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GLOBAL ACADEMY OF TECHNOLOGY
i Dept. of Civil Engineering Basic Surveying Practice Manual - 17CVL38
VISION OF THE INSTITUTE
Become a premier institution imparting quality education in engineering and
management to meet the changing needs of society
MISSION OF THE INSTITUTE
M1. Create environment conducive for continuous learning through quality
teaching and learning processes supported by modern infrastructure
M2. Promote Research and Innovation through collaboration with industries
M3. Inculcate ethical values and environmental consciousness through holistic
education programs
GLOBAL ACADEMY OF TECHNOLOGY
ii Dept. of Civil Engineering Basic Surveying Practice Manual - 17CVL38
DEPARTMENT OF CIVIL ENGINEERING
VISION
To become a leading department oriented to serve the basic wants of human
being related to food, air, shelter and transportation, by providing quality
education.
MISSION
M1. Create a favorable environment for learning, teaching & continuous
improvement for implementation of various civil engineering facilities.
M2. Promote professionalism, innovation and research through collaboration
with industries to realize cost & resource effective, stable, quality structures.
M3. Inculcate environmental consciousness and ethical values through
interconnected training programs to ensure sustainability and client satisfaction.
GLOBAL ACADEMY OF TECHNOLOGY
iii Dept. of Civil Engineering Basic Surveying Practice Manual - 17CVL38
PROPROGRAM EDUCATION OBJECTIVES-PEO’s
The program educational objectives of Civil Engineering are, to enable students in,
PEO-1: Developing careers in government and private civil engineering organizations and
other professionally related domains
PEO-2: Pursuing higher studies, and research to develop innovative solutions and technologies
in civil engineering and other multi-disciplinary areas
PEO-3: Improving professional and personal traits aligned to professional ethics and
environmental compulsions
PEO-4: Professional leadership and Successful entrepreneurship
PROGRAM OUTCOMES-PO’s
1. Engineering knowledge: Apply the knowledge of mathematics, science, engineering
fundamentals, and an engineering specialization to the solution of complex engineering
problems.
2. Problem analysis: Identify, formulate, review research literature, and analyze complex
engineering problems reaching substantiated conclusions using first principles of mathematics,
natural sciences, and engineering sciences.
3. Design/development of solutions: Design solutions for complex engineering problems and
design system components or processes that meet the specified needs with appropriate
consideration for the public health and safety, and the cultural, societal, and environmental
considerations.
4. Conduct investigations of complex problems: Use research-based knowledge and research
methods including design of experiments, analysis and interpretation of data, and synthesis of
the information to provide valid conclusions.
5. Modern tool usage: Create, select, and apply appropriate techniques, resources, and modern
engineering and IT tools including prediction and modeling to complex engineering activities
with an understanding of the limitations.
6. The engineer and society: Apply reasoning informed by the contextual knowledge to assess
societal, health, safety, legal and cultural issues and the consequent responsibilities relevant to
the professional engineering practice.
7. Environment and sustainability: Understand the impact of the professional engineering
solutions in societal and environmental contexts, and demonstrate the knowledge of, and need
GLOBAL ACADEMY OF TECHNOLOGY
iv Dept. of Civil Engineering Basic Surveying Practice Manual - 17CVL38
for sustainable development.
8. Ethics: Apply ethical principles and commit to professional ethics and responsibilities and
norms of the engineering practice.
9. Individual and team work: Function effectively as an individual, and as a member or leader
in diverse teams, and in multidisciplinary settings.
10. Communication: Communicate effectively on complex engineering activities with the
engineering community and with society at large, such as, being able to comprehend and write
effective reports and design documentation, make effective presentations, and give and receive
clear instructions.
11. Project management and finance: Demonstrate knowledge and understanding of the
engineering and management principles and apply these to one’s own work, as a member and
leader in a team, to manage projects and in multidisciplinary environments.
12. Life-long learning: Recognize the need for, and have the preparation and ability to engage in
independent and life-long learning in the broadest context of technological change.
PROGRAM SPECIFIC OUTCOMES-PSO’s
PSO-1: Comprehend, analyze and design alternatives for execution of civil engineering
facilities
PSO-2: Apply Standard Codes of Practices and schedule of rates for planning, design, quality
control, estimating & costing of civil engineering projects.
PSO-3: Evaluate the buildings for resource conservation.
GLOBAL ACADEMY OF TECHNOLOGY
v Dept. of Civil Engineering Basic Surveying Practice Manual - 17CVL38
PREFACE
The Basic Surveying Practice Manual contains material that is informational and
instructional, and that sets forth uniform guidelines and accepted practices in civil construction.
The purpose of the manual is to provide uniform guidelines for implementing survey decisions,
and to assure quality and continuity in collection of survey data. The use of the Basic
Surveying PracticeManual is to assure appropriate execution of projects in conformity with the
operational needs of departments dealing with survey data collection and execution of all civil
engineering works. The objective of this manual is not to serve as a general purpose text on the
practice of surveying.
The manual is written in a clear and easy-to-read style, presenting fundamentals of
geodetic engineering at a level that can be quickly grasped by a beginner.
The manual consists of vision and mission of the institute and department. Attendance
requirements and eligibility of a student to attend the geodetic engineering laboratory is
mentioned. Evaluation scheme of student is clearly specified. Step wise procedure for each
experiment as per the university scheme to be conducted is given in the manual along with
related questions. The manual also deals with the demonstration of major instruments used in
preliminary surveying.
GLOBAL ACADEMY OF TECHNOLOGY
vi Dept. of Civil Engineering Basic Surveying Practice Manual - 17CVL38
Regulations Governing
THE DEGREE OF BACHELOR OF ENGINEERING
ATTENDANCE REQUIREMENT
Each semester is considered as a unit and the candidate has to put in a minimum
attendance of 85% in each subject with a provision of condonation of 10% of the
attendance by the Vice-Chancellor on the specific recommendation of the Principal of the
college where the candidate is studying, showing some reasonable cause such as medical
grounds, participation in University level sports, cultural activities, seminars, workshops
and paper presentation, etc.
The basis for the calculation of the attendance shall be the period prescribed by the
University by its calendar of events. For the first semester students, the same is reckoned
from the date of admission to the course as per CET allotment.
The students shall be informed about their attendance position periodically by the
colleges so that the students shall be cautioned to make up the shortage.
A Candidate having shortage of attendance in one or more subjects shall have to repeat
the whole semester and such candidates shall not be permitted to take admission to next
higher semester. Such students shall take readmission to the same semester in the
subsequent academic year.
INTERNAL ASSESSMENT MARKS
There shall be a maximum of 40 Internal Assessment Marks in each practical papers,
the IA marks shall be based on the laboratory journals/reports and one practical test.
A candidate failing to secure a minimum of 50% of the IA marks (20/40) in Practical,
50% of marks in project work, shall not be eligible for the practical / project in the
University examination. For a pass in a Practical/Project/Viva-voce examination, a
candidate shall secure a minimum of 40% of the maximum marks prescribed for the
University Examination in the relevant Practical/Project/Viva-voce.
GLOBAL ACADEMY OF TECHNOLOGY
vii Dept. of Civil Engineering Basic Surveying Practice Manual - 17CVL38
BASIC SURVEYING PRACTICE
[As per Choice Based Credit System (CBCS) scheme]
SEMESTER – III
Subject Code : 17CVL38 CIE Marks : 40
No. of Practical Hrs / Week : 03(1 hour instruction + 2 hours lab) Exam Hours : 03
Total No. of Practical Hrs. : 40 SEE Marks : 60
Sl.No. Modules TeachingHours
1.
a) Measurements of distances using tape along with horizontal planes and
slopes, direct ranging. b) Setting out perpendiculars. Use of cross staff,
optical square
03
2. Obstacles in chaining and ranging – Chaining but not ranging, ranging but
not chaining, both ranging and chaining. 03
3. Measurements of bearings / directions using prismatic compass, setting of
geometrical figures using prismatic compass. 03
4. Measurement of bearings of sides of a closed traverse and adjustment of
closing error by Bowditch method. 03
5. Determination of distance between two inaccessible points using compass
and accessories 03
6. Determination of reduced levels of points using dumpy level/auto level
(simple leveling) 03
7. Determination of reduced levels of points using dumpy level/auto level
(differential leveling and inverted leveling) 03
8. To determine the difference in elevation between two points using
Reciprocal leveling and to determine the collimation error 03
9.
To conduct profile leveling, cross sectioning and block leveling. Plotting
profile and cross sectioning in excel. Block contour on graph paper to
scale
03
10. Measurement of horizontal angle by repetition and reiteration methods
and Measurement of vertical angles using theodolite. 03
11.
Determination of horizontal distance and vertical height to a base
inaccessible object using theodolite by single plane and double plane
method.
03
12. To determine distance and elevation using tachometric surveying with
horizontal and inclined line of sight. 03
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viii Dept. of Civil Engineering Basic Surveying Practice Manual - 17CVL38
Sl.No. Modules TeachingHours
13. Closed traverse surveying using Theodolite and applying corrections for
error of closure by transit rule. 03
14. Demonstration of Minor instruments Clinometer, Ceylon Ghat tracer, Box
sextant, Hand level, Planimeter, nautical sextant and Pentagraph 03
Reference Books:
1. S.K. Duggal, “Surveying Vol.1”, Tata McGraw Hill Publishing Co. Ltd. NewDelhi. – 2009.
2. K.R. Arora, “Surveying Vol. 1” Standard Book House, New Delhi. – 2010
GLOBAL ACADEMY OF TECHNOLOGY
ix Dept. of Civil Engineering Basic Surveying Practice Manual - 17CVL38
COURSE OUTCOME
Upon successful completion of this course, students should be able to:
KL-Knowledge Level, U- Understand, Ap-Apply
Subject code: 17CVL38 Subject: BASIC SURVEYING PRACTICE
COs COURSE OUTCOMES KL No. of
sessions
CO1
Apply the basic principles of engineering surveying for linear and
angular measurements. Ap 20
CO2
Comprehend effectively field procedures required for a professional
surveyor. Ap 17
CO3
Use techniques, skills and conventional surveying instruments necessary
for engineering practice.
U
3
GLOBAL ACADEMY OF TECHNOLOGY
x Dept. of Civil Engineering Basic Surveying Practice Manual - 17CVL38
EVALUATION SCHEME
VTU LAB EVALUATION PROCESS
WEEK WISE VALUATION OF EACH EXPERIMENT
SL.NO ACTIVITY MARKS
2017 SCHEME
1 Write up 5
2
Conduction (7 – Field
Conduction + 3 – Lab
Instruction)
10
TOTAL 15
FINAL INTERNAL ASSESSMENT CALCULATION
SL.NO ACTIVITY MARKS
2017 SCHEME
1 Average of Weekly Entries 30
2 Internal Assessment Reduced To 10
TOTAL 40
INTERNAL ASSESSMENT EVALUATION (End of Semester)
SL.NO ACTIVITY MARKS
2015 SCHEME
1 Write-Up 9
2 Conduction 42
3 Viva Voce 9
TOTAL 60
GLOBAL ACADEMY OF TECHNOLOGY
xi Dept. of Civil Engineering Basic Surveying Practice Manual - 17CVL38
CONTENTS
LABORATORY CERTIFICATE _______________________Error! Bookmark not defined.
PROPROGRAM EDUCATION OBJECTIVES-PEO’s ______________________________ iii
PROGRAM OUTCOMES-PO’s ________________________________________________ iii
PROGRAM SPECIFIC OUTCOMES-PSO’s ______________________________________ iv
PREFACE _________________________________________________________________ v
COURSE OUTCOME ________________________________________________________ ix
EVALUATION SCHEME_____________________________________________________ x
CONTENTS ________________________________________________________________ xi
GENERAL INSTRUCTIONS _________________________________________________ xiv
LIST OF EXPERIMENTS ____________________________________________________ xv
IMPORTANCE OF BASIC SURVEYING PRACTICE ____________________________ xvi
EXPERIMENT 1- ___________________________________________________________ 1
a) Measurement of distances using tape along horizontal planes and slopes, direct/indirect
ranging,____________________________________________________________________ 1
b) Setting out perpendiculars. Use of cross staff, optical square. ______________________ 1
Measurement of Distance ________________________________________________ 1
Measurement of Distance on Slopping Ground _______________________________ 4
Setting Out of Perpendiculars ____________________________________________ 6
EXPERIMENT 2- Obstacles in chaining and ranging – Chaining but not ranging, ranging but
not chaining, both ranging and chaining. __________________________________________ 9
Obstacle to Ranging but Not Chaining _____________________________________ 9
Obstacle to Chaining but Not Ranging ____________________________________ 10
Obstacle to Both Chaining and Ranging ___________________________________ 13
EXPERIMENT 3- Measurement of bearings/directions using prismatic compass, setting of
geometrical figures using prismatic compass ______________Error! Bookmark not defined.
EXPERIMENT 4- Measurement of bearings of sides of a closed traverse and adjustment of
closing error by Bowditch method. _____________________________________________ 22
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xii Dept. of Civil Engineering Basic Surveying Practice Manual - 17CVL38
EXPERIMENT 5 - Determination of distance between two inaccessible points using compass
and accessories _____________________________________________________________ 26
EXPERIMENT 6 - Determination of reduced levels of points using dumpy level/auto level
(simple leveling). ___________________________________________________________ 29
Determination of RL of an object above the plane of collimation using inverted leveling. __ 35
EXPERIMENT 8 - To determine the difference in elevation between using reciprocal leveling
and to determine the collimation error ___________________________________________ 36
EXPERIMENT 9 - To conduct profile leveling, cross sectioning and block leveling. Plotting
profile and cross sectioning in excel. Block contour on graph paper to scale _____________ 38
Profile Levelling______________________________________________________ 38
Cross Sectioning _____________________________________________________ 41
Block leveling, preparation of contour plan using excel. Use of planimeter/graph and
computations of Areas and volumes. ____________________________________________ 44
Block Levelling ______________________________________________________ 44
Contouring __________________________________________________________ 46
EXPERIMENT 10- Measurement of horizontal angle by repetition and reiteration methods and
measurement of vertical angles using theodolite ___________________________________ 47
Method of Repetition __________________________________________________ 47
Measurement of Horizontal Angle-Method of Reiteration _____________________ 51
Measurement of vertical angles using theodolite. __________________________________ 54
EXPERIMENT 11-Determination of horizontal distance and vertical height to a base
inaccessible object using theodolite by single plane and double plane method. ___________ 57
EXPERIMENT 12- to determine distance and elevation using tacheometric surveying with
horizontal and inclines line of sight. ____________________________________________ 66
EXPERIMENT 13-Closed traverse surveying using theodolite and applying corrections for
error of closure by transit rule. _________________________________________________ 70
EXPERIMENT 14 - Demonstration of minor instruments ___________________________ 73
Hand Level __________________________________________________________ 73
Box Sextant _________________________________________________________ 74
Clinometer __________________________________________________________ 75
Ceylon Ghat Tracer ___________________________________________________ 76
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xiii Dept. of Civil Engineering Basic Surveying Practice Manual - 17CVL38
Planimeter __________________________________________________________ 77
Pentagraph __________________________________________________________ 79
Additional Exercise _________________________________________________________ 81
Viva-Voce ________________________________________________________________ 82
Linear Measurements __________________________________________________ 82
Chain Surveying ______________________________________________________ 82
Compass Traversing ___________________________________________________ 83
Levelling ___________________________________________________________ 83
Theodolite Traversing _________________________________________________ 84
Tacheometric Survey __________________________________________________ 85
GLOBAL ACADEMY OF TECHNOLOGY
xiv Dept. of Civil Engineering Basic Surveying Practice Manual - 17CVL38
GENERAL INSTRUCTIONS
1. Students should be regular to the lab.
2. Shoe, Apron, Observation book, Manual, and Calculator and water bottle are must before
entering the lab.
3. Failure to bring the observations and record regularly will result in deduction in 1 mark
every week.
4. List of instruments are to be entered in the issue register before taking it to the field.
5. Instruments are to be returned strictly to the lab instructors only.
6. The instruments should be checked at the time of issue and return.
7. The instrument should be replaced by a new one in case of damage/missing.
8. The instrument should not be left unattended in the field.
9. The instruments should be protected from sun, rain and dust.
10. Tape/chain should be read correctly while measuring distances.
11. Arrows must be fixed at the end of chain line firmly.
12. The compass box must be tapped gently after the needle comes to rest.
13. The vibrations of the magnetic needle should be stopped by gently pressing the knob.
14. The compass/level should be set up on firm ground properly and all the temporary
adjustments should be made before taking the observations.
15. Iron and steel articles should be avoided near the compass.
16. The bubble should be checked before and after taking staff reading.
17. The tripod should not be disturbed by resting hands on it.
18. During high winds leveling work should be stopped.
19. The line of sight should be quite high above the ground.
20. Proper care should be taken in selecting change points.
21. The reading should be recorded properly and neatly.
22. The level should not be lifted by telescope.
23. The lenses should not be touched with hands.
24. The leveling screws should not be over tightened.
25. The level should be placed properly in the box.
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xv Dept. of Civil Engineering Basic Surveying Practice Manual - 17CVL38
LIST OF EXPERIMENTS E
xp
erim
ent
No.
Date
of
Con
du
ctio
n
Experiments Page
No.
1 a) Measurements of distances using tape along with horizontal
planes and slopes, direct ranging.
b) Setting out perpendiculars. Use of cross staff, optical square
2 Obstacles in chaining and ranging – Chaining but not ranging,
ranging but not chaining, both ranging and chaining.
3 Measurements of bearings / directions using prismatic compass,
setting of geometrical figures using prismatic compass.
4 Measurement of bearings of sides of a closed traverse and
adjustment of closing error by Bowditch method.
5 Determination of distance between two inaccessible points using
compass and accessories
6 Determination of reduced levels of points using dumpy
level/auto level (simple leveling)
7 Determination of reduced levels of points using dumpy
level/auto level (differential leveling and inverted leveling)
8 To determine the difference in elevation between two points
using Reciprocal leveling and to determine the collimation error
9 To conduct profile leveling, cross sectioning and block leveling.
Plotting profile and cross sectioning in excel. Block contour on
graph paper to scale
10 Measurement of horizontal angle by repetition and reiteration
methods and Measurement of vertical angles using theodolite.
11 Determination of horizontal distance and vertical height to a base
inaccessible object using theodolite by single plane and double
plane method.
12 To determine distance and elevation using tachometric surveying
with horizontal and inclined line of sight.
13 Closed traverse surveying using Theodolite and applying
corrections for error of closure by transit rule.
14 Demonstration of Minor instruments Clinometer, Ceylon Ghat
tracer, Box sextant, Hand level, Planimeter, nautical sextant and
Pentagraph
GLOBAL ACADEMY OF TECHNOLOGY
xvi Dept. of Civil Engineering Basic Surveying Practice Manual - 17CVL38
IMPORTANCE OF BASIC SURVEYING PRACTICE
The planning and design of all Civil Engineering projects such as construction of
highways, bridges, tunnels, dams etc are based upon surveying measurements.
Moreover, during execution, project of any magnitude is constructed along the lines and
points established by surveying.
Thus, surveying is the basic requirement for all Civil Engineering projects.
Other principal works in which surveying is primarily utilized is;
To fix the national and state boundaries.
To chart coastlines, navigable streams and lakes.
To establish control points.
To execute hydrographic and oceanographic charting and mapping.
To prepare topographic map of land surface of the earth.
GLOBAL ACADEMY OF TECHNOLOGY
1 Dept. of Civil Engineering Basic Surveying Practice Manual - 17CVL38
EXPERIMENT 1-
a) Measurement of distances using tape along horizontal planes and slopes,
direct/indirect ranging,
b) Setting out perpendiculars. Use of cross staff, optical square.
Measurement of Distance
AIM: To measure distance between two points using tape bydirect ranging.
INSTRUMENTS REQUIRED
a) Chain or tape,
b) Ranging rods,
c) Arrows.
THEORY
The process of measuring the distance using chain or tape is called Chaining. While
measuring the length of a survey line, chain or tape must be stretched straight along the line
joining two terminal stations. When the length of the line exceeds the length of a tape, some
intermediate points will have to be established in line with the two terminal points before
chaining is started. This process of establishing such intermediate points is known as
Ranging. Direct ranging is done when two end points of the survey lines are intervisible. In
such cases ranging can either be done by eye or through some optical instrument such as line
ranger or a theodolite.
Fig.1.1: Direct Ranging
PROCEDURE
1.Let the length of a line AB is to be measured, Point ‘A’ being the starting point.
2.Erect two ranging rods vertically at ‘A’ and ‘B’.
3.The surveyor stands about half meter behind the ranging rod at ‘A’ in line with ‘AB’.
4.The assistant then goes with another ranging rod and establishes the rod at a point
approximately in line with ‘AB’ (by judgment) at a distance not greater than one chain
length from ‘A’.
GLOBAL ACADEMY OF TECHNOLOGY
2 Dept. of Civil Engineering Basic Surveying Practice Manual - 17CVL38
Fig.1.2: Field conduction of Direct Ranging
5.The surveyor at ‘A’ directs the assistant to move the ranging rod till it is in line with
‘AB’. The code of signals used for this purpose is given in the table below:
SL.
NO.
Signal by the Surveyor
Action by the assistant
1 Rapid sweep with right hand Move considerably to the right
2 Slow sweep with right hand Move slowly to the right
3 Right arm extended Continue to move to the right
4 Right arm up and moved to the right Plumb the rod to the right
5 Rapid sweep with left hand Move considerably to the left
6 Slow sweep with left hand Move slowly to the left
7 Left arm extended Continue to move to the left
8 Left arm up and moved to the right Plumb the rod to the left
9 Both the hands above head and then brought down Correct
10 Both the arms extended forward horizontally and
the hands depressed briskly Fix the rod
6.Similarly establish some intermediate stations by direct ranging.
7.The follower stands at the point ‘A’ holding one end of the tape while the leader moves
ahead holding zero end of the tape in one hand and a bundle of arrows in the other. When
he reaches approximately one tape length distance from ‘A’, the follower directs him for
ranging in the line.
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3 Dept. of Civil Engineering Basic Surveying Practice Manual - 17CVL38
8.The tape is then pulled out and whipped gently to make sure that its entire length lies
along the line.
9.The leader then pushes the arrow into the ground, opposite the zero.
10.When the second arrow has been established by the leader, the follower picks up the
first arrow and both the persons move ahead as described in the step7, 8 and 9.
11.At the end of the line (at B) the last measurement will generally be a partial tape length.
The leader holds the zero end of the tape at ’B’ while the follower pulls the tape back till it
becomes taut and then reads against the arrow.
OBSERVATIONS & CALCULATIONS
Total distance measured = ………………….
Number of Paces = …………………………..
Pace value = =
RESULT:
Practical Application: (List any two practical scenario)
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4 Dept. of Civil Engineering Basic Surveying Practice Manual - 17CVL38
Measurement of Distance on Slopping Ground
Chaining on slopping ground
a) Direct method (Method of Stepping)
Fig.1.3: Measurement on Sloping Ground – Method of Stepping
1. Let it be required to measure the horizontal distance between the two points A and B.
2. The follower holds the zero end of the tape at A while the leader selects any suitable
length l1 of the tape and moves forward. The follower directs the leader for ranging.
3. The leader pulls the tape tight, makes it horizontal and the point 1 is then transferred to
the ground by a plumb bob. Sometimes, a special form of drop arrow is used to transfer
the point to the surface, as shown in figure above.
4. The procedure is then repeated. The total horizontal distance D between the two points
is then equal to l1+ l2+ l3+ l4+……….
5. The lengths l1, l2 etc., to be selected depend on the steepness of slope. Steeper the
slope, lesser the length and vice versa.
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5 Dept. of Civil Engineering Basic Surveying Practice Manual - 17CVL38
b) Indirect method
i. Angle measured
Fig.1.4: Clinometer
Fig.1.5: Indirect Method – Angle Method
1. Measure the inclined distances l1, l2 etc.
2. The slopes of the lines (𝜃1,𝜃2 etc.) with the help of clinometers.
3. The total horizontal distance D between the two points is then equal to ∑ 𝑙𝑖 cos 𝜃𝑖
ii. Difference in level measured
Fig.1.6: Indirect Method – Difference in Level Measured
1. The difference in the level (h) between the points is measured with the help of
levelling instrument.
2. The inclined length l is measured.
3. The total horizontal distance D between the two points is then equal to √ℎ2 + 𝑙2
RESULT:
Practical Application: (List any two practical scenario):
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6 Dept. of Civil Engineering Basic Surveying Practice Manual - 17CVL38
Settingout of Perpendiculars
AIM: To set out perpendiculars to a given chain line using cross staff, optical square and tape.
INSTRUMENTS REQUIRED:
a. Tape or chain
b. Ranging rods
c. Arrows
d. Cross staff
e. Optical square.
THEORY:
There are several types of instruments used to set out a right angle to a chain line. The
most common being cross staff, optical square and prism square. The simplest instrument
used for setting out right angle is a cross staff. It consists of either a frame or box with two
pairs of vertical slits and is mounted on a pole for fixing in the ground. The common forms of
cross staff areopen cross staff, French cross staff, and adjustable cross staff. Optical square
is somewhat more convenient and accurate instrument than the cross staff for setting out a line
at right angles to another line. It consists of a circular box with three slits at E, F, and G. in
line with the openings E and G, a glass silvered at the top and unsilvered at the bottom, is
fixed facing the opening E. Opposite to the opening F, a silver glass is fixed at A making an
angle of 45º to the previous glass. A ray from the ranging rod at Q passes through the lower
unsilvered portion of the mirror at B and is seen directly by eye at the slit E. Another ray from
the object at P is received by the mirror at A and is reflected towards the mirror at B which
reflects it towards the eye. Thus the images of P and Q are visible at B, if both the images are
in the same vertical line.
PROCEDURE:
I. Setting out perpendicular using Optical Square:
To set a right angle on a survey line, the instrument is held on the line with its centre
on the point at which perpendicular is erected. The slits F and G are directed towards
the ranging rod fixed at the end of the line. The surveyor (holding the instrument) then
directs person holding a ranging rod and standing in a direction roughly perpendicular
to the chain line, to move till the two images described above coincide.
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7 Dept. of Civil Engineering Basic Surveying Practice Manual - 17CVL38
Fig.1.7: Optical Square and field procedure to set out perpendicular
II. Setting out perpendicular using cross staff:
Fig.1.8: Cross staff
1. The cross staff is set up at a point on the line where perpendicular is to be set out.
2. The cross staff is turned until one line of sight bisects the ranging rod at the end of the
survey line.
3. The line of sight through the other slit will be at right angle to the survey line and
ranging rod may be established in that direction.
III. Setting out perpendicular using tape:
Fig.1.9: Methods of Setting Out Perpendiculars
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Let it be required to erect a perpendicular to the chain line AB at a point C.
3-4-5 method
1. Establish a point E at a distance 3m from C.
2. Put the zero end of the tape at E and the 10m end at C. The 5m and 6m marks are
brought together to form a loop of 1m.
3. The tape is now stretched tight fastening the ends E and C. The point D is thus
established. CD will be perpendicular to AB.
Second method
1. Select E and F equidistance from C.
2. Hold the zero end of the tape at E and 10m end at F.
3. Pick up 5m mark, stretch the tape tight and establish D. Join DC.CD will be
perpendicular to AB.
To drop a perpendicular to a given chain line from a point outside it
1. Select any point E on the line AB.
2. With D as center and DE as radius, draw an arc to cut the chain line in F.
3. Bisect EF at C. CD will be perpendicular to AB.
RESULT: The perpendiculars are set out successively in the field.
Practical Application: (List any two practical scenario):
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9 Dept. of Civil Engineering Basic Surveying Practice Manual - 17CVL38
EXPERIMENT 2- Obstacles in chaining and ranging – Chaining but not ranging, ranging
but not chaining, both ranging and chaining.
Obstacle to Ranging but Not Chaining
AIM: To range and measure the distance between two points which is having obstacle to
ranging but not chaining.
INSTRUMENTS REQUIRED:
a. Chain or tape
b. Ranging rods
c. Arrows
d. Cross staff.
THEORY
There may be two cases of this obstacle.
a) Both ends of the line may be visible from intermediate points on the line – Reciprocal
ranging or indirect ranging.
Fig.2.1: Indirect Ranging – Reciprocal Ranging
b) Both ends of the line may not be visible from intermediate points on the line.
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Fig.2.1: Indirect Ranging: When Both Ends Not Visible from Intermediate Points
PROCEDURE
1. Let AB be the line in which A and B are not visible from intermediate point on it.
2. Through A, draw a random line AB1in any convenientdirection but as nearly towards B
as possible.
3. The point B1should be chosen in such a way that it is visible from B and BB1 is
perpendicular to the random line. Measure BB1.
4. Select points C1and D1 on the random line and erect perpendicular C1C=𝐴𝐶1
𝐴𝐵1𝑋𝐵𝐵1 and
D1D= 𝐴𝐷1
𝐴𝐵1𝑋𝐵𝐵1on it.
Obstacle to Chaining but Not Ranging
AIM: To range and measure the distance between two points which is having obstacle to
chaining but not ranging.
INSTRUMENTS REQUIRED
a. Chain or tape
b. Ranging rods
c. Arrows
d. Cross staff
e. Optical square.
THEORY
There may be two cases of this obstacle:
a) When it is possible to chain round the obstacle, i.e. a pond, hedge etc.
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b) When it is not possible to chain round the obstacle, i.e. a river.
PROCEDURE
A. When it is possible to chain round the obstacle
Method (a):
1. Select two points A and B on either side.
2. Set out equal perpendiculars AC and BD shown
in [fig. (a)]. Measure CD=AB.
Method (b):
1. Set out AC perpendicular to the chain line.
Measure AC and BC [fig.(b)]
2. The length AB is calculated from the relation
AB=√𝐵𝐶2 − 𝐴𝐶2.
Method (c):
1. By optical square or cross staff, find a point C
which subtends 90º with A and B.
2. Measure AC and BC [fig.(c)]. The length AB is
calculated from the relation AB=√𝐴𝐶2 + 𝐵𝐶2.
Method (d):
1.Select two points C and D on either side of A in the same
line.
2.Measure AC, AD, BC and BD [fig.(d)].
3.Let angle BCD be equal to 𝜃.
cos 𝜃= 𝐵𝐶2+𝐴𝐶2−𝐴𝐵2
2𝑋𝐵𝐶𝑋𝐴𝐶
4.The length AB is calculated from the relation
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𝐴𝐵 = √(𝐵𝐶2𝑋𝐴𝐷)+(𝐵𝐷2𝑋𝐴𝐶)
𝐶𝐷− (𝐴𝐶𝑋𝐴𝐷)
Method (e):
1. Select any point E and range C in line with AE,
making AE= EC.
2. Range D in line with BE and make BE=ED.
Measure CD=AB [fig.(e)].
Method (f):
1. Select any suitable point E and measure AE and BE.
Mark C and D on AE and BE such that CE=𝐴𝐸
𝑛 and DE =
𝐵𝐸
𝑛 .
2. Measure CD. AB= n XCD [fig.(f)].
B. When it is not possible to chain round the obstacle
Method (a):
1. Select point B on one side and A and C on the other
side. Erect AD and CE as perpendiculars to AB and range B, D and
E in one line.
2. Measure AC, AD and CE [fig.(a)].
3. If a line DF is drawn parallel to AB, cutting CE in F
perpendicularly. The triangles ABD and FDE will be similar.
𝐴𝐵 =𝐴𝐶𝑋𝐴𝐷
𝐶𝐸 − 𝐴𝐷
Method (b):
1.Erect a perpendicular AC and bisect it at D.
2.Erect perpendicular CE at C and range E in line with BD.
3.Measure CE =AB [fig.(b)].
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Method (c):
1.Erect a perpendicular AC at A and choose any convenient point C.
2. With the help of an optical square, fix a point D on the chain line in
such a way that BCD is a right angle [fig.(c)].
3.Measure AC and AD.
4.The triangles ABC and DAC will be similar.
𝐴𝐵 =𝐴𝐶2
𝐴𝐷
Method (d):
1.Fix point C in such a way that it subtends 90º with AB.
2.Range D in line with AC and make AD=AC.
3.At D, erect a perpendicular DE to cut the line in E [fig.(d)].
Then AB=AE.
Obstacle to Both Chaining and Ranging
AIM: To range and measure the distance between two points which is having obstacle to both
chaining and ranging.
INSTRUMENTS REQUIRED:
a. Chain or tape
b. Ranging rods
c. Arrows
d. Cross staff.
THEORY:
A building is the typical example of this type of obstacle. The problem lies in
prolonging the line beyond the obstacle and determining the distance across it.
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PROCEDURE
Method (a):
1.Choose two points A and B to one side and erect
perpendiculars AC and BD of equal length.
2.Join CD and prolong it. Choose two points E and F on CD
and erect perpendiculars EG and FH equal to that of AC.
3.Join GH and prolong it. Measure DE=BG [fig.(a)].
Method (b):
1.Select a point A and erect a perpendicular AC of any
convenient length.
2.Select another point B on the chain line such that
AB=AC. Join B and C and prolong it to any convenient
point D. At D set right angle DE such that DE=DB.
3.Choose another point F on DE such that DE=DC.
With F as centre and AB as radius, draw an arc. With E as centre, draw another arc of
same radius to cut the previous arc in G.
4.Join GE which will be in range with the chain line. Measure CF. the AG=CF [fig.(b)].
Method (c):
1. Select two points A and B on the chain line and construct an
equilateral triangle ABE by swinging arcs. Join AE and produce it
to any point F.
2. On AF, choose any point H and construct an equilateral
triangle FHK.
3. Join F and K and produce it to D such that FD=FA.
4. Choose a point G on FD and construct an equilateral triangle CDG.
5. The direction CD is in range with the chain line [fig.(c)].
6. The length BC is given by
BC=AD-AB-CD=AF-AB-CD
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Method (d):
1.Select two points A and B on the chain line and set a
line CBD at any angle.
2.Join A and C and produce it to F such that AF
=nXAC.
3.Similarly join A and D and produce it to G such that
AG= nXAD.
4.Join F and G and mark point E on it such that
FE=nXBC.
5.Similarly, produce AF and AG to H and K respectively such that AH=nlXAC and AK=
nlXAD.
6.Join H and K and mark J on it in such a way that HJ= nlXCB.
7.Join EJ, which be in range with chain line.
8.The obstructed distance BE [fig.(d)].is given by
BE= (n-1)AB
OBSERVATIONS & CALCULATIONS:
A. When it is possible to chain round the obstacle
Method (a):
Method (b):
Method (c):
Method (d):
Method (e):
Method (f):
B. When it is not possible to chain round the obstacle
Method (a):
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Method (b):
Method (c):
Method (d):
RESULT: The distance between two points is found to be = ________ m.
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EXPERIMENT 3- Measurement of bearings/directions using prismatic compass, setting of
geometrical figures using prismatic compass.
CASE 1: RECTANGLE/SQUARE
AIM: To set out a regular rectangle of side AB=20m and BC=15m using compass and chain
given the bearing of AB is α = 68030’
APPARATUS:
a) Prismatic compass,
b) ranging rods,
c) arrows,
d) Tape etc.
THEORY: The included angle of geometrical figure is given by the angle
θ = [2n-4]*90o/n
θ = included angle
θ = [2*4-4]*90o/4
θ = 90 o
Line Fore Bearing Back Bearing Length
AB 68030’ 248030’ 30
BC 338030’ 158030’ 20
CD 248030’ 68030’ 30
DA 158030’ 338030’ 20
PROCEDURE:
1) With the given bearing of AB = 68030’ and the condition that the angles of a rectangle
are equal to 900, the bearings of the sides BC, CD and DA are computed and entered in
the table shown.
2) In the field, a station A is selected and the compass is setup over A. after centering and
levelling, the bearing of 68030’ is set on the compass.Thus, the direction of the line AB
is obtained and a ranging rod is fixed in that direction.
3) From A, a distance of 30 m is measured and station B is marked.
4) The compass is shifted to B and after centering and levelling. The station A is
observed to check the BB of the line AB which should be equal to 248030’.
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5) The bearing of the next line BC, 338030’ is set on the compass and the direction of the
line BC is obtained and a ranging rod is fixed at a convenient distance.
6) From B a distance of 20 m is measured along this direction and station C is marked on
the ground.
7) Steps 4, 5 and 6 is repeted to set the remaining points on the ground.
Fig.3.1: Setting up of Rectangle
Observation and Calculation:
Given that,
Bearing of AB = --------
Assuming traversing is done in anticlockwise direction.
We have,
a) Bearing of BC= BB of AB+ Included angle = -----------
b) Bearing of CD = BB of BC + Included angle = -----------
c) Bearing of DA = BB of CD + Included angle= -----------
Check:Bearing of AB= BB of DA + Included angle = -----------
Theoretical Parameters:Sides AB+BC+CD+DA = ------m
Practical Parameters:Sides AB+BC+CD+DA =-------m
% of error in DC= Theoretical value –Practical value X100 = -------%
Theoretical value
RESULT:A rectangle of sides 15m & 20m is constructed by using a prismatic compass.
The linear error is -----------m &Angular error is -------------
20 m 30 m
B
A
C
D
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CASE 2: PENTAGON
AIM: Construct a regular pentagon of side AB=6m using compass
APPARANTIS:
a) Prismatic Compass,
b) Ranging rod,
c) Arrows,
d) Tape.
PROBLEM: To construct a regular pentagon ABCDE taking the length of side as 6m &
bearing of AB as 30o30’.
THEORY: The included angle of any geometrical figure is given by
θ = [2n-4]*90o/n
Where n = No of sides.
θ = Included angle.
θ = [2*5-4]*90o/5
θ = 108 o
PROCEDURE:
1) Set out the compass at station A & make temporary adjustments. The line of sight is
turned to set the bearing as 30o30’ long, this line of sight mark a point B at a distance of
6m.
2) Shift the compass to point B and make the temporary adjustments. The back bearing of
AB is noted as a check the line of sight is turned to set the bearing of line BC along the
line of sight mark a point C along a distance of 6m.
3) Now the compass is shifted to point c to set the bearing of line as 174o 30’along this
line of sight mark a point D at a distance of 6m.
4) Now the compass is shifted to point C, to set the bearing of line as 174o30’along this
line of sight mark a point D at a distance of 6m.
5) The same procedure is repeated at a corresponding points D&E & corresponding
bearings are locked and the points are marked as check, measure the distance of EA.
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Fig.3.2: Setting up of Pentagon
OBSERVATION AND CALCULATION
Interior angle of Pentagon,
I.A = θ = [2n-4]*90o/nI.A = ---------------
Assuming traversing is done in clockwise direction.
We have,
a) FB of line AB= ---------- B.B of line AB = -----------
b) FB of line BC = BB of line AB – Interior angle =-------------
B.B of line BC = -----------
c) FB of line CD = BB of line BC – Interior angle=-------------
B.B of line CD = -----------
d) FB of line DE = BB of line CD – Interior angle =-------------
B.B of line DE = -----------
e) FB of line EA = BB of line DE – Interior angle=-------------
B.B of line EA = -----------
Check:FB of line AB = BB of line EA – Interior angle =-------------
Line Fore Bearing Back Bearing Length obtained
Std Obtained
AB
BC
CD
DA
EA
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RESULT: A regular pentagon of side 6m is constructed using a prismatic compass.
Linear Error Is ------M
Angular Error Is -----M
CASE 3: HEXAGON
AIM: Construct a regular hexagon of side AB=6m with the FB of AB is N30oE.
APPARATUS:
a) prismatic compass,
b) ranging rod,
c) arrows,
d) tape etc.,
THEORY: The included angle of any geometrical figure is give by
θ = [2n-4]*90o/n
Where n = no of sides,
θ = included angle
θ = [2*6-4]*90o/6
θ = 120 o
PROCEDURE:
Exterior angle =360-120=240o Included angle=120o.
1) Set out the compass at station A & make temporary adjustments. The line of sight is
turned to set the bearing as 30o along this line of sight mark a point B at a distance of 6m.
2) Shift the compass to point B and make the temporary adjustments. The back bearing of
AB is noted as a check, the line of sight is turned, to set the bearing of line BC along the
line of sight mark a point C at a distance of 6m.
3) Now the compass is shifted to point C, to set the bearing of line as 150o, along this line
of sight mark a point D at a distance of 6m.
4) The same procedure is repeated at a corresponding points D, E&F, corresponding
bearings are located and the points are marked, as a check measure the distance of FA.
OBSERVATION AND CALCULATION
Interior angle of Pentagon,
I.A = θ = [2n-4]*90o/nI.A = ---------------
Assuming traversing is done in clockwise direction.
We have,
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1. FB of line AB= ---------- B.B of line AB = -----------
2. FB of line BC = BB of line AB – Interior angle =-------------
B.B of line BC = -----------
3. FB of line CD = BB of line BC – Interior angle =-------------
B.B of line CD = -----------
4. FB of line DE = BB of line CD – Interior angle =-------------
B.B of line DE = -----------
5. FB of line EF = BB of line DE – Interior angle =-------------
B.B of line EF = -----------
6. FB of line FA = BB of line EF – Interior angle =-------------
B.B of line FA = -----------
Check:
7. FB of line AB = BB of line FA – Interior angle.
=-------------
Line Fore Bearing Back Bearing Length obtained
Std Obtained
AB
BC
CD
DA
EA
FA
RESULT: Thus a regular hexagon of sides 6m is constructed using compass.
Linear error is ------m
Angular error is -------
EXPERIMENT 4- Measurement of bearings of sides of a closed traverse and adjustment of
closing error by Bowditch method.
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AIM: To measure the bearings of the sides of the closed traverse and adjustment of the
closing error by Bowditch method.
INSTRUMENTS REQUIRED:
a. Prismatic compass with stand
b. Chain/tape
c. Ranging rods
d. Arrows.
THEORY:
A ‘traverse’ is a frame formed by a series of connected straight lines, none of which is
connected at each of its ends to lines more than one. The points defining the ends of the
traverse line are called traverse stations or traverse points. When the lines form a circuit which
ends at the starting point is known as a closed traverse. If the circuit ends elsewhere, it is said
to be an open traverse. Closed traverse is suitable for locating boundaries of lakes, forests
etc. Open traverse is suitable for surveying along long narrow strip of land required for a road
or canal or pipeline or the coast line.
In compass traversing, the magnetic bearing of the survey lines are measured by a
compass and the length of the survey lines are measured either with a chain or with a tape.
The direction of magnetic meridian is established at each traverse station independently. The
method is also known as free or loose needle method. The latitude (L) of survey line may be
defined as its coordinate length measured parallel to the assumed meridian direction. The
latitude of the line is positive when measured northward (upward) and is termed as northing.
The latitude of the line is negative when measured southward (downward) and is termed as
southing.Thedeparture (D) of survey line may be defined as its coordinate length measured
right angles to the assumed meridian direction. The departure of the line is positive when
measured eastward and is termed as easting. The departure of the line is negative when
measured westward and is termed as westing.
Closing error or error of closure is the actual distance by which the traverse fails to
close. Bowditch method is also known as compass rule. In this method the total error in
latitude and departure is distributed in proportion to the lengths of the traverse lines. It is used
to balance the traverse when the angular and linear measurements are equally precise. Transit
method may be employed to balance the traverse when the angular measurements are more
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precise than the linear measurements. In this method the total error in latitude and departure is
distributed in proportion to the latitude and departure of the traverse lines.
Fig.4.1: Closing Error
FORMULAE
Bowditch method:
CL= ∑𝑳𝑿𝒍
∑ 𝒍
CD= ∑𝑫𝑿𝒍
∑ 𝒍
Where CL= Correction to latitude of any side
CD= Correction to departure of any side
𝑙= Length of that side
∑ 𝑙= Perimeter of traverse
∑ 𝐿= Total error in latitude
∑ 𝐷= Total error in departure
PROCEDURE:
1. Let A, B, C, D, E are the traverse stations.
2. Set the compass at station ‘A’ and take the fore bearing of the line AB. Measure the
distance AB.
3. Now shift the instrument to the station ‘B’, take the bearing of the line BC. Also tale
the back bearing of line AB, measure the distance BC.
4. Similarly the length and bearing of each line of the traverse is to be measured.
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OBSERVATIONS & CALCULATIONS
Bowditch method
SL.
NO.
Line Length
(𝑙)in m
Bearing Latitude
L=𝑙𝐶𝑜𝑠𝜃
Departure
D=𝑙𝑆𝑖𝑛𝜃
Corrections Corrected
Latitude Departure Latitude Departure
1
2
3
4
5
6
∑ 𝑙= …………….∑ 𝐿= ……………
∑ 𝐷= ……………
RESULT:
Practical Application: (List any two practical scenario):
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EXPERIMENT5 - Determination of distance between two inaccessible points using
compass and accessories
AIM: To find the distance between two inaccessible points using Compass, Tape etc.
APPARATUS:
a. Tape
b. Arrows
c. Prismatic Compass with stand.
THEORY: The method is based on the trigonometric proposition of
i. Sine rule: That, if one side and three angles of a triangle are known then, the third
side of a triangle can be calculated.
ii. Cosine rule: that, if two sides of a triangle and included angle between them is
known, then the third side of a triangle can be calculated.
Thus, on a known base length CD, the directions of two inaccessible points A and B are
observed by Prismatic compass from two stations C and D. The angle between the lines CA,
CB, CD and DA, DB, DC is then computed and using rule (i) and (ii), the inaccessible
distance AB can be calculated.
Fig.5.1: Measurement of Distance between Inaccessible Points
PROCEDURE:
1. Let A and B be the two inaccessible points between which the distance is to be
determined.
2. Select two points C and D at a known distance from each other
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3. Now take the instrument at station C and take the bearings to the points A, B, and D.
4. Shift the instrument to point D and take the bearing of points A, B, C.
5. The angles 1, 2, 3, 4and α and β are calculated as shown in calculation part and
the distance between A and B is calculated.
Observations:
SI No Instrument @ Side Bearing
1 C
CA
CB
CD
2 D
DC
DA
DB
Calculations:
Angle 1 = Fore bearing of CB - Fore bearing of CA
Angle 2 = Fore Bearing of CD - Fore Bearing of CB
Similarly Calculate
3 = Fore bearing of DA - Fore bearing of DC
4 = Fore bearing of DB - Fore bearing of DA
Consider Triangle ACD
∠CAD = α = 180 – (1 + 2 + 3)
Applying Sine rule:
𝐶𝐷
𝑠𝑖𝑛𝛼=
𝐴𝐶
𝑠𝑖𝑛𝜃3=
𝐴𝐷
sin( 𝜃1 + 𝜃2)
a) 𝐴𝐶 =𝐶𝐷 𝑠𝑖𝑛𝜃3
𝑠𝑖𝑛𝛼
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b) 𝐴𝐷 =𝐶𝐷 sin(𝜃1+𝜃2)
𝑠𝑖𝑛𝛼
Consider Triangle BCD
∠CBD= = 180 - ((2+3+4)
Applying Sine Rule:
𝐶𝐷
𝑠𝑖𝑛𝛽=
𝐵𝐷
𝑠𝑖𝑛𝜃2=
𝐶𝐵
sin( 𝜃3 + 𝜃4)
a) 𝐶𝐵 =𝐶𝐷 sin(𝜃3+𝜃4)
𝑠𝑖𝑛𝛽
b) 𝐵𝐷 =𝐶𝐷 𝑠𝑖𝑛𝜃2
𝑠𝑖𝑛𝛽
Considering Triangle ACB
Applying Cosine Rule
𝐴𝐵 = √(𝐴𝐶2 + 𝐵𝐶2 − 2 × 𝐴𝐶 × 𝐵𝐶 × 𝑐𝑜𝑠𝜃1)
Considering Triangle ADB
Applying Cosine Rule
𝐴𝐵 = √(𝐴𝐷2 + 𝐵𝐷2 − 2 × 𝐴𝐷 × 𝐵𝐷 × 𝑐𝑜𝑠𝜃4)
Results: The distance between two inaccessible points = ________M
Practical Application: (List any two practical scenario):
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EXPERIMENT 6 - Determination of reduced levels of points using dumpy level/auto level
(simple leveling).
AIM: To find the difference in elevation or level between any two points by using the single
set up of the instruments.
INSTRUMENTS REQUIRED:
a. Dumpy level with tripod
b. Leveling staff.
THEORY: When the difference of level between two points is determined by setting the
leveling instrument midway between the points, the process is called simple leveling.
PROCEDURE:
Fig.6.1: Simple Leveling
1. Let A&B are two points whose difference of level in to be determined.
2. Setup the instrument at ‘O’ approximately almost midway between the point A&B,
leveling by proper temporary adjustments.
3. Direct the telescope towards the staff held on a point A and make the corresponding
staff reading & record directly.
4. Hold the staff on a next point B and take the reading and enter in the field book.
5. The difference of these readings gives the difference of level between A&B
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Observation and Calculation
Station B.S I.S F.S H.I R.L Remarks
B.M
A
B
Check:
∑BS-∑FS = Last RL – First RL.
RESULTS: The difference in elevation between two points A & B is_________M
Practical Application: (List any two practical scenario):
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EXPERIMENT 7 - Determination of reduced levels of points using dumpy level/auto level
(differential leveling and inverted leveling).
AIM: To find the difference in elevation between any two points which are situated at some
distance apart by collimation system or H.I method.
APPARATUS:
a. Dumpy level with tripod
b. Leveling staff.
OBJECTIVE: The main object of differential leveling to determine the elevation between
the points when,
1. The points are a great distance apart.
2. The difference of elevation between the points is large.
3. There are obstacles between the points.
This method in also known as compound leveling or continuous leveling. In the method,
the level in setup at several suitable positions and staff reading are taken at all of these.
THEORY:
In this method the height of the instrument is found out by adding the back sight
reading to the R.L of the B.M on which the B.S is taken. Then the R.L of the intermediate
points and the change point are obtained by subtracting the respective staff reading from the
H.I.
Fig.7.1: Differential Levelling- When points are far apart
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Fig.7.2: Differential Levelling – Points with large difference of elevation
Fig.7.3: Differential Levelling – Points Having Obstacles In Between
PROCEDURE:
1. Let A&B be the two points whose difference of level is required to find.
2. Set up the instrument at point ’O1’ and after doing proper temporary adjustments
take back sight reading on a bench mark.
3. Find the height of instrument by adding B.S reading to the bench mark.
4. Take staff reading on the intermediate point like C D E &F etc.
5. Now change the instrument to the point O2 and make temporary adjustments.
6. Take the B.S reading at E& find the new H.I.
7. Take the staff reading on point F,G etc., and repeat the procedure to reach the
point ‘B’
OBSERVATION AND CALCULATION – HEIGHT OF INSTRUMENT METHOD
Station BS IS FS HI RL Remarks
B.M
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A
B
∑BS= ∑FS=
Check:
∑BS-∑FS = Last RL – First RL.
RESULT: The difference in elevation between two points A & B is ----------------M
Practical Application: (List any two practical scenario)
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OBSERVATION AND CALCULATION – RISE AND FALL METHOD
Station BS IS FS Rise Fall RL Remarks
B.M
A
B
∑BS= ∑FS=
Check:
∑BS-∑FS =∑Rise-∑Fall= Last RL – First RL.
RESULT:
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Determination of RL of an object above the plane of collimation using inverted leveling.
AIM:To determine the RL of a point which is above the horizontal line of sight?
PROCEDURE:
1. Let B be the point whose level is to be determined.
2. Setup the instrument at ‘O’ and the instrument is levelled by temporary adjustments.
3. Direct the telescope towards the bench mark (A) and note the corresponding staff
reading
4. Hold the staff in inverted position at point B and note the corresponding staff reading.
Fig.7.4: Inverted Levelling
Station B.S F.S H.I R.L Remarks
1 BM
2 Point B
Check:
∑BS-∑FS = Last RL – First RL.
RESULTS: The RL ofB is __________ M
Practical Application: (List any two practical scenario)
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EXPERIMENT 8 - To determine the difference in elevation between using reciprocal
leveling and to determine the collimation error
AIM:To determine the difference in elevation between two points using Reciprocal Leveling
and determination of Collimation Error
APPARATUS:
a. Dumpy Level with stand
b. Leveling Staff
c. Arrow's
d. Ranging rods.
THEORY: When it is necessary to carry leveling across a river, ravine or any Obstacle
requiring a long sight distance between two points so situated that no place for level can be
found from which the length of foresight and back sight will be even approximately equal,
special method i.e., reciprocal leveling is used to obtain accuracy and to eliminate the
following. (1) Error in instrument adjustment; (2) Combined effect of earth's curvature and
refraction of the atmosphere and (3) Variation in the average refraction.
Fig.8.1: Reciprocal Levelling
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PROCEDURE:
a) Let A and B be the two points on opposite banks of the river whose difference in
elevation is to be determined,
b) Set up the instrument very near to A and with the bubble central take readings on the
staff held at A and B, say a1 and b1 respectively.
c) Transfer the instrument to B and set it up very near to B.
d) With the bubble in the central, note down the staff readings on the staff at A and B,
say a2 and b2 respectively,
e) Calculate the true difference in elevation between two points and the collimation
error as given below.
Observations:
Instrument
At Staff reading at A Staff Reading at B
A a1 = b1 =
B a2 = b2 =
Specimen Calculation:
We have
D = (b1-e)-a1 ------- (1)
D= (b2-a2) f e ------ (2)
Adding (1) and (2)
D = (1/2 ) {(b1 – a1) + (b2 – a2)}
D is the difference in Elevation
Equating (1) and (2)
e= (1/2) {(b1 - a1) - (b2 - a2)} e is the collimation error
Results:
Practical Application: (List any two practical scenario)
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EXPERIMENT 9 -To conduct profile leveling, cross sectioning and block leveling.
Plotting profile and cross sectioning in excel. Block contour on graph paper to scale
Profile Levelling
AIM: To conduct profile leveling for water supply / sewage line and to draw the longitudinal
section to determine the depth of cut and depth of filling for a given formation level.
INSTRUMENTS USED:
a. Dumpy level with tripod,
b. Prismatic compass,
c. Chain,
d. Tape,
e. Ranging rods,
f. Arrow pins,
g. Leveling staff.
THEORY: Profile leveling is the process of determining the elevations of points along a
fixed line such as center line of a railway, highway, canal, water supply and sewer. The fixed
line may be a single straight line or a series of straight lines connected by curves. It is also
known as longitudinal sectioning. By means of such sections it is possible to study the
relationship between the existing ground surface and the levels of the proposed construction
in the direction of its length. The profile is usually plotted on specially prepared profile
paper, on which the vertical scale is much larger than the horizontal, and on this profile,
various studies relating to the fixing of grades or formation lines and the estimation of
depths, volume of earthwork and estimating of costs are made.
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Fig.9.1: Profile Levelling
PROCEDURE:
1. Fix the center line alignment for the project under consideration.
2. Mark the points on this alignment at regular intervals by means of arrow pins.
3. Note down the bearings of each section of line by setting the prismatic compass at
each of the turning points.
4. Set up the Dumpy level to one side of the profile line and note down the BS reading
by holding the staff on the nearby B.M and calculates the Hl for the first station.
5. Hold the staff at each of the point marked on the profile line and note down the I.S.
6. When the readings on the staff are not very clear, note down the staff reading FS. By
holding the staff on a permanent point.
7. Shift the instrument and set it further equalizing the length of F.S. and BS and then
note down the BS
8. Repeat the procedure from step (4) onwards till the end of the profile line.
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Observation and Calculation
In
st. S
t.
Dis
tan
ce
BS
IS
FS
H.I
R.L
rem
ark
s
B.M. R.L. of
B.M.
A
Check:
∑BS-∑FS = Last RL – First RL.
RESULTS:
Practical Application: (List any two practical scenario)
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Cross Sectioning
AIM: To conduct cross sectioning to know the nature of the ground across the center line of
any alignment.
INSTRUMENTS USED:
a. Dumpy level with tripod,
b. Prismatic compass,
c. Chain,
d. Tape,
e. Ranging rods,
f. Arrow pins,
g. Leveling staff.
THEORY: it is the operation of leveling to determine the elevation of the points at right
angles on either sides of the center line of the proposed route. This is done to find out the
vertical sections of the surface of the earth on the ground. Cross section leveling helps in
computing the quantity of earthwork. The cross sections are plotted in the same manner as
longitudinal sections except that both the horizontal and vertical measurement is plotted to
the same scale.
Fig.9.2: Cross-Sectioning
PROCEDURE:
1. Fix the center line alignment for the project under consideration.
2. Mark the points on this alignment at regular intervals by means of arrow pins.
3. Note down the bearings of each section of line by setting the prismatic compass at
each of the turning points.
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4. Set up the Dumpy level to one side of the profile line and note down the BS reading
by holding the staff on the nearby B.M and calculates the Hl for the first station.
5. Hold the staff at each of the point marked on the profile line and note down the I.S.
6. Cross sections are taken at regular intervals (such as 0,5,10,15,20……) along the
alignment.
7. When the readings on the staff are not very clear, note down the staff reading FS. By
holding the staff on a permanent point.
8. Shift the instrument and set it further equalizing the length of F.S. and BS and then
note down the BS
9. Repeat the procedure from step (4) onwards till the end of the profile line.
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OBSERVATIONS AND CALCULATIONS
Inst
. S
t.
Distance
BS
IS
FS
H.I
R.L
rem
ark
s
L C R
B.M.
A 0
Cross
sectioning
at 0 meter
chainage
L1
L2
R1
R2
B 10
Cross
sectioning
at 10
meter
chainage
L1
L2
R1
R2
C 20
Cross
sectioning
at 20
meter
chainage
L1
L2
R1
R2
CHECK
Check:
∑BS-∑FS = Last RL – First RL
RESULT:
Practical Application: (List any two practical scenario)
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Block leveling, preparation of contour plan using excel. Use of planimeter/graph and
computations of Areas and volumes.
Block Levelling
AIM: To conduct Block leveling at the required place.
INSTRUMENTS REQUIRED:
a. Dumpy level with tripod stand
b. Levelling staff
c. Measuring tape
d. Chain
e. Arrows
f. Ranging rods.
THEORY:
This method is used when the area to be surveyed is small and the ground is not very
much undulated. The area to be surveyed is divided into a number of squares. The size of the
square may vary from 5-20m depending upon the nature of the contour and contour interval.
The contour lines may then be drawn by interpolation. It is not necessary that the squares
may be of the same size. Block levelling is also known as spot levelling.
PROCEDURE
Fig.9.3: Block Levelling – Perspective View
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Fig.9.4: Block Levelling - Plotting
1.The dumpy level is placed at suitable positions so that all the points on the block are
visible and after temporary adjustment the staff readings are taken.
2.The first staff reading of any set up is entered in the BS column and the last in the FS
column. The other readings are entered in the IS column.
3.Prepare a grid of blocks at regular intervals.
4.Note down the staff reading on each intersecting points of the block.
5.Draw the block diagram and the contours from the calculated RL’s.
OBSERVATIONS & CALCULATIONS
BS IS FS HI RL Distance Station Remarks
RESULT
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The block leveling has been carried out on the given profile of the ground for suitable
size of the block.
Contouring
AIM: To calculate the area and volume of the obtained contours of particular work.
THEORY: Contour is an imaginary line on the ground joining the points of equal elevation.
It is a line in which the surface of the ground is intersected by a level surface.
OBSERVATIONS & CALCULATIONS
The Area of the contours can be calculated by using digital Planimeter.
The Volume of the contours can be calculated by using Trapezoidal and Prismoidal
formula.
Prismoidal formula:
V = 𝑑
3 [(𝐴1 + 𝐴𝑛) + 4 (𝐴2 + 𝐴4 … … … 𝐴𝑛 − 1) + 2(𝐴3 + 𝐴5 … … . 𝐴𝑛 − 2)]
Trapezoidal formula:
V = d [(𝐴1+𝐴2)
2+ 𝐴2 + 𝐴3 + ⋯ … … + 𝐴𝑛 − 1]
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EXPERIMENT 10- Measurement of horizontal angle by repetition and reiteration
methods and measurement of vertical angles using theodolite
Method of Repetition
AIM: To determine the horizontal angle between two points by method of Repetition
INSTRUMENTS AND ACCESSORIES:
a. Transit Theodolite
b. Ranging Rod -02 No’s
c. Tripod stand
d. pegs-01 No
THEORY: The repetition method of measuring horizontal angles is adopted for survey
works of high accuracy. Also this method eliminates a large number of instrumental errors.
The following errors can be eliminated.
(i) Averaging both the verniers eliminates the error due to the eccentricity of the
verniers.
(ii) Averaging face left and face right observations eliminates collimination error and
trunnion axis error.
(iii) Errors of bisection are minimized taking a large number of observations.
(iv) Errors of graduations are eliminated by reading the angle on different parts of the
circle.
PROCEDURE:
Fig.10.1: Method of Repetition
With reference to the Figure, the procedure to measure angle AOB shall be as follows
1. Set the instrument on the station and make the temporary adjustment.
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2. With both the clamps released the lower plate reading is brought to nearly 0o, the
upper clamp is then tightened and the reading is made precisely 0o 0’0” by using the
upper tangent screw.
3. Release the lower clamp and swing the telescope until the left-hand station (‘A’) is
approximately sighted, tighten the lower tangent screw. The exact bisection should be
achieved through the lower tangent screw.
4. Unclamp the upper clamp. Swing the telescope in clockwise direction, until the
second station (‘B’) is sighted, tighten the upper clamp. Bisect the station exactly
with the help of the upper tangent screw. The lower plate reading will give the
horizontal angle.
5. Release the lower clamp and once again bisect the left-hand station (‘A’) exactly.
6. Unclamp the upper clamp. Swing the telescope in clockwise direction, until the
second station (‘B’) is sighted accurately. This completes two repetitions and the
lower plate reading now gives double horizontal angle.
7. The procedure (steps 5 and 6) is repeated three to six times, depending upon the
accuracy required.
8. Note the readings against vernier A& vernier B, and the mean horizontal angle is
obtained.
9. Change the face of the instrument and repeat the above procedure (steps 2 to 7).
10. The average of the two face observations gives the required horizontal angle.
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Instrument
Stn
Object
Stn
Face:LEFT Swing: RIGHT
Vernier ‘A’ Vernier ‘B’ Vernier Mean
No of
Repetition
Horizontal
Angle
o ‘ “ ‘ “ o ‘ “ o ‘ “
O
A
1 B
A
2 B
A
3 B
Instrument
Stn
Object
Stn
Face:RIGHT Swing: LEFT
Vernier ‘A’ Vernier ‘B’ Vernier Mean
No of
Repetition
Horizontal
Angle
o ‘ “ ‘ “ o ‘ “ o ‘ “
O
A
1 B
A
2 B
A
3 B
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Position
of
Vertical
Circle
Trial
No.
Horizontal
Angle
Average
Horizontal
Angle
o ‘ “
Face
Left
1
2
3
Face
Right
1
2
3
Average horizontal angle
RESULTS: The horizontal angle after 03 repetitions each on face left and face right is =
AOB = o “ ‘
Practical Application: (List any two practical scenario)
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Measurement of Horizontal Angle-Method of Reiteration
AIM: To Determine the Horizontal Angle between More than Two Points by Method of
Reiteration
INSTRUMENT AND ACCESSORIES:
a. Transit Theodolite
b. Ranging Rod-04 No’s
c. Tripod stand
d. Pegs-01
THEORY: When more than one angle is to be measured at a station, the reiteration
method of measuring horizontal angles is adopted. This method enhances the accuracy of
measurement. Also this method eliminates certain instrumental errors. The following are
the errors that can be eliminated.
(i) Errors of graduations is eliminated by reading the angle on different parts of
the circle
(ii) The closing error can be checked
PROCEDURE:
Fig.10.2: Method of Reitiration
With reference to the Figure, the procedure to measure the angles AOB, BOC, COD and
DOA shall be as follows:
1. Set the instrument on the station and make the temporary adjustments.
2. With both the clamps released the lower plate reading is brought to nearly 0o the
upper clamp is then tightened and the reading is made precisely 0o 0’0” by using the
upper tangent screw.
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3. Release the lower clamp and swing the telescope until the first station (‘A’) is
approximately sighted, tighten the lower tangent screw. The exact bisection should be
achieved through the lower tangent screw.
4. Unclamp the upper clamp, Swing the telescope in clockwise direction, until the
second station (‘B’) is sighted, tighten the upper clamp. Bisect the station exactly with
the help of the upper tangent screw.
5. Note down the vernier readings, the difference in the vernier readings will give the
angle AOB.
6. Release the upper clamp and bisect the next station (‘C’) precisely using the upper
clamp and tangent screw.
7. Note down the vernier readings, the difference in the vernier readings will give the
angle BOC.
8. Repeat the procedure (step 6 and 7) so as to bisect station ‘D’ and obtain angle
COD.
9. From the last station (‘D’) close the work b sighting the first station (‘A’).
10. Note the vernier reading and check whether it is within permissible limits and
obtain the corrected angles.
11. Change the face of the instrument and repeat the above procedure (steps 2 to 7).
12. The average of the two face observations gives the required horizontal angle.
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Insrument
Stn
Object
Stn
Face : Left
Swing : Right
Ver ‘A’ Ver ‘B’ Vernier Mean
Horizontal
Angle o ‘ “ ‘ “ o ‘ “ o ‘ “
O
A AOB=
B BOC=
C COD=
D DOA=
A
Insrument
Stn
Object
Stn
Face : Right
Swing : Left
Ver ‘A’ Ver ‘B’ Vernier Mean
Horizontal
Angle o ‘ “ ‘ “ o ‘ “ o ‘ “
O
A AOB=
B BOC=
C COD=
D DOA=
A
RESULT: The average angles obtained by the method of Reiteration are as follows:
AOB= COD=
BOC= DOA=
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Measurement of vertical angles using theodolite.
AIM: To Measure The Vertical Angle Of The Object ‘A’ Shown With Respect To The
Station O.
APPARATUS:
a. Theodolite
b. ranging rods
c. Tape
THEORY: A Vertical is the angle which the inclined line of right to an object makes with
the horizontal. The vertical angle is the angle of elevation when the line of sight is inclined
upwards from the horizontal line. It is the angle of depression when the line of sight is
inclined downward from the horizontal line.
PROCEDURE:
Fig.10.3: Vertical Angle Measurement
1) Set up the theodolite over the station O and level it accurately with reference to the
altitude bubble.
2) Set the zero of the vernier ‘C’ exactly to the zero of the vertical circle by means of
the vertical circle clamp and tangent screw.
3) Bring the bubble of the altitude level to center of its run by means of clip screw the
line of collimation is the made horizontal which vernier reads zero.
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4) Loosen the vertical circle clamp and direct the telescope towards the object A,
clamp the vertical circle clamp. Bisect A exactly by turning the tangent screw.
5) Read both the verniers C&D the mean of the two readings given the value of the
required angle.
6) Change the face of the instrument and repeat the same procedure. The mean of the
two vernier readings given the second value of the required angles.
7) The average of the two values thus obtained given the value of the required vertical
angle.
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OBSERVATIONS
1. Measurement of Vertical Angles
Instrument
Stn
Point
Sighted
Face : Left Swing :
Right
Ver ‘C’ Ver ‘D’ Vernier Mean Vertical Angle
o ‘ “ ‘ “ o ‘ “ o ‘ “
O A
Insrument
Stn
Point
Sighted
Face :Right Swing
: Left
Ver ‘C’ Ver ‘D’ Vernier Mean Vertical Angle
o ‘ “ ‘ “ o ‘ “ o ‘ “
O A
RESULT:
Vertical angle = o
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EXPERIMENT 11-Determination of horizontal distance and vertical height to a
base inaccessible object using theodolite by single plane and double plane method.
Elevation of an Inaccessible Object by Single Plane Method.
AIM: To determine the reduced level of an elevated object whose base is inaccessible
from the instrument station.
INSTRUMENTS AND ACCESSORIES:
a) Transit Theodolite with accessories
b) Levelling Staff- 01 No
c) Tripod stand
d) Pegs 02 No
e) Metallic tape
THEORY: A Theodolite can be used for the determination of the heights and distances of
objects, which are inaccessible. For example, the top of the Hill or an object bounded by
water. In such situations observations have to be made from two established stations. The
two instrument stations and the object may or may not be in the same vertical plane. In
this case the two instrument stations are so chosen that they are in the same vertical plane
as that of the object. This method is called as single plane method. With an adequate
number of angular and linear measurements, the required quantities can be computed from
the trigonometry of the figure.
With reference to the figure we have,
h1=D tan α1, h2= (b+D) tan α2
From the geometry of the figure, on simplification,
D= [btan α2 ±S] / [tan α1 - tan α2]
In the above expression ‘+’ sign is used when the instrument axis at the further station is
higher than that at the station near to the object and ‘-‘ sign is used for vice versa.
RL of top of the object = RL of BM + S1+D tan α1OR
RL of top of the object=RL of BM+S2+(b+D) tan α2
PROCEDURE:
1. Set the Theodolite at a convenient position from the object such that the vertical
angles shall be between 30o to 60o.
2. Level the instrument and eliminate the parallax.
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3. Transfer the instrument center to the ground with a plumb bob as
station ‘A’.
4. Obtain the vertical angle above the horizontal axis at stn. ‘A’ to the top of the
object by accurately sighting the top using the vertical clamp and tangent screw.
5. Repeat step No.4 by changing the face and obtain the average vertical angle at ‘A’
6. Keeping the line of collimation horizontal take staff reading on the B.M.
7. Transit the Theodolite so as to locate station ‘B’ in the same vertical plane.
8. Measure a suitable distance ‘b’ from station ‘A’ to locate station ‘B’.
9. Shift the instrument to station ‘B’ and carry out centering and leveling.
10. Obtain the vertical angle above the horizontal axis at stn. ‘B’ to the top of the
object by accurately sighting the top using the vertical clamp and tangent screw.
11. Repeat step No.10 by changing the face and obtain the average vertical angle at
‘B’.
12. Keeping the line of collimation horizontal take staff reading on the B.M.
13. Calculate the height and RL of the object using the trigonometric formulations.
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Distance and Elevation of an inaccessible object by Single Plane Method.
FIGURE
Fig.11.1: Single Plane Method
OBSERVATIONS
1. Measurement of Vertical Angles
Insrument
Stn
Point
Sighted
Face : Left Swing :
Right
Ver ‘C’ Ver ‘D’ Vernier Mean Vertical Angle
o ‘ “ ‘ “ o ‘ “ o ‘ “
A TOP
B TOP
h1=Dtanα1
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Insrument
Stn
Point
Sighted
Face : Right Swing :
Left
Ver ‘C’ Ver ‘D’ Vernier Mean Vertical Angle
o ‘ “ ‘ “ o ‘ “ o ‘ “
A TOP
B TOP
The average vertical angles are
α1 = α2 =
2.Staff reading on Bench Mark
From station ‘A’=S1=
Form station ‘B’=S2=
3. Horizontal distance between stn. ‘A’ and stn.’B’= b = -------
CALCULATIONS AND RESULTS:
Distance from station ‘A’ to the object, D= [ btan α2 ±S] / [tan α1 - tan α2] = -----M
RL of top of the object=RL of BM+S1+ D tan α1 = ------M
CHECK:
RL of top of the object= RL of BM+S2+ (b+D) tan α2 =-----------M
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Distance and Elevation of an Inaccessible Object by Double Plane Method.
AIM: To determine the distance reduced level of an elevated object whose base is
inaccessible from the instrument station.
INSTURMENTS AND ACCESSORIES:
(i) Transit Theodolite with accessories (iv) leveling /staff-01 No
(ii) Tripod stand (v) Pegs-02
(iii) Metallic Tape
THEORY: A Theodolite can be used for the determination of the heights and distances
of objects, which are inaccessible. For example the top of a hill or an object bounded by
water. In such situations observations have to be made from two established stations. The
two instrument stations and the object may or may not be in the same vertical plane. In
this case the two instrument stations are so chosen that they are in the two different
vertical planes as that of the object. This method is called a double plane method. With an
adequate number of angular and linear measurement, the required quantities can be
computed from the trigonometry of the figure.
With reference to the figure we have,
h1=D1 tan α1 h2=D2 tan α2
From the geometry of the figure, on simplification,
D1=[bSinƟ2] / [Sin(1 + 2] And D2 =[bSinƟ1] / [Sin(1 + 2]
RL of top of the object=RL of BM +S1+h1
RL of top of the object=RL of BM+S2+h2
PROCEDURE:
1. Set the Theodolite at a convenient position from the object such that the vertical
angle shall be between 30o to 60o
2. Level the instrument and eliminate the parallax.
3. Transfer the instrument center to the ground with a plumb bob as station ‘P’.
4. Obtain the vertical angle above the horizontal axis at station. ‘P’ to the top of the
object by accurately sighting the top using the vertical clamp and tangent screw.
5. Repeat step No.4 by changing the face and obtain the average vertical angle at
‘P’.
6. Keeping the line of collimation horizontal take staff reading on the B.M.
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7. Locate station ‘R’ at a suitable distance from ‘P’ such that the angles of the
horizontal triangle formed by station ‘P’, station ‘R’ and the object shall be
between 30o to 60o.
8. Measure the distance ‘b’ from station ‘P’ to station ‘R’.
9. Shift the instrument to station ‘R’ and carry out centering and leveling.
10. Obtain the vertical angle above the horizontal axis at station ‘R’ to the top of the
object by accurately sighting the top using the vertical clamp and tangent screw.
11. Repeat step No. 10 by changing the face and obtain the average vertical angle at
‘R’.
12. Keeping the line of collimation horizontal take staff reading on the B.M.
13. Calculate the height and RL of the object using the trigonometric formulations.
Distance and Elevation of an inaccessible object by Double plane Method
FIGURE:
Fig.11.2: Double Plane Method
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OBSERVATIONS AND CALCULATIONS
1. Measurement of Vertical Angles
Insrument
Stn
Point
Sighted
Ver ‘C’ Ver ‘D’ Vernier Mean Vertical Angle-
α1
o ‘ “ ‘ “ o ‘ “ o ‘ “
PLeft TOP
PRight TOP
Insrument
Stn
Point
Sighted
Ver ‘C’ Ver ‘D’ Vernier Mean Vertical Angle-
α2
o ‘ “ ‘ “ o ‘ “ o ‘ “
RLeft TOP
RRight TOP
The average vertical angles are: α1= α2=
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2.Measurement of Horizontal Angles
Insrument
Stn Point Sighted
Ver ‘A’ Ver ‘B’ Vernier Mean Horizontal
Angle
Average
Horizontal
Angle-θ1
o ‘ “ ‘ “ o ‘ “ o ‘ “ o ‘ “
PLeft Elevated Object
R
PRight Elevated Object
R
Insrument
Stn Point Sighted
Ver ‘A’ Ver ‘B’ Vernier Mean Horizontal
Angle
Average
Horizontal
Angle-θ2
o ‘ “ ‘ “ o ‘ “ o ‘ “ o ‘ “
RLeft Elevated Object
P
RRight Elevated Object
P
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The average horizontal angles are: Ɵ1= Ɵ2
3. Staff reading on Bench Mark: From station ‘P’ = S1= and from station
‘R’= S1=
4. Horizontal distance between stn. ‘P’ and stn. ‘R’=d=
CALCULATIONS AND RESULTS:
1. Distance from station ‘P’ to the object= D1 = [bSinƟ2] / [Sin (Ɵ1 + Ɵ2]
2. Distance from station ‘R’ to the object= D2 = [bSinƟ1] / [Sin (Ɵ1 + Ɵ2]
3. RL of top of the object=RL of BM+S1+h 1=-----------m
Check
RL of top of the object=RL of BM+S2+h2=--------------m
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EXPERIMENT 12- To determine distance and elevation using tacheometric surveying
with horizontal and inclines line of sight.
AIM: - to determine distance and elevation using tacheometric surveying with horizontal
and inclines line of sight.
INSTRUMENTS AND ACCESSORIES:
a) Tacheometer (Transit Theodolite / Dumpy level)
b) Tripod stand
c) Levelling Staff-01No
d) Metallic Tape
e) Pegs-02 Nos
f) ranging rods-03 No’s
THEORY: Tacheometry is a branch of surveying in which distances and elevations are
determined from instrumental observations only. The basic principle of stadia method of
tacheometry is that if the length of the base and the apex angle of an isosceles or right
angled triangle are known, the perpendicular distance from the apex can be calculated.
The distance formula for horizontal line of sight is
D = Ks+ C
The tacheometer is so constructed that normally K=100 and by fixing a anallactic lens the
additive Constant is made zero.
PROCEDURE:
1. Set the instrument at Q and level it. With the help of upper clamp and upper tangent
provided at the vertical circle set vernier C to 0º00´00´´. Which keeps the telescope
horizontal.
2. Direct the telescope towards the point P where distance and elevation of the point is to
be determined. Bisect point P accurately by upper clamp and tangent screws.
3. After exact bisection measure central stadia reading, staff intercept and Staff reading
on BM.
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OBSERVATIONS & CALCULATIONS
Staff Intercept = S = ……….M
Staff Reading on Benchmark = ……………M
Central Cross Hair reading = ………………M
Fig.12.1: Tacheometric Surveying – Horizontal Line of Sight
FORMULA
1)Distance, D=KS+C
2)Elevation = RL of Bench mark +Staff Reading on BM-Central Stadia Reading.
RESULT:
1) Distance=…………….…..M
2) Elevation = ………………M
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2) AIM :To determine distance and Elevation using Tachometric surveying with
Inclined line of sight
INSTRUMENTS REQUIRED
Tachometer, Leveling Staff, Chain or tape.
DIAGRAM
Fig.12.2: Tacheometric Surveying – Inclined Line of Sight
PROCEDURE
1. Set up the theodolite over the station O and level it accurately with reference to the
altitude bubble from where the distance and elevation are to be measured.
2. Unclamp the vertical circle clamp and direct the telescope towards the Staff placed at
elevated object at any inclined angle.
3. Read both the verniers C and D. The mean of the two readings gives the value of
required angle.
4. After measuring the vertical angle measure central stadia reading, staff intercept and
Staff reading on BM in order to calculate the distance and measurement.
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OBSERVATIONS AND CALCULATIONS
Staff Intercept = S = ……….M
Staff Reading on Benchmark = ……………M
Central Cross Hair reading = ………………M
Angle of elevation = o ’ ”
FORMULA
1)Distance, D=KSCos2+C Cos
2)Elevation = RL of Bench mark +Staff Reading on BM+V-h.
RESULT:
1) Distance=…………….…..M
2) Elevation = ………………M
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EXPERIMENT 13-Closed traverse surveying using theodolite and applying corrections
for error of closure by transit rule.
AIM: To measure the bearings of the sides of the closed traverse and adjustment of the
closing error by Transit rule.
INSTRUMENTS REQUIRED:
a. Theodolite with stand
b. Chain/tape
c. Ranging rods
d. Arrows.
THEORY:
A ‘traverse’ is a frame formed by a series of connected straight lines, none of
which is connected at each of its ends to lines more than one. The points defining the ends
of the traverse line are called traverse stations or traverse points. When the lines form a
circuit which ends at the starting point is known as a closed traverse. If the circuit ends
elsewhere, it is said to be an open traverse. Closed traverse is suitable for locating
boundaries of lakes, forests etc. Open traverse is suitable for surveying along long narrow
strip of land required for a road or canal or pipeline or the coast line.
Closing error or error of closure is the actual distance by which the traverse fails
to close. Transit method may be employed to balance the traverse when the angular
measurements are more precise than the linear measurements. In this method the total
error in latitude and departure is distributed in proportion to the latitude and departure of
the traverse lines.
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Fig.13.1: Closing Error – Transit Method
FORMULAE
Transit method:
CL= ∑𝑳𝑿𝑳
𝑳𝑻
CD= ∑𝑫𝑿𝑫
𝑫𝑻
Where CL= Correction to latitude of any side
CD= Correction to departure of any side
𝑙= Length of that side
∑ 𝐿= Total error in latitude
∑ 𝐷= Total error in departure
L= Latitude of that side
LT= Arithmetic sum of latitudes (Ignoring the signs)
D= Departure of that side
DT= Arithmetic sum of departures (Ignoring the signs).
PROCEDURE:
1. Let A, B, C, D, E are the traverse stations.
2. Set the Theodolite at station ‘A’ keeping theodolite reading at 0, and sighting the
line AB. Measure the distance AB.
3. Now shift the instrument to the station ‘B’, Measure the horizontal angle BC.
4. Similarly the length and angles of each line of the traverse is to be measured.
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OBSERVATIONS & CALCULATIONS
Transit Method
SL.
NO.
Line Length
(𝑙)in m
Angle Latitude
L=𝑙𝐶𝑜𝑠𝜃
Departure
D=𝑙𝑆𝑖𝑛𝜃
Corrections Corrected
Lat
itude
Dep
artu
re
Lat
itude
Dep
artu
re
1
2
3
4
5
6
∑ 𝐿= ……………∑ 𝐷= ……………
RESULT:
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EXPERIMENT 14 -Demonstration of minor instruments
Hand Level
Hand level is a small compact leveling instrument which can be held in hand and leveling
work carried on. It is used for
(i) Reconnaissance and preliminary survey
(ii) Locating contours, and
(iii) Taking short cross-section
Fig.14.1: Hand Level
It consists of a rectangular tube 100 mm to 150 mm long. There is a small opening at
the top of the tube and a level tube is fitted exactly above this. The level tube is
transparent both at top and below.
Below this, in half the width of tube a mirror is fixed at 450. The other half width is
clear. At one end of the tube there is eye peep hole and at other end there is objective.
When the staff is sighted through the eye peep hole in half the portion staff is seen directly
while in other half, level bubble is seen. When in perfect adjustment, if hand level is held
horizontal, the middle of bubble and cross hair coincide and the reading is the correct staff
reading in the horizontal sight. Hence, it can be used as a leveling instrument. It is usually
held in hand at eye levels and observations are made. It may be suspended from a raging
rod for greater stability.
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Box Sextant
The box sextant is small pocket instrument used for measuring used for measuring
horizontal and vernier angles, measuring chain angles and locating inaccessible points. By
setting the vernier 900 it may be used as an optical square. Fig shows a box sextant.
Fig.14.2: Box Sextant
A box sextant consists of the following parts:
(1) A circular box about 8cm in diameter and 4cm high.
(2) A fixed horizon glass, silvered at lower half and plain at upper half.
(3) A movable index glass fully silvered.
(4) An index arm pivoted at the index glass and carrying a vernier at the other end.
(5) An adjustable magnifying glass, to read the angle
(6) A milled-headed screw to rotate the index glass and the index arm.
(7) An eye ole or peep hole or a telescope for long distance sighting.
(8) A pair of colored glasses for use in bright sun.
(9) A slot in the side of the box for the object to be sighted.
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Clinometer
Fig.14.3: Indian Pattern Clinometer (Tangent Clinometer)
Indian pattern clinometer is used for determining difference in elevation between
points and is specially adopted to plane tabling. The clinometer is placed on the plane
table, which is leveled by estimation. The clinometer is composed of the following:
1. A base plate carrying a small bubble tube and a leveling screw. Thus, the
clinometer can be accurately leveled.
2. The eye vane carrying a peep hole. The eye vane is hinged at its lower end to the
base plate.
3. The object vane having graduations in degrees at one side and tangent of the angles
to the other side of the central opening.
The object vane is also hinged at its lower end to the base plate. A slide provided with
a small window and horizontal wire in its middle, can b moved up and down the object
vane by a rack and pinion fitted with a milled head. The line of joining the peephole and
the horizontal wire of the slide defines the line of sight. When the instrument is not in use,
the vanes fold down over the base.
Use of Indian pattern clinometer with plane table
1. Set the plane table over the station and keep the Indian pattern clinometer on it.
2. Level the clinometer with the help of leveling screw.
3. Looking through the peephole, move the slide of the object vane till it bisects the
signal at the other point to be sighted. It is preferable to use a signal of the same
height as that of the peephole above the level of the plane table station.
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4. Note the reading, i.e. tangent of the angle, against the wire. Thus, the difference in
elevation between the eye and the object distance X tangent of vertical angle d tan
a.
The distance d between the plane table station and the object can be found from the
plan. The reduced level of the object canthus be calculated if the reduced level of the plane
table station is known.
Ceylon Ghat Tracer
This instrument illustrated in fig is used for setting out a grade contour, i.e. locating points
on a given gradient in the preliminary survey of a hill road, and also for measuring the
angles of slope.It consist of
1. a hollow brass sighting tube suspended from a bracket and having a very small
hole (eye hole) at one extremity to which the eye is applied, and a larger opening
with cross-wires at the other the tube pivots round the point P and is held
suspended from an upright staff,
2. A horizontal racked bar the bar is parallel and rigidly and attached to the tube at a
distance of about 2.5 cms from it
3. A weight the upper part of which forms the reading index the weight can be moved
along the rack by means of a million-head screw actuating a pinion on the rack.
The line of sight is defined by the line joining the centre of the eye hole to the intersection
of the cross-wires. The sighting tube and along with it the line of sight can be set to any
desired gradient by moving the weight along the rack to the required reading on the scale.
Fig.14.4: Cylon Ghat Tracer
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Procedure: - Suppose it is required to lay out a gradient of 1 in 30 along a hill slope.
1. Hold the instrument at the given station suspending it from the pin inserted in the
upright staff.
2. Move the weight along the rack by means of the milled-head screw until the index
reads 30 on the scale.
3. Send an assistant with a sight vane (a T-shaped staff on which is marked the height of
the axis of the sighting tube above the foot of the suspending staff) to a convenient
distance, say 50 m or more along the hill slope.
4. Look through the sighting tube and direct the assistant to move up or down hill until
the cross-wires bisect the centre of the sight vane.The foot of the sight vane is then the
required point and the line from the instrument station to this line is parallel to the line
of sight is on a gradient of 1 in 30.As peg is driven at the point so obtained which
serves as the instrument station for locating the next point.
5. Proceed to the point so established and repeat the operation to locate the next point.
To measure a slope,
1.Hold the instrument at one end of the slope and a sight vane at the other.
2.Move the weight along the rack by turning the middle head screw until the centre of the
sight vane is bisected by the cross-wires.
3.Note the reading at the index edge of the weight, which gives the amount of slope
observed.
Planimeter
Fig.14.5: Planimeter
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A Planimeter is an instrument, which measures the area of plan of any shape very
accurately. There are two types of planimeters: (1) Amsler polar Planimeter, and (2) Roller
Planimeter.
The polar Planimeter is most commonly used and is therefore discussed here. It
consists of two arms hinged at a point known as the pivot point. One of the two arms
carries an anchor at its end, and is known as the anchor arm. The length of anchor arm is
generally fixed, but in some of the planimeters, a variable length of anchor arm is also
provided. The other aim carries the tracing point at its end, and is known as the tracing
arm. 1 ho length of the tracing arm can be varied by the means of a fixed screw and a
corresponding slow motion screw. The tracing point is moved along the boundary of the
plan the area of which is to be determined. The normal displacement of the tracing arm is
measured by the means of a wheelhouse axis is kept parallel to the tracing arm. The wheel
may either be placed between the hinge and the tracing point or is placed beyond the pivot
point away from the tracing point. The wheel carries a concentric drum, which is divided
into 100 divisions small vernier attached near the drum, reads one-tenth of the drum
division. The complete revolutions of the wheel are read on the disc actuated by a suitable
gearing to the wheel. Thus, each is reading is of four digits-the units being read on the
disc, the tenths and hundreds on the drum, and the thousands on the venire. In addition to
this, a fixed index near the disc can be utilized to know the number of the times the zero of
the disc has crossed the index.
It is clear that the planimeter rests on three points-the wheel, the anchor point and
the tracing point. Out of these three, the anchor point remains fixed in position while the
wheel partly rolls and partly slides as the tracing point is moved along the boundary. Since
the plane of the wheel is perpendicular to the plane of the centerline of the tracing arm, the
wheel measures only the 'normal displacement- when it actually rolls.
To find the area of the plan, the anchor point is either placed outside the area (if the
area is small) or it is placed inside the area (if the area is large). A point is then marked on
the boundary of area and the tracing point is kept exactly over it. The initial reading of the
wheel is then taken. The tracing point is now moved clockwise along the boundary till it
comes to the starting point. The final reading of the drum is taken. The area of the Figure
is then calculated from the following formula:
AREA () = m (FR – IR (+or-) 10 N + C)
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Where FR = Final reading.
IR = Initial reading
N = The number of times the zero mark of the dial passes the fixed index Mark. Use +
sign if the zero mark of the dial passes the index mark in a Clockwise direction and - sign
when it passes in anticlockwise direction.
M = A multiplying constant, also sometimes known as the planimeter constant. It is equal
to the area per revolution of the roller.
C = constant of the instrument which when multiplied by M, gives the area of zero circle.
The constant C is to be added only when the anchor point is inside the area.
It is to be noted that, the tracing point is to be moved in the clockwise direction only.
Proper sign must be given to N. The proof of the above formula is given below.
Pentagraph
Fig.14.5: Pentagraph
A Pentagraph is an instrument used for reproducing, enlarging or reducing the
maps. It is based on the principle of similar triangles. It consists of two long bars AB and
AD hinged together at A and supported on casters or rollers at B and D. Two short arms
EF and GF are hinged together at F and are connected to AD and AB at E and G
respectively. Thus ABGF is a parallelogram of equal sides for all positions of the
instrument. The long bar AD carries a tubular frame which can be slided along it. The
sliding frame carries an index and a heavy weight Q which forms the vertical axis of the
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instrument; the whole instrument moves about the point Q. The bar EF carries a pencil
point P attached to a carrier which can also be set to a desired reading on the bar EF. The
longer arm AB carries tracing point at the end B. For any setting of the instrument, the
point B, P and Q are in straight line. The original map is kept at B and is traced.
Correspondingly, the pencil point P also moves, but the point Q remains fixed in position.
Thus, if B, is moved straight by an amount BB', the point P moves to P', the ratio between
BB' and PP' being equal to the ratio of reduction. For any position of the tracing point, the
points B', P' and Q are always in a straight line.
If it is desired to enlarge the nap, the pencil point is kept at B, the tracing point at P
and the map under the point P. The moving frames at Q and P are set to the same reading
equal to the ratio of enlargement. The pencil can be raised off the paper, by means of cord
passing from the pencil round the instrument to the tracing point, if so required.
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Additional Exercise
1. Preparation of Google mapping for sampling points
2. Conducting differential levelling using total station.
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Viva-Voce
Linear Measurements
1. What is the fundamental difference between surveying and leveling?
2. What is the fundamental difference between plane surveying and geodetic surveying?
3. What do you mean by the terms ‘topographical map’ and ‘cadastral map’?
4. What is the main principle of surveying?
5. How is a chain folded and unfolded?
6. In a chaining operation, who is the leader and who the follower?
7. While chaining a line, you have to measure through a steep sloping ground. What
method should you apply?
8. Two stations are not intervisible due to intervening high ground. How will you range
the line?
9. What do you mean by normal tension?
10. What do you mean by RF?
11. What is difference between plain scale and diagonal scale?
12. What is hypotenusal allowance?
13. How many ranging rods are required to range a line?
14. What is the length of one link in a 20 m chain?
Chain Surveying
1. What is the principle of chain surveying?
2. What do you mean by triangulation?
3. Why is the triangle preferred to the quadrilateral?
4. What is the disadvantage of using ill-conditioned triangles?
5. What is reconnaissance survey?
6. What is an index sketch?
7. What is ‘base line of survey’?
8. How is the north line of the chain survey map fixed?
9. Suppose you are asked to conduct a chain survey in a crowded town. What would you
say?
10. What should be the maximum length of offset?
11. How is a station marked on the ground?
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12. What is the need of a reference sketch?
13. How will you set up a perpendicular with the help of only a chain and a tape?
14. Who are the ‘leader’ and ‘follower’ when a line is being chained?
15. Why does the field book open lengthwise?
16. Why is the scale always drawn in the map?
17. What is it necessary to provide tallies in a chain?
18. What do you mean by the term ‘ideal triangle’?
Compass Traversing
1. What is the principle of compass surveying?
2. What is the difference between triangulation and traversing?
3. What does the term ‘chain angle’ mean?
4. What is a 12cm compass?
5. What is the fundamental difference between the prismatic compass and the surveyor’s
compass?
6. How would you detect the presence of local attraction in an area?
7. The FB of a line is 96o30’ and 276o0’. How will you adjust the bearings?
8. What is local attraction?
9. What is declination?
10. What are isogonic and agonic lines?
11. What do you mean by azimuth?
12. What FB of a line is 145030’ what is its BB?
13. The FB of a line is S 45030’ w? What is its BB?
14. What are the precautions to be taken while shifting a prismatic compass from one
station to another?
15. A compass was properly balanced at the equator. What will be the effect on the needle
if it is taken to the northern hemisphere?
16. What is the angular check of a closed traverse?
17. How would you check the accuracy of open traverse?
Levelling
1. What is a datum surface?
2. What does the term GTS mean?
3. What are bench-marks?
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4. What is the datum adopted for GTS bench-marks?
5. What are the types of BM that you know of?
6. For any engineering work, how will you get the RL of the starting point?
7. What is the difference between a level surface and a horizontal surface?
8. What is the difference between the line of collimation and axis of the telescope?
9. What is the relation between the line of collimation and the axis of a telescope?
10. In a particular set up of the level, suppose four readings are taken. How should they be
entered in the level book?
11. What is a change point?
12. The staff readings on A and B are 1.735 and 0.965 respectively. Which point is
higher?
13. What is the procedure of leveling by foot screws?
14. How is the level centered?
15. Suppose a level is given to you whose line of collimation is not in adjustment, what is
the procedure that you would follow in order to work with this instrument?
16. How will you continue leveling across a river?
17. How will you continue leveling across a lake or pond?
18. What are the arithmetical cheeks for the HI method and the rise and fall method?
19. What is fly leveling?
20. What is check leveling?
21. What is temporary bench mark?
22. Why is datum assumed for plotting a leveling operation?
23. What is difference between temporary and permanent adjustment?
24. What would you mean by positive RL and negative RL?
Theodolite Traversing
1. What is a transit theodolite?
2. What is a 12 cm theodolite?
3. What are the functions of a theodolite?
4. Describe the location and function of the plate bubble and the altitude bubble?
5. What is the function of the shifting head?
6. State the procedure involved in bringing the bubble to the center?
7. What are the functions of the clamp screw, tangent screw and clip screw?
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8. What do the terms ‘face left’ and ‘face right’ mean?
9. What do the terms ‘telescope normal ‘and ‘telescope inverted’ mean?
10. What is an azimuth?
11. What is a trunnion axis?
12. What is transiting?
13. What does ‘swinging the telescope’ mean?
14. What is the least count of a theodolite?
15. How can a theodolite be used as level?
16. What is a deflection angle?
17. Why are face left and face right observations taken?
18. Why are two Vernier readings taken?
19. What do you know about repeating theodolites and direction theodolites?
20. Name some modern theodolites.
21. What do the terms ‘consecutive coordinates’ and ‘independent coordinates’ mean?
22. What are latitude and departure?
23. What are the sign conventions of latitudes and departures?
24. What is Gale’s table? What is the characteristic of this table?
Tacheometric Survey
1. What is tacheometry?
2. What is the difference between a theodolite and tacheometer?
3. Why is an anallatic lens provided in a tacheometer?
4. What is the difference between a fixed hair tacheometer and a subtense theodolite?
5. What are the multiplying constant and additive constant of a tacheometer?
6. What is subtense bar?
7. What is tangential tacheometry?
8. What is the principle of tacheometry?
9. What does ‘reduction of readings’ mean?
10. What is the purpose of a direct reading tacheometer?