 The surface is levelled and then kept in that state for, a day, and then rammed again with wooden rammers., , 2 Upper floor, Ground floor (basement floor) (Fig 1), , 8 The surface is then smeared or rubbed with thin paste, of cow dung and rammed again for two days, during, morning hours., 9 Finally, a coating of mud - cow dung mix is applied, over the surface., Brick floors (Fig 2), , The floors resting directly on the ground surface are, known as ground floors. They do not require provision, of a floor. The major problems of a ground floor are damp, exclusion and thermal insulation. For this purpose it is, usually provided a bedding concrete of 1:4:8., Material used for ground floor, Mud floors, 1 Such flooring is cheap, hard and fairly impervious., 2 Easy to construct and easy to maintain., , 1 These floors are used in cheap type of construction, such as stores, godowns, Warehouses etc., , 3 It has good thermal insulation property., , 2 The brick to be used should be of uniform shape and, colour and good quality., , 4 Over a well-prepared ground, a 25 cm thick selected, moist earth (mostly impervious) is spread and is then, rammed well to get a compacted thickness of 15 cm., , 3 It consists of layer of brick (Flat or on edge) laid over, 10 to 15 cm thick P.C.C of 1:8:16, , 5 In order to prevent cracks due to drying, small quantity, of chopped straw is mixed in the moist earth, before, ramming., , Flag Stone Floor (Fig 3), , 6 Sometimes, cow-dung is mixed with earth and a thin, layer of this mix is spread over the compacted layer., 7 Sometimes, a thin paint of cement – cow – dung (1:2, to 1:3) is applied., Muram floors, 1 Muram is a form of disintegrated rock with binding, material., 2 To construct such a floor, a 15 cm thick layer of muram, is laid over prepared sub grade., 3 Over it, a 2.5 cm thick layer of powdered muram (Fine, muram) is spread and water is sprinkled over it., 4 The surface is then rammed well., Construction: Draughtsman Civil - (NSQF Level - 5): Related Theory for Exercise 2.8.83, , Copyright Free under CC BY Licence, , 223

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1 Flagstone is any laminated sand stone available in, 2cm to 4 cm thickness., , 8 It is wetted the previous right of laying topping and, excess water is drained., , 2 The stone slabs are laid on concrete base., , 9 The topping is then laid in square or rectangular, panels, by use of either glass or plain asbestos strips, or by use of wooden battens set on mortar bed., , 3 The sub soil is properly compacted, over which 10 to, 15 cm thick lime concrete or lean cement concrete, is laid., 4 The Flagstones (Stone slabs) are then laid over 20 to, 25 mm thick layer of bed mortar., 5 In laying the slabs, work is started from two diagonally, opposite corners and brought up from both sides., 6 A strings is stretched between two corner slabs first, to correct level., 1 Other slabs are then so laid that their tops touch the, string., 2 If any particular slab falls lower than the string level,, it is re-laid by putting fresh layer of stiff mortar., 3 When the stone slabs are properly set, mortar in the, joints is raked out to a depth of about 15 to 20 mm, and then flush pointed with 1:3 cement mortars., , 10 The topping consists of 1:2:4 cement concrete laid to, the desired thickness (usually 4 cm) in one single, operation. in the panel., 11 Topping concrete is spread evenly with the help of a, straight edge, and its surface is thoroughly tamped, and floated with wooden floats till the cream of, concrete comes at the top., 12 Steel trowel is used for smoothening and finishing, the top surface., 13 The prepared surface is protected from sunlight, rain,, and other damages for 12 to 20 hours., 14 The surface is then properly cured for a period of 7, to 14 days., Terazzo floor (Fig 5), , 4 Proper slope is given to the surface for drainage., 5 The work is properly cured., Cement Concrete floor (Fig 4), , 1 This is commonly used for residential, commercial, and even industrial buildings., 2 It is moderately cheap, quite durable and easy to, construct., 3 The floor consists of two components (1) base, concrete, and (2) topping or wearing surface., 4 The base course may be 7.5 to 10 cm thick, either in, lean cement concrete (1:3:6 to 1:5:10) or line concrete, containing 40% mortar of 1:2 line – sand (or 1 lime:, 1Surkhi: 1 sand) and 60% coarse aggregate of 40mm, nominal size., 5 The base course is laid over well compacted soil, and, leveled to rough surface., 6 It is properly cured., 7 When the base concrete has hardened, its surface is, brushed with stiff broom and cleaned thoroughly., , 224, , 1 In this floor, marble chips of various shades are used, as aggregate., 2 The proportion of terrazzo mix is generally 1:2 to 1:3, i.e, one part of cement to two to threee parts of marble, chips by volume., 3 Prepare base concrete surface of 75cm thick., 4 Over this cement mortar 1:3 of 34 mm thick is laid,, and zigzag line are market on it. Surface is cured for, effect, 5 The cement and marble chips are thoroughly mixed, wet and laid for a thickness 20 mm., 6 The first coat of polishing is done by a coarse, carborandom stone, second coat is done by finely, grained carborandom stone., 7 Wax is applied as a final coat of polishing to get glossy, surface, 8 This floor in generally used for residential buildings,, bath room, Clock rooms, etc., , Construction: Draughtsman Civil - (NSQF Level - 5): Related Theory for Exercise 2.8.83, , Copyright Free under CC BY Licence

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Mosaic floor (Fig 6), , (surkhi):1 (coarse sand) mix is spread under the area, of each individual slab., 5 The marble slab is then lifted up, and fresh mortar is, added to the hollows of the bedding mortar., 6 The mortar is allowed to harden slightly, cement slurry, is spread over it, the edges of already laid slabs are, smeared with cement slurry paste, and then the, marble slab is placed in position., 7 It is gently pushed with wooden mallet so that cement, pastes oozes out. This is cleaned with cloth., , 1 Mosaic flooring is made of small pieces of broken, tiles of china glazed or of cement, or of marble,, arranged in different pattern., 2 These pieces are cut to desired shapes and sizes., 3 A concrete base is prepared as in the case of concrete, flooring, and over it 5 to 8 cm lime – surkhi mortar is, spread and levelled., 4 On this, a 3 mm thick cementing material, in the form, of pate comparising two parts of slaked lime, one part, of powered marble and one part of puzzolana, material, is spread and is left dry for about 4 hours., 5 Small pieces of broken tiles or marble pieces of, different colours are arranged in definite patterns and, hammered into the cementing layer., , 8 The paved area is properly cured for about a week., Granolithic floors, 1 It is a finished coat, which is provided over a concrete, surface., 2 The concrete mix used is 1:1:2 or 1:1:3. And, aggregate used may be basalt, lime stone or quartz, silt., 3 The granolithic layer of concrete is laid before the, base concrete is set to get a monolithic construction., 4 The minimum thickness of finishing should be 12 mm., Wooden floors (Fig 7), , 6 The surface is gently rolled by a stone roller., 7 Sprinkle water over the surface., 8 Surface is allowed to dry for 1 day, and is thereafter,, rubbed with a pumice stone., 9 The surface is polished smooth., 10 The floor is allowed to dry for two weeks before use., Tiled floors, 1 Firstly, levelled hard bed or 15 cm thick P.C.C is, preparedd., 2 Over this bed, a thin layer of cement mortr 1:1 is laid., 3 Then pre cast tiles of cement concrete or pottery are, laid over it carefully, filling the joints with mortar, which, are generally paper thick., 4 Extra cement is wiped off and joints cleaned with saw, dust. Afterr curing the surface is rubbed and polished., Marble, , 1 In hilly areas where the wood is available in a large, quantity and on the other hand, the climate is damp,, wooden floors are used., 2 These are also used in dancing halls, auditoriums,, etc., 3 The timber to be used for flooring should be of the, best quality, well – seasoned and free from cracks,, knots, flaws and other defects., , 1 It is a superior type of flooring, used in residential, buildings, hospitals, sanatoriums, temples etc. Where, extra cleanliness is an essential requirement., , Asphalt floor, , 2 Marble slab may be laid in different sizes, usually in, rectangular or square shapes., 3 The base concrete is prepared in the same manner, as that for concrete flooring., , 2 The asphalt tiles, which are produced from natural, asphalt, bitumen, asbestos fiber and mineral pigments, are available in different sizes and in a variety of, colours., , 4 Over the base concrete, 20 mm thick bedding mortar, of either 1:4 cement sand mix or (lime putty): 1, , 3 The asphalt terrazzo is formed by the combination of, black or coloured asphalt with marble chips., , 1 The asphalt flooring can be carried out in a variety of, colours and in different forms., , Construction: Draughtsman Civil - (NSQF Level - 5): Related Theory for Exercise 2.8.83, , Copyright Free under CC BY Licence, , 225

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4 This terrazzo is laid hot and the surface is made, smooth by a trowel., 5 The asphalt flooring is water-proof (no space), vermin, proof, dustless and joint less., 6 It is used for surface subjected to heavy wear as, incase of dairies, breweries, hospitals, shops,, restaurants, loading platforms, swimming pools,, terrace etc., , 4 Cork Carpet is manufactured by heating granules of, cork with linseed oil and compressing it by rolling on, canvas., 5 Cork tiles are manufactured from high grade cork or, shearing compressed in module to a thickness of, 12mm and baked subsequently., Glass floor (Fig 8), , Rubber floor, 1 It consists of sheets or tiles of rubber, in a variety of, patterns and colours., 2 The sheet or tile is manufactured by mixing pure, rubber with fillers such as cotton fibre, granulated cork, or asbestos fibre., 3 The sheets or tiles are fixed to concrete base or wood, by means of appropriate adhesive., 4 Rubber flooring is resilient and noise proof., 5 However, they are costly., 6 They are used only in office or public building., Linoleum floor, 1 It is a covering which is available in rolls, and which, is spread directly on concrete or wooden flooring., 2 Linoleum sheet is manufactured by mixing oxidized, linseed oil in gum, resins, pigments, wood flour, cork, dust and other filler materials., 3 The sheets are either plain or printed, and are, available in 2 to 6 mm thickness, and 2 to 4 m width., 4 Linoleum tiles are also available, which can be fixed, (or glued) to concrete base or wood floor, in different, patterns., , 1 This is special purpose flooring, used in, circumstances where it is desired to transmit light from, upper floor to lower floor, and specially to admit light, at the basement from the upper floor., 2 Structural glass is available in the form of tiles or slabs,, in thickness varying from 12 to 30 mm., 3 These are fixed in closely spaced frames so that glass, and the frame can sustain anticipated loads., 4 Glass flooring is very costly, and is not commonly, used., Plastic or PVC floor, , 5 Linoleum sheet is either spread as such, or also may, be glued to the base by inserting a layer of saturated, felt., , 1 It is made of plastic material, called Poly Vinyl Chloride, (P.V.C), fabricated in the form of tiles of different sizes, and different colour shades., , 6 Linoleum coverings are attractive, resilient, durable, and cheap, and can be cleared very easily., , 2 These tiles are now widely used in all residential as, well as non –residential buildings., , 7 However, it is subjected to rotting when kept wet or, moist for some time., , 3 The tiles are laid on concrete base., , 8 It cannot, therefore, be used for bath room, kitchens, etc., Cork floor, 1 This type of flooring is perfectly noiseless, and is used, in libraries, theatres, art galleries, broadcasting station, etc., 2 Cork which is the outer bark of cork oak tree, is, available in the form of cork carpet and cork tiles., 3 It is fixed to concrete base by inserting a layer of, saturated felt., 226, , 4 Adhesive of specified make is applied on the base, as well as on the back of P.V.C tile with the help of a, notched trowel., 5 The tile is laid when the adhesive has set sufficiently, (say within 30 minutes of its application); it is gently, pressed with the help of a 5 kg weight wooden roller, and the oozing out adhesive is wiped off., 6 The floor is washed with warm soap water before use., P.V.C tile flooring is resilient, smooth, good looking, and can be easily cleaned., 7 However, it is costly and slippery, and can be, damaged very easily when in contract with burning, objects., , Construction: Draughtsman Civil - (NSQF Level - 5): Related Theory for Exercise 2.8.83, , Copyright Free under CC BY Licence

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Construction, Draughtsman Civil - Floor, , Related Theory for Exercise 2.8.84, , Upper floors, Objectives: At the end of this lesson you shall be able to, • define the upper floor, • purpose, • types of upper floors, • choice of floor., Introduction, , Definition, , An upper floor is basically a principal structural element,, and the general structural design of a building will greatly, influence the choice of the type of floor. Upper floors, are supported either on the walls or on columns; they, have, therefore, the major problems of strength and, stability., , The floors constructed above the ground floor are known, as upper floors., , The structural design of upper floors has to be such as, to support the loads set up by the use of the building, in, addition to the self weight and the weight of partitions, etc. However, the flooring materials are practically the, same as used for ground floor., , Purpose, To create more accommodation with in a restricted space,, one above the other and to provide support for the, occupants, furniture and equipment of a building., Types of floor, Floors are classified based on types of materials and, construction as below., , Floors, , Timber floors, , Composite floors, , Single joint floor, , Double flange stone floor, , Double joint timber floor, , Filler joist floor, , Framed or triple joist floor, , jack arch floor, R.C.C floor, Hollow block or rib floor, Pre- cast concrete floor, , Timber Floor, This type of floor is preferred in hilly areas where timber, is easily available, normally it is used in auditoriums, where dances or dramas are performed…, , •, , When the span of joist exceeds about 2.4m, herring, bone strutting are provided., , •, , Ends of this struts are nailed to the joists., , •, , At the end, the wedges are provided between the wall, and the joist., , A Single joist timber floor (Fig 1), B Double joist timber floor (Fig 2), •, , It is adopted for maximum span of 3.6 m, , •, , These floors consist of single joists which are place, below the floor boards., , •, , The joists are usually at a centre to centre distance, of 300 mm to 450 mm., , •, , The joists are supported on wall – plates at their ends., , 1 It is stronger than single joist timber floor. Span is up, to 7.5m, 2 In this type of floor, the intermediate supports, known, as the binders, are provided for the bridging joists., 3 The end of binders rest on wooden stone blocks., , 227, , Copyright Free under CC BY Licence

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1 It is suitable for span greater than 7.5 m, 2 In this type of floors, the intermediate support, known, as the girders, are provided to support the binders., 3 The girders are placed at a centre to centre distance, of 3 m., 4 The ends of binders are supported on iron stirrups, which are fixed to the girders., 5 The ends of girders rest in walls on stone or concrete, templates., Composite floor, If floors are composed of more than one material, then, they are known as composite floors. It is more fire, resistant and sound proof than timber floor. It can be, easily cleaned and possesses better hygienic property., It can be adopted for long spans., A – Double flagstone floor (Fig 4), , 1 Flagstones of two layers are used., 2 If span is about 4 m only steel joists are provided., 3 Top layer of flag stone is finished., B – Filler joist floor (Fig 5), C Framed or triple joist timber floor (Fig 3), , 1 Small sections of R S J are placed in concrete., 2 The joists may either rest on wall or on steel beams., 3 The joists act as reinforcement., 4 The concrete should completely surround the joist., C – Jack arch floor (Fig 6), 1 Brick or concrete arches are constructed and they, rest on the lower flange of mild steel joist., 2 The joists are placed at a distance of about 800 mm, to 1200 mm centre to centre., 228, , Construction: Draughtsman Civil - (NSQF Level - 5): Related Theory for Exercise 2.8.84, , Copyright Free under CC BY Licence

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3 Rise of arch should be 100 mm to 200 mm., , Hallow block or rib floor, , 4 The minimum depth of concrete at the crown should, be 150mm., , 1 Hollow blocks of clay or concrete are used to reduce, self weight of floor., 2 This type of floor is economical, fire-proof, soundproof and light in weight., 3 Plumbing and electrical installations can be, conveniently carried through the hollow blocks without, affecting the appearance., 4 These floors are widely used for building like hospitals,, hotels, schools, offices, etc., E-Pre-cast concrete floor, , D – R.C.C floor, 1 Steel bars and concrete are used to form a floor., Beams and slabs are designed as per load on floor., 2 For R.C.C slab, the thickness varies from 80 mm to, 150 mm and the main reinforcement is generally in, the form of mild steel bars of diameter varying from, 9mm to 12 mm., 3 R.C.C beams are to be provided when the span of, slab exceeds 4 m or so., 4 The location, spacing and bending of steel bars are, to be decided carefully., 5 RCC work may be cast –in-situ or pre-cast, the former, being very common., , 1 With the development of pre-cast concrete, construction technique, it is possible to prepare the, pre-cast unit for the floor., 2 These pre-cast units are available in suitable size and, can be conveniently handled, transported and fixed., 3 They may be supported either on walls or on rolled, steel joists., 4 The sides of each unit contain grooves which are used, to connect the adjacent units., 5 The members are light in weight and hence the cost, proves to be economical., 6 They are fire-proof and sound-proof., 7 They do not require formwork during construction., 8 They have good thermal insulation., , 6 Suitable flooring can be provided on the surface of, an R C.C floor., , Choice of floor, , 7 The R.C.C floors are less costly, durable, and easy, to construct and fire proof., , Choice of floor depends upon,, , 8 However, they are likely to transmit sound., , 1 Span, , 9 In any case, the R.C.C. floors are fast replacing other, types of floors., , 2 Maximum load on the floor, , 10 The reinforcement in the flat slab can be arranged, either in two-way system or four-way system., , 4 Material and labour available, , 3 Type of construction, , 5 Purpose or use of building., , 11 For ordinary loading conditions, the two-way system, of reinforcement is generally preferred., , Construction: Draughtsman Civil - (NSQF Level - 5): Related Theory for Exercise 2.8.84, , Copyright Free under CC BY Licence, , 229

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Construction, Draughtsman Civil - Vertical movement, , Related Theory for Exercise 2.9.85, , Vertical transportation, Objectives: At the end of this lesson you shall be able to, • enlist the different means of vertical traansportaion, • define ramp, • explain the features of ramp, • state the materials used and purpose of ramp, • express the pitcher of ladder, stair & ramp., Introduction, Vertical transportation is a phrase used to describe the, various means of travelling between floors in a building., All buildings with more than one storey have at least one, means of vertical transportation. The provision and position of vertical transportation is a very important consideration while designing buildings in order to ensure all, the occupants of the building can escape safely in the, event of a fire., , Types of vertical transportation used in different, buildings, -, , Ramps, , -, , Ladder, , -, , Stair, , -, , Lifts (Elevators), , -, , Escalators, , Among these stairs are most commonly used for vertical, transportation in residential buildings, lifts in workshops, are lifts & escalators in commercial buildings., Ramps, Definition, A ramp is a sloping surface and it is adopted as a substitute for stair for easy connection between the floors. They, are especially useful when large numbers of people or, vehicles are to be moved from floor to floor., , The important features of the ramps are as follows, •, , Minimum slope is 1 in 10, maximum slope is 1 in 15, , •, , Shape need not be straight, , 230, , Copyright Free under CC BY Licence

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•, , Provided with hand rail on both sides, , •, , Minimum width of ramp for hospital should be 2.25m, , •, , Ramp leads directly from open space on ground level, to upper floor levels., , •, , Used in garages, railway stations, stadium, town hall,, hospital etc., , Materials, The materials used for ramp construction are rock or, stone, brick, timber, steel, plain concrete, reinforced concrete etc., Purpose, Communication between different levels of building., Easy and comfort transportation for vehicles, disable persons etc., Improves aesthetic views for large buildings., Ladder (Fig 1), A structure of wood, metal, or rope, commonly consisting of two sidepieces between which a series of bars or, rungs are set as suitable distances, forming a means of, climbing up or down., , Construction: Draughtsman Civil - (NSQF Level - 5): Related Theory for Exercise 2.9.85, , Copyright Free under CC BY Licence, , 231

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Stairs, Objectives : At the end of this lesson, you shall be able to,, • define stair, stair case, • enlist the technical terms, • define the different types of slip., Introduction, A stair is a convenient means of access between the floors, of a building. It is constructed to provide ready, easy,, comfortable and safe ascent/descent with series of steps, that are neither laborious nor difficult to climb within an, enclosure called stairwell (Staircase)., Definition, A stair is defined as a series of steps suitably arranged, for the purpose of connecting different floors of a building. It is provided to afford the means of ascending and, descending between floors and landing. The room or, enclosure of a building in which the stair is located is, known as stair case. The opening or space occupied by, the stair is known as stair way. It should be suitably located to provide easy access to all the rooms., The definitions of technical terms used in connection with, the stair are:-, , Sl.No, , Terms, , Definition, , 1., , Tread, , The horizontal upper portion of step, , 2., , Going, , Horizontal distance between faces of two consecutive risers., , 3., , Riser, , The vertical front member of step, , 4., , Rise, , Vertical distance between two successive treads, , 5., , Flight, , Series of step between landings, , 6., , Nosing, , The projecting part of the tread beyond the face of riser, , 7., , Scotia, , Additional moulding provided under the nosing to improve the elevation of step and to, provide extra strength to nosing end, , 8., , Walking Line, , The approximate line of movement of people on a stair. It may be 45 cm from the, centre of handrail., , 9., , Head room, , The vertical distance between the nosing of one flight and the bottom of the flight, immediately above., , 232, , Construction: Draughtsman Civil - (NSQF Level - 5): Related Theory for Exercise 2.9.85, , Copyright Free under CC BY Licence

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10., , Run, , Total length of stair in a horizontal plane. It includes the lengths of landings also., , 11, , Soffit, , The under surface of stair, , 12, , Waist, , The thickness if structural slab in case of RCC stair, , 13, , Stringers, , Inclined member in wooden stairs acting as wooden beams to support the steps., , 14, , String, , The inclined member of a stair which supports the ends of step is known as string., , a Cut or, open string., , In the cut or open string, the upper edge is cut away to receives the ends of steps as, shown in fig 3., , b A closed, or housed, string., , In the closed or housed string, the ends of steps are housed between straight parallel, edges of the string as shown in fig 3., , Construction: Draughtsman Civil - (NSQF Level - 5): Related Theory for Exercise 2.9.85, , Copyright Free under CC BY Licence, , 233

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15, , Pitch, , The angle of inclination of stair with the floor., , 16, , Landing, , Horizontal platform between two flights to change of direction and to take rest for users., , 17, , Baluster, , The vertical member fixed between string and hand rail to give support to hand rail, , 18, , Handrail, , The inclined rail over the string, , 19, , Newel post, , Vertical member placed at the end of flights to connect the ends of string and handrail., , 20, , Balustrade, or Barrister, , The combined frame work of hand rail and baluster., , STEPS: It is a portion of stairs which permits ascent or decent it comprises of a tread and riser. A stair is composed, of a set of steps., Types of steps (Fig 4), Sl. no, , Terms, , Definition, , 1, , Flier, , Ordinary step of rectangular shape in plan, , 2, , Bull nose step, , It forms a circular quadrant in plan and provided at the bottom of flight, , 3, , Commode step, , This step has a curved rise and tread, , 4, , Dancing step, , Step do not radiate from common centre, , 5, , Round ended step, , Similar to bull nose step except that its ends are semicircular in plan, , 6, , Splayed step, , One end or both ends splayed in plan., , 7, , Winder, , Tapering step and used to change the direction of flight, , 234, , Construction: Draughtsman Civil - (NSQF Level - 5): Related Theory for Exercise 2.9.85, , Copyright Free under CC BY Licence

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Construction: Draughtsman Civil - (NSQF Level - 5): Related Theory for Exercise 2.9.85, , Copyright Free under CC BY Licence, , 235

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Construction, Draughtsman Civil - Vertical movement, , Related Theory for Exercise 2.9.86, , Classification of stairs according to shape, Objectives : At the end of this lesson, you shall be able to, • classify the means of vertical transportation, • explain types of stairs according to shape., Means of transportation between the floor, , Ramp, , Ladder, , Stair, , Escalator, , According to materials used, , Brick, stair, , Wooden, stair, , Stone, stair, , Quater, stair, Bifurcated, stair, , Lift, , According to shape, , Metal, stair, , R.C.C, stair, , Half turn, stair, , Dog- legged, stair, , Straight, stair, , Turning, stair, , Circular, or Spiral, stair, , Geometrical, stair, , Three quarter, stair, , Open newel, stair, , Stair, Types of stairs, Stairs are classified as follows., A Straight stair, B Turning stair, C Circular or spiral stair, D Geometrical stair, , B Turning stair : In case of turning stair the flights takes, turn., , A Straight stair : In case of straight stair all steps leads, in one direction only. This type of stair may consist of one, or more flights and they are used when space available, for staircase is long but narrow in shape. (Fig 1), , The usual type of turning stair are described below., 1 Quarter-turn stair, , 236, , Copyright Free under CC BY Licence

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i, , Biffurcated stair, , ii Half-turn stair, iii 3-Quarter-turn stair, i, , Quarter-turn stair (Fig 2), , b Open newel stair (Fig 5), , A stair turning through one right angle is known as a quarter-turn stair., Biffurcated stair (Fig 3), , If a quarter turn stair is branched into two flights. At a, landing as shown in figure is known as buffercated stair., , In case of an open newel stair there is a well or opening, between the flights in plan. This well may be rectangular, or any geometrical shape and it can be used for fixing lift., These stair are useful where the total width of the space, available for staircase has width greater than twice the, width of the step., iii Three quarter turn stair (Fig 6), , ii Half-turn stair, A stair turning through two right angle is known is a halfturn stair. A half-turn stair may be dog legged stair, and, open newel stair., a Dog-legged stair, b Open-newel stair, a Dog-legged stair (Fig 4), The stair its flights run in opposite directions and there is, no space between them in space plan. The stair are useful where total width of space available for stair case is, equal to twice the width of step., , A stair turning through three right angles is known as three, quarter-turn stair as shown in figure. In this case an open, well is formed., , Construction: Draughtsman Civil - (NSQF Level - 5): Related Theory for Exercise 2.9.86, , Copyright Free under CC BY Licence, , 237

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C Circular helical or spiral stair (Fig 7), , In this type of stair, the steps are radiate from the centre., The flights consist of winders only and they may be continued through any desired number of turns. Spiral stair, may be constructed of cast-Iron, Mild steel, concrete., Usually the structural design and construction of spiral, stair are complicated in nature. For concrete spiral stair,, steel reinforcement is heavy and framework is complicated so it is expensive. Spiral stair is useful where space, available is limited and where traffic is less., , D Geometric Stair (Fig 8), , These stairs have any geometrical shape and they do, not require newel post. The handrail of a geometrical stair, continuous without interruption and without any angular, turns. Considerable skill is required for the construction, of a geometrical stair and it is found that a geometrical, stair is weaker than corresponding open-newel stair., , Classifications stair according to material and requirements of good stair, Objectives : At the end of this lesson, you shall be able to,, • classify the stair according to materials, • explain the requirements of a good stairs, • design the stair case as per the given data., Introduction, , Stone Stair, , Any well planned stair should meet the following criteria, for easy, quick and safe ascent/decent., , The stone to be used for the construction of stair should, be hard, non-absorbent and they should possess enough, resistance to the action of fire. These stairs are used for, ware houses, work shopes etc., , Classification of stair according to materials used, Following are the materials which are commonly used in, the construction of a stair, 1 Stone stair, 2 Wooden stair, , Construction, A stone step may be constructed in any one of the following ways., a Rectangular step (Fig 1), , 3 Brick stair, 4 Metal stair, 5 R.C.C stair, , 238, , In case of a rectangular step the arrangement is made of, as shown in figure. The overlap is about 25 mm to 40, mm. This arrangement results in considerable saving in, labour of cutting and dressing stone., , Construction: Draughtsman Civil - (NSQF Level - 5): Related Theory for Exercise 2.9.86, , Copyright Free under CC BY Licence

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1 The step may be supported and fixed at the both ends, in a wall. The bearing in wall should be at least 10cm, for stairs up to 1.2m width and 20 cm for stairs having, width greater than 1.2m., 2 The step may be supported at one end in a wall and, the other end may be left unsupported, such a cantilever step should not have length more than 1.2m., 3 The step may be supported at one end in a wall and, other end, it may be supported by a steel work., 4 The step may be supported both end on a steel work., b Spandril step (Fig 2), , In this arrangement the steps are cut in such a way so as, to obtain a Plane soffit as shown in figure. This arrangement is used where head room is desired. The soffit, affords a nice appearance and weight of step is also reduced the ends of spandrel step which are built into the, wall should be square so as to provides a horizontal seating or bearing. The soffit can also be made broken or, moulded., , d Tread and Riser step (Fig 4), , In this arrangement the treads and risers of stones are, provided as in case of timber steps. The stone slab treads, and risers are connected by dowels as shown in figure., e Cantilever tread-slab step (Fig 5), , c Build up step (Fig 3), , In this arrangement the steps are formed of treads only., For this purpose only this slab stones are used without, any riser. The steps may either be rectangular or, triangular., 2 Wooden Stair (Timber stair) (Fig 6), These steps used as treads and risers in the form of thin, sawn stone or marble stone, placed over brick or concrete step. The thickness of stone slab may vary from 25 cm., Support and fixing, A stone may be supported and fixed in any one of the, following four ways., , As wooden stairs are light in weight they are mostly used, for residential building. But they have very poor fire resistance. They are un suitable for high raise residential building and for public building. Sometimes hard building wood, such as (Mahogany, out etc) of paper thickness may be, used. The timber used for the construction should be free, from fungal decay and insect attack, and should be usual, traded before use. In timber stair the strings are the support for the stair and act as inclined beam spanning be-, , Construction: Draughtsman Civil - (NSQF Level - 5): Related Theory for Exercise 2.9.86, , Copyright Free under CC BY Licence, , 239

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tween the floor and the landing. For additional support, a, bearer or a carriage may be place under the treads., , The thickness of tread of a timber stair should not be, less than 32mm (1/1/2 inch) and that of riser 25 mm., The nosing of the step should not project beyond the face, of the riser for not more than the thickness of the treads., The thickness of the stinger should be 30-50 mm and, 25-40 cm deep. Landing is constructed of tongued and, grooved boarding on timber joist which are supported on, walls., R.C.C Stair (Fig 9), , 3 Brick Stair (Fig 7), , These stair are now not frequently used. A brick stair, may be made of solid construction or arches may be, provided as shown in figure. This arch reduces the quantity of brickwork and gives additional space which can be, used for making cupboards. In case of brick stair the, treads and risers are generally made equal to the length, of 1 ½ bricks and height of two layer of brick respectively., The treads and risers of brick stair are finished with suitable flooring materials., 4 Metal Stair (Fig 8), The External fire - escape stairs are generally made of, metal. The common metal used for the construction of, stairs is cast-Iron, bronze, mild steel. Metal stairs are, generally is used in factories, workshop, godowns etc. In, metal stairs the stringers are usually of channel sections, and treads and risers are supported on angles, which, are connected to the stringers. Tread and riser of a step, may be of one unit or separate unit. For metal stair metal, baluster with handrail of pipe are used., , 240, , These stairs are new commonly used in all types of construction. They are found to resist wear and fire better, than any other material and can be moulded to the desired shape. The step can be provided with suitable finishing material such as marbles, tiles etc. These stairs, can be easily maintained clean and they are strong, durable and pleasing in appearance. A typical R.C.C stair, is shown in figure 9. The details and placing of reinforcement will naturally depend on design of R.C.C stair. The, steps may be cast-in-sites or pre - cast., Requirements of a good stairs, A well designed stair should fullfill the following requirements., , Construction: Draughtsman Civil - (NSQF Level - 5): Related Theory for Exercise 2.9.86, , Copyright Free under CC BY Licence

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i, , Design of layout : The height of floor is generally, known procedure for determining the no. of treads, and risers is as follows., a The position of 1st and last risers are determined, with regard to the position of doors, windows, verandas etc., , 6 Width, The width of stair should be sufficient for 2 persons to, pass on it simultaneously and for furniture. The minimum, width of stair is taken as about 80 cm., 7 Pitch, , b A convenient height of riser is assumed., c No. of risers equal to total height of floor divided, by height of risers., , The inclination of a stair to the horizontal should be limited to 30°- 45°., 8 Head room, , i.e. no.of risers =, , Total height of floor, Height of riser, , d No. of treads = no. of riser -1, This is due to the fact that the surface of the upper floor, forms the tread for the top step., E.g:- For instance let us assume that height of floor is 3.8, m assume the rise of 14 cm., No. of treads=, , 9 Flight, It is not desirable to provide a flight with more than 12 or, at most 15 steps and not less than 3 steps. Suitable landing should be provided to give comfort and safety to the, users of the stair., 10 Winders, , 3.50, 0.14, , =25 nos, , No. of treads in single flight = 25-1=24 Nos., No. of treads in double flight = 25-2=23 Nos, Depending upon the space available for staircase the type, of stair is selected., Tread and Riser, In - order to make the ascend and descend easy the tread, and risers of a stair should be proportional following rules, of thumb are commonly used for obtaining a satisfactory, proportion of the tread and riser of a step., i, , It should preferable not less than 2m., , Rise in cm X going in cm = 40 to 45, , ii Rise in cm X going in cm = 426 (approximately), iii 2 rise in cm X going in cm = 60 (approximately), Take rise equal to 14 cm and going would be 30 cm as, standard., , These are to be avoided as far as possible. However if, winders are un- avoidable they should be place at the, bottom rather than at the top of the flight., 11 Hand rail, When a flight consists of more than 3 steps a hand rail at, least on one side is considered to be necessity., 12 Location, The stair should be suitably located in the building and, they are well lighted, well ventilated and have convenient, approches., Problem (Fig 10), 1 The inside dimension of a stair case in a residential, building are 2m X 4.6m. The height of floor is 3.3 m, and the roof consist of R.C.C slab of 12 cm thickness. Design a proper layout of R.C.C slab stair for, this building., Section, Adopt a dog - legged stair, , Other combination of rise and going would be 15 X 28, cm, 16 X 26 cm, 17 X 24 cm., , Assume a convenient height of riser say = 18 cm, , 5 Materials and workman ship, , Total hight of floor, Then the no of raiser =, , The stair should be constructed of sound material and, good workman ship so as to impart durability and strength, to the stair., , Height of risen, , Total height = 3.30 + 0.12 = 3.42 m, Height of riser = 18 cm, , Construction: Draughtsman Civil - (NSQF Level - 5): Related Theory for Exercise 2.9.86, , Copyright Free under CC BY Licence, , 241

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Split the number of risers into two flights conveniently, say 12nos in first flight and 7 nos in second flight., No of steps in 1st flight = 12-1 = 11 nos, No. of steps in 2nd flight = 7-1 = 6 nos, Draw the plan and sectional elevation of the dog legged, stair case according the disigned values., , 242, , Construction: Draughtsman Civil - (NSQF Level - 5): Related Theory for Exercise 2.9.86, , Copyright Free under CC BY Licence

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Construction, Draughtsman Civil - Vertical movement, , Related Theory for Exercise 2.9.87, , Lift or elevators, Objectives : At the end of this lesson, you shall be able to, • introduction of Lift or Elevators, • materials, • purpose, • construction, Introduction of lift or elevators, Lift is typically used for two purposes - passengers and, goods. Passenger lifts, as the name suggests, are designed primarily for moving people although they are often used for moving small hand trolleys, persons in wheelchairs and sometimes prams/pushchairs. Passenger lifts, in hospitals are often large enough to accommodate a, hospital bed., , The type, size and number of elevators required is determined by:, •, , The type and tempo of traffic carried, , •, , The total Vertical distance travelled: (The number of, floors served and the floor to floor height), , •, , The average round trip time and elevator speed, desired., , Passenger lifts usually have sliding automatic doors although in smaller building, they may have a hinged door., In both cases, a safety interlock is fitted that prevents the, lift from moving while the doors are open., In most medium sized office buildings, separate good 5, lifts are not required as most goods are small enough to, fit in passenger lifts, however, industrial buildings, shopping malls and large retail stores often have a need for, separate goods lifts., Smallest goods lifts typically utilize automatic sliding doors, in the same manner as passenger lifts. However larger, lifts often utilize sliding concertina doors that must be, opened and closed by the operator but like the passenger lift, there is usually a safety interlock to prevent the lift, from moving unless the doors are closed. Similarly, the, door is locked while the lift is moving for the safety of the, occupants., Definition of lift or elevator, Lift/elevation is a type of vertical transportation equipment, that efficiently moves people or goods between floors of, buildings., They are generally powered by electrical motors that either drive traction cables or counter weight system like a, hoist, or pump hydraulic fluid to raise a cylindrical piston, like a jack., , Factors to consider in planning for elevators in a building, include:, • Size, material and structural equipments for the elevator shaft, • Structural support requirements for the elevator and its, hasting equipment, • Space and enclosure requirements for the elevators, hosting and control equipment, • Electric power and control equipment required, • Lobby space requirements for banks of elevators., , 243, , Copyright Free under CC BY Licence

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Moving stairs (escalator), Objectives : At the end of this lesson, you shall be able to, • definition of moving stairs (Escalators), • features of the escalators, • construction, Definition of moving stairs (escalators), , Location, , These stairs are known as the escalators or ever-moving flights of electrically operated stairs. These escalators are kept in motion by a revolving drum. A few steps, at top and bottom are kept level though moving individually. The only thing a person has to do is to occupy a step, of the escalator for his upward or downward motion., , Before the position of a moving stair in a building is decided, a careful study of flow of traffic should be made or, if it is a new structure, the moving stairs should be located at points where the traffic is likely to be the heaviest., Installation, , Feature of escalators, The important features of the escalators are as follows., Essential parts, An escalator consists essentially of the three parts: steel, trussed framework handrails and an endless belt with, steps. The accurately prepared tracks are attached to, the steel trusses and the steps move on these tracks., Speed and slope, , The various parts of a moving stair are prepared in the, workshop and they are then brought on site for installation. The process of installation should be carefully done, so as to fit each part of the stair in its proper position., This arrangement will ensure smooth working of the stair., Moreover the escalators are arranged in pairs:, i, , upward movement and, , ii downward movement., The units may be placed parallel to each other., , The used accepted speed of the moving stair is 450 mm, per second. A moving stair is in the form of an inclined, bridge between two successive floors and its pitch or inclination to the horizontal is kept 30 degree., , Advantages, The moving stairs consume less power, possess large, capacity and they have continuous operation without the, help of operators. They are used for commercial buildings, railways, airports, etc., , Design, The various components of a moving stair should be carefully designed for the loads likely to come over them. The, important factor affecting the design is the floor to floor, height. The stairway should be kept independent by providing a structural frame around the stair well. This structural frame takes the load of floor handrail, etc., , 244, , 7Construction: Draughtsman Civil - (NSQF Level - 5): Related Theory for Exercise 2.9.87, , Copyright Free under CC BY Licence

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Construction, Related Theory for Exercise 2.10.88, Draughtsman Civil - Roof & roof covering, Roofs, Objectives : At the end of this lesson, you shall be able to, • define Roof, • identify the components of roof, • classify the roof, • forms of pitched roof, • explain the pitched roof., Introduction, , Span: Horizontal distance between internal faces of wall, , Roof is the uppermost part of the building, which is supported on structural members and covered with a roofing, material. Basically roof consists of trusses, portals,, beams, slabs, and domes. The roof covering may be AC, sheet, G I sheet, Wooden shingles, tiles etc., , Rise: The vertical distance between top of ridge piece, and wall plate, Ridge: Wooden member provided in ridge line, , Definition, , Rafters: Members which support extend from eaves to, ridge, , A topmost covered structure provided over a building to, protect from rain, snow, sun, and wind is called Roof., , Common Rafter : Rafter which supports roofs covering, and extend from eaves to ridge, , Elements of roof (Figs 1 & 2), , Principal rafter: Rafter which supports purlins, Jack rafter: Rafters shorter than common rafter, Hip rafter: Rafter provided on the junction of two slopes, Batten: Wooden plank on which roof covering is fixed, Cleat: Small wooden blocks fixed on principal rafter to, prevent purlin from sliding., Pitch: The inclination of roof, Purlin: The member fixed on principal rafter along the, length of roof to carry common rafter or roof covering, Eave Board: Projection of roof beyond the surface of, wall is eave and the wooden board which covers the ends, of common rafters., Valley: When two slopes meet together makes an internal angle, Wall plate: A long wooden member embedded on top of, wall to receive common rafter, Barge board: The wooden planks or boards which are, on the gable end of a roof, Verge: The edge of a roof running between the eaves, and ridge, Gable: The triangular upper part of a wall formed at the, end of a pitched roof., , 245, , Copyright Free under CC BY Licence

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Template : This is a square or rectangular block of stone, or concrete placed under beam or truss, to spread the, load over a large area of the wall., Cleat : These are shorter section of wood or steel (angle, Iron) which are fixed on the principal rafters of trusses to, support the purlin., Classification of Roofs, The roofs are classified into the following three categories., i, , Pitched roof, , ii Flat roof or terraced roof, iii Curved roof, i, , 4 Gambrel roof : This roof is like a gable roof, slopes in, two directions. But there is a break in each slope shown, in figure. (Fig 6), , Pitched roof, , A sloping roof is known as pitched roof., Pitched roofs are basically of following forms:1 Lean to roof : This is the simplest type of steps roof, provided either for a room of small span or for verandah., It has slope only one side a shown in figure. (Fig 3), , 5 Mansard roof or curved roof : Mansard roof like a, hip roof slopes in four directions but each slopes have a, break thus sloping are formed. (Fig 7), , 2 Gable roof : This is the common type of sloping roof, which slope in two directions. The two slopes meet at, the ridge. At the end face a vertical triangle is formed., (Fig 4), 6 Deck roof : A deck roof has slope in all four directions, like a hip roof. But deck or plane surface is formed at the, top. (Fig 8), , 3 Hip roof : This roof is formed by four sloping surface, is four directions. At the end faces sloping triangle are, formed. (Fig 5), 246, , Construction: Draughtsman Civil - (NSQF Level - 5): Related Theory for Exercise 2.10.88, , Copyright Free under CC BY Licence

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Construction: Draughtsman Civil - (NSQF Level - 5): Related Theory for Exercise 2.10.88, , Copyright Free under CC BY Licence, , 247, , King post, , Queen post, , Single roof, , Lean to roof, , Basis forms, , Pitched roof sloping roof, , Hip roof, , Mansard truss, , Truncated truss, , Deck roof, , Bengal teraced, , Mansard roof, , Trussed roof, , Gaimbel roof, , Combination of king and queen, , Double or purlin roof, , Classification, , Gable roof, , Madras terraced, , Flat roof / Terraced roof, , Roofs, , Bell fast truss, , Steel truss, , North light, shell roof, , Shell roof, , Berral vaud, shell roof, , Domes, , Composite truss, , Curved roof

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Definition, A pitched roof is one where the slope in any plane exceeds 10° to the horizontal., Types of pitched roof, , cured in positions at the both ends, the one end being on, the ridge piece and other on the wall plate. Such a roof is, not very much favoured because it has the tendency to, spread out at the feet, it usual plate level and it push out, with a force the wall supporting the wall plate. A couple, roof is suitable for span up to about 3.6 m., , Pitched roof may be broadly classified into following, 1 Single roof, 2 Double roof (Purlin roof), 3 Trussed roof (Frame roof), 1 Single roof, Single roof are those which consist only the rafters which, are supported at the ridge and at the cases. And such, roofs are used only span is limited to 5m otherwise the, size of rafters will be uneconomical the maximum span, of the rafter taken as 2.5 m., , c Couple close Roof (Fig 11), , Single roofs are of four types., a Lean to roof or verandah roof or shed roof, b Couple roof, c Couple close roof, d Collar beam roof, a Lean to roof (Fig 9), , This is the simplest form of sloping roof in which rafters, slope to one side only. The wall to one side of the room, or veranda is taken higher than wall or pillars to other, side. A wooden wall plate is supported either on a steel, corbel or stone corbel or a wooden corbel which are provided at 1 m centre to centre. The usual slope of this, roof is 30°. The rafters are suitably secured on the wall, plate and ever boards, battens and roof covering are provided as shown in figure. A lean to roof is generally used, for sheds, out- houses attached to main building, verandas etc. It is suitable for a maximum span of 2.4 m., b Couple Roof (Fig 10), In this type of roof the common rulers slope upwards from, the opposite walls and they meet on a ridge in the middle, as shown in figure. The common rafters are firmly se248, , This roof is just III rd to a couple roof except that the legs, of the common rafters are concealed by a tie beam as, shown in figure. The tie beam by a tie beam as shown in, figure. The tie beam position tendency of rafters to spread, out and thus the danger of overturning of the walls is, avoided. The tie beam can also be used as a ceiling joist, when required. A close roof can be adopted economically up to span of 4.2. For increased span for load the, rafters may have tendency to say in the middle. This can, be checked by providing a central vertical rod, called king, rod, or king boll which connect the ridge beam and tie, beam is shown in figure., d Collar beam roof (Fig 12), When span increase or when the load is more the rafters, of the couple close roof have the tendency to bend. This, is avoided by rising the tie beam and fixing it 1/3 or 1 ½ of, the vertical height from the wall plate to the ridge. This, rised beam is known as the collar beam or collar tie. This, roof is suitable for span up to 5m. A lower collar position, gives stronger roof. A collar beam provides roof greater, height of the room. If two collar beam crossing each, other are provided to give the appearance of scissors, it, is known as collar and scissors roof., , Construction: Draughtsman Civil - (NSQF Level - 5): Related Theory for Exercise 2.10.88, , Copyright Free under CC BY Licence

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These roof have two basic elements, i, , Rafter, , ii Purlin, The purlins give intermediate support to the rafters and, are supported on end walls. The intermediate supports, so provided in the form of purlins, reduce the size of the, rafters to the economical range. Such a roof is also known, as rafter and purlin roof. The rafters are provided foreclose (42-60 cm c-c). Each rafters is thus supported at 3, points., (II) Double (Purlin) Roof (Fig 13), , i, , At the bottom on wall plate, , ii At the lop by the ridge, iii At the centre by a purlin, For large roof 2 or more purlins may be provided to support each rafter., , Construction: Draughtsman Civil - (NSQF Level - 5): Related Theory for Exercise 2.10.88, , Copyright Free under CC BY Licence, , 249

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Construction, Related Theory for Exercise 2.10.89, Draughtsman Civil - Roof & roof covering, Trussed roof, Objectives : At the end of this lesson, you shall be able to,, • define roof trussed, • sketch the basic types of trussed roofs, • explain the features & uses of basic forms trussed roofs., Definition, Trussed roof is used when the span exceeds 4.8m and, there are no inside supporting walls or partitions for the, purlins then the framed structure which are used to support the root is called truss., Trussed roof, When span of the roof exceeds 5 m and there are no, inside wall to support the purlins, framed structure known, as trusses are provided at suitable interval along the length, of the room. Spanning is generally limited to 3 m for, wooden trusses. The roof may be consist of 3 elements., , In this type of truss the central post known as king post, forms a support for the tie beam. The inclined member, known as struts prevent the principal rafter from bending, in the middle. A king post truss is suitable for roof of span, varying from 5-8 m., Suitable joints are provided between the rafter and tie, beams, between the principal rafter and king post,, between king post and tie beam and at the end of strut., The joints are further strengthened by straps, bots as, shown in figure. King post trusses are placed at centre to, centre distance of 3m., 2 Queen post truss (Fig 2), , a Rafters : Supporting the roofing elements, b Purlins : To provide intermediate support to rafters., c Truss: To provide support to the end of purlin. The, trusses span in the same direction in which the couple of, rafters run. The truss also support the ridge piece or, ridge beam., The different type of trusses are as follows:1 King post truss, 2 Queen post truss, 3 Combination of king post and queen post truss, 4 Mansard truss, 5 Truncated truss, , This truss differs from a king post truss in having two, vertical posts, known as the queen post. The upper end, of a queen post are kept in position by means of horizontal member known as a straining beam. A straining sill is, introduced on the tie beam between the queen post to, counteract the trust of struts. The additional purline are, supported on the queen post as shown in figure., , 8 Composite truss, , A queen post truss in suitable for roof of span varying, from 8-12m. Suitable joints should be provided at all the, connections. The queen post trusses are space at a centre to centre distance of 3m., , 1 King post truss (Fig 1), , 3 Combination of king post and queen post, , 6 Bel - fast truss, 7 Steel truss, , A convenient combination of the king post and queen, post truss can be made to increase the suitability of queen, post truss up to a span of 18m. For this purpose, the, queen post truss is strengthened by one more up right, member known as the princess post on either side as, shown in figure 3., , 250, , Copyright Free under CC BY Licence

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This truss is just similar to the mansard truss except that, the top is finished flat with a gentle slope to one side as, shown in figure. It is used when a room is required in the, roof., 6 Bel fast truss (Fig 7), , 4 Mansard Truss (Fig 4 & 5), , This truss is in the form of a bow. Which consist of thin, sections of timber which its top chord curved. If the roof, covering is light roof truss can be used up to 30 m span., The roof truss is also known as latticed roof truss., 7 Steel roof truss (Figs 8 & 9), , Mansard truss a two- storey truss with upper portion consisting of the king post truss a lower portion of queen, post truss. It is thus a combination of the king post truss, and queen post truss., The mansand truss has two pitches. The upper pitch (King, post truss) varies from 30° - 40° and lower pitch (Queen, post truss) Varies from 60°-70°., 5 Truncated truss (Fig 6), , When the span exceeds 10m, timber truss becomes, heavy and uneconomical. Steel trusser are more economical for large span. The mild steel is easily available, in rolled section of standard shape and size such as channels T- sections and plate. Most of the roof trusser are, Construction: Draughtsman Civil - (NSQF Level - 5): Related Theory for Exercise 2.10.89, , Copyright Free under CC BY Licence, , 251

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fabricated from angle sections because they can resist, effectively both tensions as well as compression and their, jointing is easy. The arrangement and size of various, member of a steel truss depend on the span, loading, and wind pressure., The various type of steel truss along with their suitability, for different span ranges are shown in figure. (Figs 10 to, 18), , 252, , Construction: Draughtsman Civil - (NSQF Level - 5): Related Theory for Exercise 2.10.89, , Copyright Free under CC BY Licence

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8 Composite truss (Fig 18), These trusses are composed of wooden member and, steel or wrought - iron member. The steel is used for, member which have to resist tensile stresses. A composite truss is light in weight and economical., Following are the advantages of steel trusses over timber trusses:-, , 2 They are fire proof and termite proof., 3 They are light in weight and can be fabricated in any, shape., 4 They are strong and more durable as compared to, the timber truss., 5 They can be easily and speedily installed because of, their correction techniques., , 1 The components of steel trusses can be easily obtained in required dimensions and it result into the, minimum wastage of material., , Flat roof, Objectives : At the end of this lesson, you shall be able to,, • define flat Roof, • enumerate advantages and disadvantages., • explain types of flat roof construction, • state the methods of drainage of flat roof and pitched roof, Definition, , Type of flat roof construction, , Flat roof or terraced Roof, A roof which is nearly flat is known as the flat roof. It, should be noted that no roof can be laid perfectly level., The roof must slope in one direction to drain off rain water rapidly and easily to the upper floor, the flat roof can, be constructed on flag stones, RSJ and flag stones, R.C.C, reinforced brickwork, Jack arch roof and pre-cast cement, concrete unit. A flat roof is one where the slope in any, plane does not exceed 10° to the horizontal., , Flat roofs are constructed in similar way as the floors, except that the roof surface is required to be protected, against weather elements such as rain, heat, snow etc., For this purpose, the top surface of roof is given necessary slopes, either two-way or four-way, and also treated, with damp-proofing materials to safeguard against the, effects of rain and snow. In addition, the flat roofs are, either provided with the insulation layer or treated by insulating material to counteract the effects of heat due to, temperature variations., , Advantages of Flat roof, , 1 Mud Terrace Roof,, , 1 The roof can be used as terrace for playing, gardening, sleeping and for celebrating functions., 2 Construction and maintenance is easier., 3 They can be easily made fire proof in comparison to, pitched roof., 4 They are more stable against high wind., 5 They do not require false ceiling which is essential in, pitched roof., 6 The construction of upper floor can be easily done, over flat roof, if so require in future., Disadvantages, , 2 Brick- Concrete Terrace Roofs (Including Madras Terrace Roof), 3 Jack Arch Flat Roofs,, 4 R.C.C or Reinforced Brick Slab Roofs, and, 5 Bengal Terrace Roofs., 1 Mud Terrace Roofs, This type of roof, which is the cheaper and fairly watertight, is extensively used at places of light rainfall. This, mud terrace is constructed out of good white earth, containing a large percentage of sodium salts., 2 Brick - Concrete Terrace Roofs (Fig 1), , 1 A flat roof cannot be used for long span without the, introduction of intermediate pillars and beams., 2 Packets of water are formed on the surface of the, roof it slope is not sufficient., 3 Cracks are developed on the surface of the roof when, variation in temperature in ligh., , In places where the rain fall is heavy and the mud terrace, roofs do not provide a satisfactory water-tight surface,, one of the following methods of roof construction can be, adopted:, In one method, as illustrated in Fig 1 the beams or girders of adequate sizes are placed, spanning across the, , Construction: Draughtsman Civil - (NSQF Level - 5): Related Theory for Exercise 2.10.89, , Copyright Free under CC BY Licence, , 253

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room over the wall on girders or plates of wood or stone, at regular intervals of 1.2 to 2.5 m., , b A layer of fine jelly concrete may be laid over the, first courses of flat tiles. The thickness of layer of, concrete may be 40 mm., 5 As this type of roof is generally used in Bengal state, to cover verandah it is known as Bengal terrace roof., I, , Madras terrace roof (Fig 3), , Above these, the joists are placed at right angles to, beams, etc. At spacing of 30cm centre -to -centre. Over, the joists, either two courses of flat tiles or one course of, bricks are laid and set in lime or cement mortar., This is finally covered with a 7.5 to 10 cm thick plaster of, lime or cement and rubbed to a polished surface., II Bangal terraced roof (Fig 2), , The procedure of construction is as follows, i, , Teakwood joists are placed on rolled steel joist with a, furring piece between the joists and rolled steel Joists., The furring is placed sloping and it gives necessary, slope to the flat roof., , ii A course of specially prepared terrace bricks is laid, diagonally across joist. The size of brick is generally, 15cm X 75cmX 25cm and they are placed on edge in, lime mortar., iii After the brick course has set, a course of brick bat, concrete is laid. The thickness of this course is about, 75 mm and it consist of 3 part of brickbat, 1 part of, gravel and sand and 50% of lime mortar by volume., , The procedure of construction is as follows, 1 The rafters are placed with slight inclination at 13-15, cm. One end of the rafter is inserted into the main, wall to a depth of 20 cm and its other end is supported on a veranda wall or a bressumer. A bressumer, is a beam on lintel or which is provided to support a, wall over an opening., 2 Battens are provided at right angle to the rafter at a, centre distance of about 15 cm., 3 A course of flat tiles are then lard in mortar over the, battens., 4 Finally, the surface of the roof is finished in any one of, the following methods., a Two or more causer of flat tiles may be lard and, then the surface of roof is rubbed or polished with, 2 or 3 coat of plaster., , 254, , iv The concrete is well rammed for 3 days and allowed, to set, v Flat tiles are then laid over the layer of concrete. The, tiles are laid in two courses of 50 mm thickness., vi Finally the surface of the roof is finished with 3 coat of, plaster as shown in figures, with a given slope of 1 is, 30, vii As this type of flat roof construction is widely used in, madras state (Tamil Nadu). It is known as madras, terrace roof., 3 Jack Arch Flat Roofs (Fig 4), These roofs are constructed in a similar way as the Jack, Arch Floors (already described in Under Article 02.01.02), except they are provided with a protective layer at the top, to safeguard against weather elements., , Construction: Draughtsman Civil - (NSQF Level - 5): Related Theory for Exercise 2.10.89, , Copyright Free under CC BY Licence

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Drainage of pitched and flat roofs (Figs 6 & 7), , 4 Reinforced Concrete or Reinforced Brick Flat, Roofs (Fig 5), , These R.C.C or R.B. flat roofs are constructed in a similar way as R.C.C or R.B. floors (already described under, Article 02.01.02) except that they are required to be protected against weather elements, i.e, rain, snow, heat,, etc. A protective covering, consisting of 10 cm thick layer, of lime concrete terracing with some waterproofing compound, is provided over the R.C.C or R.B. slab. This layer, makes the roof leak- proof. The layer of lime concrete is, thoroughly beaten by hand beaters to make it hard, impervious and compact. At the junction of wall, the lime, concrete terracing is taken inside the wall for a depth of, 10-15 cm and the corner is given a round smooth finish., This is done to prevent the accumulation and leakage of, water at junctions. The construction details are illustrated, in Fig 5., , It is necessary to dispose off the rain water that falls on a, pitched roof or a flat roof. In case of a pitched roof, a, trough known as a gutter, is provided at the end of slope, as shown in fig 6. This gutter extends for the full length of, the roof at suitable points along the length of gutter, the, outlet points are provided and in these outlet points, the, ends of rain water pipes are fitted., In case of flat roofs, no gutters are provided and the roof, is provided with such a slope that the rain water is guided, to the outlet points as shown in fig 7. The rain water thus, collected is led through the pipes to the ground level., , The lime terracing is provided with a little slope, usually 1, in 60 to 1 in 100, to drain off the rain water rapidly and, easily., , Construction: Draughtsman Civil - (NSQF Level - 5): Related Theory for Exercise 2.10.89, , Copyright Free under CC BY Licence, , 255

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Curved roof, Objectives : At the end of this lesson, you shall be able to,, • define curved roof, • explain the features & uses of basic forms curved roofs., Definition, These are just the modifications of pitched roofs and are, frequently employed in the modern age to cover large, areas and to give architectural effects. The shell roofs, and domes are the varieties of the curved roofs. They, are useful for big structures such as factories, monumen-, , tal works, libraries, theatres, recreation centres, etc. The, curved roofs may be constructed of timber or R.C.C the, latter material being very common now - a- days. There, are two common forms of a shell roof., , Types of curved roofs, Name, , Description, , Figure, , North light shell roof: These shell roofs are useful for, big structures such as factories, these are used in northern area, , Dome:, , 256, , An element of architecture that, resembles the hollow upper half, of a sphere. Made of various, materials. Used for appearance, , Construction: Draughtsman Civil - (NSQF Level - 5): Related Theory for Exercise 2.10.89, , Copyright Free under CC BY Licence

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Name, Barrel vault :, shell roof, , Description, , Figure, , It is useful when roof is to be pro, vided on circular brick work., , Construction: Draughtsman Civil - (NSQF Level - 5): Related Theory for Exercise 2.10.89, , Copyright Free under CC BY Licence, , 257

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Construction, Related Theory for Exercise 2.10.90, Draughtsman Civil - Roof & roof covering, Roof covering for pitched roofs, Objective : At the end of this lesson, you shall be able to, • state the types of pitched roof covering materials., Roof covering for pitched roofs, , 3 Initial cost and maintenance cost, , Roof covering is an essential component of pitched roof, to be placed over the roof framework to protect it from, main rain, snow, sun, wind and atmospheric agencies., , 4 Durability, 5 Availability of the material, 6 Fabrication facilities, , Following points should be considered before selecting, the type of roof covering for a pitched roof., , 7 Type of roof framework, , 1 Climate of the locality, , 9 Special feature of the locality., , 8 Resistance to fire and heat, , 2 Nature of the building, Roof covering materials, Name, , Description, Fig 11, , Thatch:, , Extensively used in sheds & villages, Cheapest & lightest material Unstable, against wind. Laid on battens., , Tiles:, , These are largely used various kinds of, tiles are used. Commonly used for, covering sloped roof., , Fig 12, , 258, , Copyright Free under CC BY Licence

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Poly, carbonate, sheets, , New type material with high strength,, heat insulation and good light trans, mission. Good weather resistance and, UV protection., , Fig 13, , Fig 14, , Glass, , Structural glass slabs are available at in, different gauges. Fibre glass is both, strong and Height weight. Provide good, light transmission,good appearance,, etc., , Fig 15, , Slates, , It is stratified rocks. Produced in large, number of sizes. Obtained from either, quarries or from mines., , Asbestos, cement, sheets, (AC sheets), , For AC sheets the cement is mixed with, about 15% of asbestos fibres and the, paste so formed are pressed under roll, ers with grooves or teeth with series of, corrugations. They are used for facto, ries, workshops, garages, big halls etc., Available in different trade such as big, six sheet, standard sheet, Trafford sheet, etc., , Fig 16, , Construction: Draughtsman Civil - (NSQF Level - 5): Related Theory for Exercise 2.9.90, , Copyright Free under CC BY Licence, , 259

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Fig 17, , Shingles:, , Wood shingles are the sawn or split thin, pieces of wood obtained from well sea, soned timber resembling slates or tiles., Generally restricted in hilly areas. Laid, in a manner as slates or tiles., , Corrugated, galvanized, iron sheet:, , Prepared by pressing flat wrought iron, plates between rollers with grooves or, teeth and then galvanized with coat of, zinc. Corrugations are present to in, crease strength and rigidity., , Fig 18, , Fig 19, , Ruberoid, , 260, , Light, flexible & waterproof, Not affected, by heat or cold & not attacked by fire., Available in rolls., , Construction: Draughtsman Civil - (NSQF Level - 5): Related Theory for Exercise 2.10.90, , Copyright Free under CC BY Licence

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Copyright Free under CC BY Licence