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SURVEYING FIELD WORK-I MANUAL
(AS PER C.S.V.T.U SYLLABUS)
SURVEYING FIELD WORK-I MANUAL/MADHAVA.N/CIET,RAIPUR
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COLUMBIA INSTITUTE OF ENGINEERING AND TECHNOLOGY
NEAR VIDHAN SABHA, RAIPUR(C.G)
CONTENTS
S.NO
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2
3
4
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7
8
9
10
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14
15
NAME OF THE EXPERIMENT
PACE DETERMINATION
CHAIN SURVEYING
COMPASS SURVEYING
FLY LEVELLING
SENSITIVITY OF BUBBLE TUBE
CONTOURING AND ITS PLOTTING.
STUDY OF THEODOLITE
REPETITION METHOD.
REITERATION METHOD.
HEIGHT OF AN OBJECT
STUDY OF PLANE TABLE
RADIATION METHOD
INTERSECTION METHOD.
TWO POINT PROBLEM
THE THREE POINT PROBLEM
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Instructions to students
FIELD NOTES
A record of each field assignment shall be kept in your field book. Your field book shall be
kept neat and orderly. It will be collected for the evaluation of your performance in field
work.
FIELD GROUPS
Each student will be assigned to a 4 or 5 people group. A group head will be appointed who
will be taking care of the lab equipment.
EQUIPMENT REGISTER
The group head appointed will be responsible for signing in the register for issue and return
of the equipment for the lab session. No damage of equipment should be ensured.
ATTENDANCE
Attendance is important for better learning and scoring of good marks.
PROJECT WORK
Each student as a group shall perform some project work in surveying for any civil
engineering project and gain some practical experience. A report of your work should be
submitted at the end of the semester.
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EXP NO.1: PACE DETERMINATION
Aim: To estimate your own pace
Equipment: Steel tape, chaining pins
Theory:
 Pacing is a reasonably easy and quick method of measuring distance in the
field. Pacing is a method used to measure a distance and is often used with a
sighting or hand compass.
 Most commonly, pacing is split up into segments, such as chains, which are
set measures of distance.
 By determining your own pace, distance can easily be estimated.
 Pacing saves time but is not as accurate as using a tape measure and can be
affected by terrain such as steep slopes, rocky areas, streams, and thick brush.
 Good pacing can only be accomplished by practice. Knowing the distance of
your pace will help to ensure the accuracy and precision of pacing distances.
Procedure:
1. Place chaining pins in the ground at 0 m, 30 m, 60 m, 90 m stations.
2. Use a plumb bob to ensure that all pins are in a straight line.
3. Use your normal walk to pace off each distance (i.e.: 0 m to 30 m, 0 m to 60 m and 0
m to 90 m) a total of 3 times each.
4. Record the number of paces for each trial in your field book.
5. Calculate the average number of paces for each distance.
6. Calculate the average length of your pace i.e., Pace Factor
Pace factor, PF = Distance/average no. of paces
PF unit: meter per pace or feet per pace
Observations and calculations:
Trial no.
Distance 1(
1
2
3
Average no. of
paces
Pace factor
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)
Distance 2(
)
Distance 3(
)
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EXP NO.2: CHAIN SURVEYING
Aim:
To Measure distance by a surveying chain.
Equipment: Chain, Arrows, Tapes, Ranging Rods.
Theory:
 By various methods of determining distance, the most accurate and common method
is the method of measuring distance with a chain or tape which is called Chaining.
 For work of ordinary precision a chain is used. But where great accuracy is required a
steel tape is invariably used.
 The survey party consists of
o A leader (the surveyor at the forward end of the chain)
o A follower (the surveyor at the rare end of the chain and an assistant to
establish intermediate points).
 The precision of chaining for ordinary work, ranges from 1/1000 to 1/30,000 and
precise measurement such as baseline may be of the order of 1000000.
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Procedure:
Unfolding the chain:
To unfold the chain, the chainmen keeps both the handles in the left hand and throws
the rest of the portion of the chain in the forward direction with his right hand. The other
chainman assists in removing the knots etc. and in making the chain straight.
Ranging and chaining:
1. The follower holds the zero end of the chain at the terminal point while the leader
proceeds forward with the other end in one hand and a set of 10 arrows and a ranging
rod in other hand.
2. When he is approximately one chain length away the follower directs him to fix the
ranging rod in line with the terminal poles.
3. When the point is ranged, the leader makes a mark on the ground, holds the handle
with both the hands and pulls the chain so that it becomes straight between the
terminal point and the point fixed.
4. The leader then puts an arrow at the end of the chain, swings the chain slightly out of
the line and proceeds further with the handle in one hand and the rest of the arrows
and ranging rod in the other hand.
5. The follower also takes the end handle in one hand and a ranging rod in the other
hand, follows the leader till the leader approximately travelled one chain length.
6. Steps 2, 3,4,5 repeats
7. The follower takes the first arrow and the ranging rod in one hand and the handle in
the other and follows the leader.
8. At the end of ten chains, the leader calls for the ‘arrows’. The follower takes out the
tenth arrow from the ground, puts a ranging rod there and hands over ten arrows to the
leader.
9. The transfer of ten arrows is recorded by the surveyor.
10. To measure the fractional length at the end of a line, the leader drags the chain beyond
the end station, stretches it straight and tight and reads the links.
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OBSERVATIONS AND CALCULATIONS:
a. No. of arrows recorded
b. No. of links counted at the end
c. length of chain
d. length of each link
e. total distance measured (a x c + b x d)
RESULT:
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EXP.NO.3: COMPASS SURVEYING
Aim:
To measure bearings of sides of traverse with prismatic compass and
computation of correct included angle.
Equipment: Prismatic compass, ranging rod, chain, tape, peg, Tripod stand
Theory:
 Prismatic compass is used to measure bearing of survey lines.
 The least count of prismatic compass is 30 min.
 It consists of circular box of 10cm-12 cm dia. of non magnetic material.
 A sharp pivot made up of hard steel is fixed at the centre of box
 It is graduated in clockwise direction from 0 deg to 360 deg.
 Zero Is written at south end and 180 at north end and 270 at the east. Diametrically
opposite are fixed to the box.
 The sighting vane consists of a hinged metal frame in the centre of which a vertical
Horse hair or fine silk thread is stretched a vertical hair.
 lifting pin presses against the needle of the pivot and holds it against the glass lid.
Thus preventing the wear of the pivot point to damp the oscillations of the needle
when about to take reading and to bring it to rest quickly
Procedure:
1. Four ranging rods are fixed at different points i.e. A, B, C, D etc. such that they
should be mutually visible and may be measured easily.
2. Measure the distance between them.
3. At point A the prismatic compass is set on the tripod Stand, centering and leveling
is then properly done.
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4. The ranging rod at B is ranged through sighting slits and objective vane attached
with horse hair and reading on prismatic compass is noted down.
5. It is fore bearing of line AB. Then the prismatic compass is fixed at B and ranging
rod at C and A are sighted. Reading is taken as forbearing of BC and back bearing
of AB.
6. Repeat the same procedure at stations C, D etc.
Observations and calculations:
Line
Fore
Bearing
Back
Bearing
Difference
Local
attraction
Error
Correction
Difference
Local
attraction
AB
BC
CD
DA
Station
A
B
C
D
Check =(2n-4)x90 0
Result:
Included angle at station A =
Included angle at station B =
Included angle at station C =
Included angle at station D =
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Corrected
bearings
FB
BB
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EXP.NO.4: FLY LEVELLING
Aim: To determine the elevation of a point with respect to reference elevation by Fly
Levelling
Equipment: Dumpy level, leveling staff
Theory:
 The art of determining and representing the relative height or elevation of different
object/points on the surface of earth is called leveling.
 It deals with measurement in vertical plane.
 By leveling operation, the relative position of two points is known whether the points
are near or far off.
 Similarly, the point at different elevation with respect to a given datum can be
established by leveling.
Procedure:
1.
2.
3.
4.
Assume the bench mark and its reduced level from the datum
Set up the instrument at a point and level the instrument
First, take the staff reading on the BM and note it as BS at BM/1 st station
Take the staff reading at next station and note it as FS if instrument position will
be changed or else note it as IS.
5. If instrument position is changed due to obstruction in proper vision, then BS will
be taken on the previous station and that station is treated as a Change point or
turning point.
6. Steps 3,4,5 are repeated until FS is recorded on last station.
Formulae:
Height of instrument (HI) = B.S+R.L of BM
Reduced level (R.L) at a station = H.I – (I.S or F.S)
Observations and calculations:
Station
1
2
3
BS
IS
FS
HI
R.L
REMARKS
CHECK:
The difference between the sum of back sight and the sum of fore sight = the difference
between the last R.L. and the first R.L.
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EXP.NO.5: SENSITIVITY OF BUBBLE TUBE
Aim: To determine sensitivity of bubble tube of a dumpy level.
Equipment: Dumpy level, leveling staff
Theory:
 The level or bubble tube gives the direction of horizontal plane because the surface of
a still liquid at all points is at right angles to the direction of gravity.
 A liquid of low viscosity such as alcohol, chloroform or sulphuric ether is used in
bubble tube.
 The sensitiveness of a level tube is defined as the “angular value” of one division
marked on the tube.
 It is the amount the horizontal axis has to be tilted to cause the bubble to move from
one graduation to another.
Procedure:
1. Set the instrument at O and level it accurately.
2. Sight a staff kept at C, distant D from O. Let the reading be CF.
3. Using a foot screw,deviate the bubble over ‘n’ number of divisions and again sight
the staff. Let the reading be CE.
4. Find the difference between the two staff readings. Thus
s = CE – CF.
from triangle BEF, we have
tan α ≈ α ≈ s/D
similarly, from triangle AOB,
α = AB/R = nl/R
where R = radius of curvature of the bubble tube
l = length of one division on the bubble tube (usually 2 mm)
equating,
s/D = nl/R
sensitivity of bubble tube = l/R
= (s/ND) radians
= (s/ND) seconds.
RESULT:
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EXP.NO.6: CONTOURING AND ITS PLOTTING
Aim: To plot and survey various points for making a contour map of an area.
Equipment: Dumpy level, leveling staff
Theory:
 A contour is an imaginary line on the ground joining the points of equal elevation.
 It is a line in which the surface of ground is intersected be a level surface.
 The vertical distance between any two consecutive contours is called “contour
interval”.
 The horizontal distance between two points on two consecutive contours is known as
the “horizontal equivalent”
Procedure:
1.
2.
3.
4.
5.
6.
7.
Choose the ‘contour interval’, depending on the type of ground.
Divide the area such that various points at regular intervals can be surveyed.
Assume the bench mark and its reduced level from the datum
Set up the instrument at a point and level the instrument
First, take the staff reading on the BM and note it as BS at BM/1 st station
Take the staff readings at regular intervals. Note their horizontal distances.
Plot the values onto a drawing sheet and obtain the contour lines.
Formulae:
Height of instrument (HI)= B.S+R.L of BM
Reduced level(R.L) at a station= H.I – (I.S or F.S)
Observations and calculations:
Station
1
2
3
BS
IS
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FS
HI
R.L
REMARKS
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EXP.NO.7: STUDY OF THEODOLITE
Aim: To study the terminology and temporary adjustments in theodolite surveying
TERMINOLOGY:
VERTICAL AXIS:
It is the axis about which the telescope can be rotated in a horizontal plane.
HORIZONTAL AXIS:
It is the axis about which the telescope can be rotated in a vertical plane.
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LINE OF COLLINATION:
It is the imaginary line joining the intersection of the cross hairs of the diaphragm to the
optical center of the object glass and its continuation.
AXIS OF THE TELESCOPE:
It is the line joining the optical center of the object glass to the center of the eye-piece.
AXIS OF THE LEVEL TUBE:
It is the straight line tangential to the longitudinal curve of the level tube at the center of the
tube.
CENTERING:
The process of setting the theodolite exactly over the station mark is known as centering.
TRANSITING:
It is the process of turning the telescope in vertical plane through 180º about the trunnion
axis.
DESCRIPTION OF EQUIPMENT:
TELESCOPE:
It consists of eye-piece , object glass and focusing screw and it is used to sight the object.
VERTICAL CIRCLE:
It is used to measure vertical angles.
LEVELLING HEAD:
It consists of two parallel triangular plates called tribrach plates.
Its uses are
1. To support the main part of the instrument.
2. To attach the theodolite to the tripod.
LOWER PLATE:
It consists of lower clamp screw and tangent screw.
UPPER PLATE:
The upper plate is attached to the inner axis and it carries two verniers. It consists an upper
clamp screw and tangent screws. These screws are used to fix upper plate with lower plate
accurately.
FOOT SCREWS:
These are used to level the instrument
PLUMB BOB:
It is used to center theodolite exactly over the ground station mark.
SWINGING THE TELESCOPE:
It means turning the telescope about its vertical axis in the horizontal plane. A swing is called
right or left according as the telescope is rotated clockwise or counter clockwise.
FACE LEFT:
If face of the vertical circle is to the left side of the observer, then the observation of the
angles taken is known as face left observation.
FACE RIGHT:
If the face of the vertical circle is to the right side of the observation, then the observation of
the angles taken is known as face right observation.
CHANGING FACE:
It is an operation of bringing the face of the telescope from left to right and vice-versa.
TEMPORARY ADJUSTMENTS:
There are three temporary adjustments of a theodolite. They are
1. Setting up the theodolite over a station.
2. Leveling up.
3. Elimination of parallax.
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1. SETTING UP:
It includes two operations
1. Centering a theodolite over a station: Done by means of plumb bob.
2. Approximately leveling it by tripod legs only: Done by moving tripod legs radially
or circumferentially.
2. LEVELING UP:
Having centered and approximately leveled the instrument, accurate leveling is done
with the help of foot screws with reference to the plate levels, so that the vertical axis shall be
truly vertical.
To level the instrument the following operations have to be done.
1. Turn the upper plate until the longitudinal axis of the plate level is roughly parallel to
a line joining any two of the leveling screws (A & B).
2. Hold these two leveling screws between the thumb and first finger of each hand
uniformly so that the thumb moves either towards each other or away from each
other until the bubble comes to the center.
3. Turn the upper plate through 90º i.e until the axes of the level passes over the position
of the third leveling screw ‘C’.
4. Turn this leveling screw until the bubble comes to the center.
5. Rotate the upper plate through 90º to its original position fig(a) and repeat step(2) till
the bubble comes to the center.
6. Turn back again through 90º and repeat step 4
7. Repeat the steps 2 and 4 till the bubble is central in both the positions.
8. Now rotate the instrument through 180º. The bubble should be remaining in the center
of its run, provided it is in correct adjustment. The vertical axis will then be truly
vertical.
3. ELIMINATION OF PARALLAX:
Parallax is a condition arising when the image formed by the objective is not in the
plane of the cross hairs. Unless parallax is eliminated, accurate sighting is not possible.
Parallax can be eliminated in two steps.
a. FOCUSSING THE EYE-PIECE:
Point the telescope to the sky or hold a piece of white paper in front of the telescope.
Move the eyepiece in and out until a distant and sharp black image of the cross-hairs is seen.
b. FOCUSSING THE OBJECT:
Telescope is now turned towards object to be sighted and the focusing screw is turned
until image appears clear and sharp.
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EXP.NO.8: REPETITION METHOD
Aim: To measure an horizontal angle by repetition method.
Theory:
In this method, the angle is added several times mechanically and the value of the
angle is obtained by dividing the accumulated reading by the number of repetitions.
Equipments: Transit thodolite, tripod and ranging rods(2no.s).
Procedure:
1. Set up the instrument over ‘O’ and level it accurately.
2. With the help of upper clamp and tangent screw, set 0º reading on vernier ‘A’. Note
the reading of vernier ‘B’.
3. Release the upper clamp and direct the telescope approximately towards the point ‘P’.
Tighten the lower clamp and bisect point ‘P’ accurately by lower tangent screw.
4. Release the upper clamp and turn the instrument clock-wise towards Q. Clamp the
upper clamp and bisect ‘Q’ accurately with the upper tangent screw. Note the readings
of verniers ‘A’ and ‘B’ to get the values of the angle POQ.
5. Release the lower clamp and turn the telescope clockwise to sight P again. Bisect P by
using the lower tangent screw.
6. Release the upper clamp, turn the telescope clockwise and sight Q. Bisect Q by using
the upper tangent screw.
7. Repeat the process until the angle measured (required number of times is 3). The
average angle with face left will be equal to final reading divided by three.
8. Change face and make three more repetitions as described above. Find the average
angle with face right, by dividing the final reading by three.
9. The average horizontal angle is then obtained by taking the average of the two angles
with face left and face right.
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EXP.NO.9: REITERATION METHOD
Aim: To measure an horizontal angle by reiteration method.
Equipments: Transit Theodiolite , Tripod and Ranging rods.
Procedure:
1. Set the instrument over “O” and level it set the Vernier to zero and bisect point A
accurately.
2. Loose the upper clamp and turn the Telescope clockwise to point B. Bisect B by using
the upper tangent screw. Read both the Verniers, the mean of the Verniers will give
the angles AOB.
3. Similarly, bisect successively C, D etc, thus closing the circle. Read both the verniers
at each bisection.
4. Finally sight to A, the reading of the vernier should be the same as the original setting
reading.
5. Repeat the steps 02 to 04 with other face i.e. face Right.
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EXP.NO.10: HEIGHT OF AN OBJECT
Aim:
To determine the height of an object by measuring vertical angle and distance to its base.
Equipments :
1. Theodolite
2. Leveling Stop
3. Tape or Chain
4. Pegs
5. Plumb bob
Procedure:
1. Setup the instrument at station P.
2. Perform all temporary adjustments.
3. Bring the line of collimation horizontal
4. Enter the initial readings in the tabular form.
5. Swing the telescope and take staff reading over the given B.M.
6. Swing the telescope towards the object.
7. Release the vertical clamp screw, sight the top of the object Q1, and clamp the vertical
clamp screw.
8. Read C and D verniers and enter the readings.
9. Release the vertical clamp screw, sight the bottom of the object Q, and clamp the screw.
10. Read vernier readings and enter in the tabular form.
11. Measure the Horizontal distance between the instrument station and the object.
12. The above procedure will be repeated with the face right observation.
13. The average of the two observations by transiting the telescope taken with different
faces will be vertical angle.
14. Calculate the height of the top point Q1 from horizontal line (h1) and height of the
bottom point Q from horizontal line (h2) by using formula h = d tan α
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EXP.NO.11: STUDY OF PLANE TABLE
Aim: To study plane table and its accessories.
Introduction :
Plane table surveying is a graphical method of surveying in which field work and
plotting are done simultaneously in the field.
The plain table consists of the following:
1. Drawing board mounted on a tripod
2. Straight edge called an alidade.
Drawing board:
The board is made of well-seasoned wood and varies in size from 40cm x 30 cm to
75cm x 60cm or 50 – 60 cm square.
Alidade:
The alidade consists of metal or box wood straight edge or ruler about 50cm long.
Accessories to the plane table
1. Trough compass
2. U – frame or plumbing fork
3. Water proof cover.
4. Spirit level or level tube
5. Drawing sheet
6. Pencil or eraser
Trough compass: The compass is used to mark the direction of the
meridian on the paper.
U- frame or Plumbing fork:
U frame with a plumb bob used for centering the table.
Water Proof Cover:
Water Proof cover protects the sheet from rain.
Spirit level or level tube:
A level tube is used to level the plane table.
Drawing sheet:
The drawing sheet is fixed on the top of the drawing board.
Pencil and eraser:
A pencil is used for constructing lines and eraser is used for
erasing lines after completion of the plan.
SETTING UP THE PLANE TABLE
Setting up the plane table includes the following three operations.
1. Centering the plane table
2. Leveling the plane table
3. Orientation of plane table
Centering the plane table:
The table should be set up at a convenient height for working say about 1m. The legs
of tripod should be spread well apart and firmly fixed in to the ground. The table should be
approximately leveled by tripod legs and judging by the eye. Then the operation of centering
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is carried out by means of U-frame and plumb bob. The plane table is exactly placed over the
ground station by U-frame and plumb bob.
Leveling the plane table:
The process of leveling is carried out with the help of level tube. The bubble of level
tube is brought to center in two directions, which are right angles to each other. This is
achieved by moving legs.
Orienting the table:
The process of keeping the plane table always parallel to the position, which is
occupied at the first station, is known as orientation. When the plane table is oriented, the
lines on the board are parallel to the lines on the ground.
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EXP.NO.12: RADIATION METHOD
Aim: Setting up the plane table and plotting few objects by radiation method.
Instruments:
1) Plane table
2) Tripod
3) Alidade
Radiation:
The plane table is set up over only one station from which the whole traverse can be
commanded. It is suitable for survey of small areas.
Procedure:
1) Select a point “O” so that all points to be located are visible from it.
2) Set up the table at “O”, level it, and do centering.
3) Select a point “O” on the sheet so that it is exactly over station “O” on the
ground.
4) Mark the direction of the magnetic meridian
5) Centering the alidade on “O” bisect the objects of traverse A, B, C and D
6) Measure the distances OA, OB, OC and OD
7) To convenient scale plot a, b, c and d respectively on drawing sheet
8) Join the points a, b, c and d on the drawing sheet
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EXP.NO.13: INTERSECTION METHOD
Aim: Plotting building and other features by Intersection method.
Instruments:
1) Plane table
2) Tripod
3) Alidade
Procedure:
1. Select two points P and Q such that the points (building corners) to be plotted are
visible from their stations. Set the table on P and locate P on the sheet.
2. With the help of the trough compass, mark the north direction on the sheet
3. Pivoting the alidade about p, sight it to Q.
4. Measure the distance PQ and locate Q on the sheet to a convenient scale. Now pq is
known as the base line.
5. Pivoting about ‘p’ bisect the inaccessible objects A and B (building corners) and
draw rays.
6. Shift the table to ‘Q’ and make temporary adjustments.
7. Place the alidade along qp and the rotate the table till p is bisected.
8. Pivoting about bisect the objects A and B and draw rays.
9. The intersection of rays drawn from P and Q will give the points a and b.
10. To check the accuracy, compare measured AB with plotted distance ab.
11. The same procedure is applied for other features, each point is bisected from two
stations.
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EXP.NO.14: TWO POINT PROBLEM
Aim: Location of the position on the plan, of the station occupied by the plane table by means
of observations to two well defined points whose positions have been previously plotted on
the plan.
Instruments:
1) Plane table
2) Tripod
3) Alidade
.
Procedure:
1) Select an auxiliary station R such that P,Q and S are clearly visible from R and the
angles formed by P,Q, and S are not very accurate.
2) Set up the plane table at R. Level the table. Approximately orient the table so that
p-q is nearly parallel to P-Q . Clamp the table in this position.
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3) Plot the position of R on the table by sighting to P and Q. For this, keep the alidade
against p and sight the signal at P. Draw a line along the ruling edge of the alidade.
Similarly, sight Q by pivoting the alidade against q and draw a ray . The intersection
of the two rays drawn gives the position of the station occupied by the table. Label
this point r. Point r is obtained as the position of the station occupied and is accurate
to the extent the line p-q is parallel to P-Q.
4) Transfer the point r on the table to the ground as R using the plumbing fork. A peg
can be driven to locate the ground station.
5) With alidade kept against r , sight the ranging rod or the other signal at S and draw
a line. Mark the distance S by approximation or rough chaining. Point s1 is thus
obtained.
6) Shift the table to S. Level and center table over s1. Orient the table by back sighting
at R. For this keep the alidade against s1 and sight the signal at R by rotating the table.
Clamp the table in the position.
7) With the alidade kept against p, sight the station P and draw a ray. This ray
intersects the line r-s at s, giving the stations. Keep the alidade against s, sight the
signal at Q, and draw a ray. This ray will intersect the ray r-q not at q but at q’, as the
orientation of the table is only approximate.
8) p-q’ is the representation obtained of p-q due to the error in orientation. The angle
q-p-q’ is the angular error in orientation.
9) To remove this error, place the alidade against p-q’ and keep a ranging a rod at
large distance M.
10) Keep the alidade against p-q and rotate the table until the signal at M is sighted
and clamp the table. This position is the correct oriented position, with P-Q parallel to
p-q.
11) Obtain the position of S by sighting P and draw a ray. Keep the alidade against q
and sight the signal at Q. The intersection of the two ray’s gives true positions of S.
the distance of M must be large enough to correct the orientation of the table.
SURVEYING FIELD WORK-I MANUAL/MADHAVA.N/CIET,RAIPUR
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EXP.NO.15: THE THREE POINT PROBLEM
Aim: Location of the position on the plan, of the station occupied by the plane table by
means of observations to three well defined points whose positions have been previously
plotted on the plan.
Instruments:
1) Plane table
2) Tripod
3) Alidade
PROCEDURE:
1) Set up the plane table at the station S. Join p-q and q-r.
2) Draw a perpendicular to p-q at p. Keep the alidade along this perpendicular, rotate the
table and sight the signal at P, with p towards P. Once P is sighted, clamp the table.
3) Keep the alidade against q and adjust it to sight the signal at Q. Draw a line along the
ruling edge. This line intersects the perpendicular to p-q at t.
SURVEYING FIELD WORK-I MANUAL/MADHAVA.N/CIET,RAIPUR
29
4) Draw a perpendicular to q-r at r. Keep the alidade along this perpendicular, rotate the
table and sight the signal at R , with r towards R. Clamp the table.
5) Keeping the alidade against q, direct the line of sight to Q. When Q is sighted, draw a
ray along the ruling edge. This line intersects the perpendicular drawn at r at u.
6) The plot of station S is on the line t-u. To locate s, drop a perpendicular from q to tu.The foot of the perpendicular is the station s.
7) To orient the table, keep the alidade along s-p and sight the signal at P by rotating the
table. Clamp the table, which is now oriented.
8) To check the orientation, sights can be taken to Q and R, both of which should pass
through s if the orientation is correct.
SURVEYING FIELD WORK-I MANUAL/MADHAVA.N/CIET,RAIPUR