Surveying Observation, Surveying, Observation
Surveying Observation, Surveying, Observation
Surveying Observation, Surveying, Observation
3
Prepared by Er.JEBASTIN THANASEKAR J Page 43
EX NO 2 DATE:
MEASUREMENT OF HORIZONTAL ANGLE
REITERATION METHOD
AIM :
To measure the horizontal angles between objects say A, B, C, D and E from a particular
station O
INSTRUMENT REQUIRED:
Theodolite with accessories
PROCEDURE
1) Set up the instrument at point O and do all the temporary adjustments and level it
accurately.
2) Set the vernier A to zero by using upper clamp and its tangent screw and then tighten the
upper clamp
3) Direct the telescope object A, bisect it accurately using the lower clamp and its tangent
screw .Now check whether it still reads 0
o
or not
4) Loosen the upper clamp screw, turn the telescope in clock wise direction and bisect the
right hand object B exactly by using upper clamp and its tangent screw.
5) Read both verniers A and B. The mean of the two vernier readings will give the angle
AOB
6) Similarly bisect B, C, D and E. Read both the veniers at each bisection. Find the values
of included angles.
7) Finally close the horizon by sighting towards the initial point. Now the vernier should
read 360
o
if not note down the closing error
RESULT:
The horizontal angles between various objects are .
Prepared by Er.JEBASTIN THANASEKAR J Page 44
Observations
VERTICAL ANGLE
Face least count
Face least count
Fig 3: Vertical angle
Instrument
station
Sight to
Vernier scale A Vernier scale B mean
o
o
Instrument
station
Sight to
Vernier scale A Vernier scale B mean
o
o
O
Level line
B
U
I
L
D
I
N
G
Prepared by Er.JEBASTIN THANASEKAR J Page 45
EX NO: 3 DATE:
MEASUREMENT OF VERTICAL ANGLE
AIM:
To find the vertical angle of an elevated object.
INSTRUMENT REQUIRED:
Theodolite with accessories
PROCEDURE
1) Set up the instrument at station point O and level it accurately with reference to the
altitude level.
2) Keep the altitude level parallel to any two foot screws and bring the bubble to the center.
3) Rotate the telescope through 90
o
till the altitude bubble is on the third foot screw.
4) Bring the bubble to the center using third foot screw. Repeat the procedure till the bubble
is center at both the position.
5) Loose the vertical circle, clamp and rotate the telescope in vertical plane to sight the
object.
6) Read both veniers C and D of the vertical circle.
7) Now transit the telescope towards the required position of the object (ie) towards the top
of the tower and clamp the screw.
8) Read both veniers C and D of the vertical circle and the mean of these two readings gives
the actual vertical angle.
RESULT:
The vertical angle of the elevated point =
Prepared by Er.JEBASTIN THANASEKAR J Page 46
Observations
VERTICAL ANGLE
Face least count
Fig4 :vertical angle
Instrument
station
Sight to
Vernier scale C Vernier scale D mean
o
o
D
Level line
h
BM
O
V
Prepared by Er.JEBASTIN THANASEKAR J Page 47
EX NO: 4 DATE:
BASE ACCESSIBLE METHOD
AIM:
To find the elevation of an object, when its base is accessible.
INSTRUMENT REQUIRED:
Theodolite with accessories
PROCEDURE
1) Set up the instrument at station point O and level it accurately with reference to the
altitude level.
2) Take a staff reading S on the bench mark with line of sight being horizontal so as to
determine the elevation of line of sight.
3) Now direct the telescope towards the object and observe the vertical angle
4) Average value of face left and face right observations will give the actual vertical angle.
Note:
Face left and face right observations should be taken to eliminate the instrumental error.
h=D tan
2
Thus height of object Q above the horizontal line of sight ie QQ is determined.
FORMULA USED:
RL of Q =RL of BM +staff reading over BM +vertical component
RESULT:
RL of point elevated object =
Prepared by Er.JEBASTIN THANASEKAR J Page 48
EX NO: 5 DATE:
SINGLE PLANE METHOD
AIM:
To find the elevation of an object Q, when its base is inaccessible.
INSTRUMENT REQUIRED:
Theodolite with accessories
Measuring tape
Levelling staff
PROCEDURE:
1) Set up the instrument at station point O and level it accurately with reference to the
altitude level.
2) Direct the telescope with face left towards the top of the object Q. Bisect accurately and
read both C and D verniers to determine the vertical angle
1.
3) Change the face to right and again measure vertical angle
1.
4) Set the vertical circle verniers to read zero and altitude bubble centered, take a staff
reading S
1
on the staff held on BM.
5) Shift the instrument to the new position R at a distance b from O. Set up and level it
accurately.
6) Now measure the vertical angle
2
by taking both face left and face right observations.
7) Set the vertical circle verniers to read zero and altitude bubble center take a staff reading
S
2
on the staff held on BM.
FORMULA USED:
RL of Q =RL of BM+staff reading over BM. +V
1
RL of Q =RL of BM+staff reading over BM. +V
2
D =S+b tan 2/ (tan
1
-tan
2
)
.
Prepared by Er.JEBASTIN THANASEKAR J Page 49
Observations
VERTICAL ANGLES
Face least count
Instrument
station
Sight to
Vernier scale C Vernier scale B mean
o
o
Instrument
station
Sight to
Vernier scale C Vernier scale D mean
o
o
Prepared by Er.JEBASTIN THANASEKAR J Page 50
HILL
Fig5: single plane method
Calculation:
RESULT:
RL of top of hill=
Level line
1
BM
2
P1
P2
b
V1 V2
S
Prepared by Er.JEBASTIN THANASEKAR J Page 51
EX NO: 6 DATE:
TANGENTIAL METHOD OF TACHEOMETRY
(BOTH ANGLES ARE IN ELEVATION)
AIM:
To find the elevation of an object Q, when both angles are in elevation.
INSTRUMENT REQUIRED:
Theodolite with accessories
Leveling staff
PROCEDURE
1) Set up the instrument at station point O and level it accurately with reference to the
altitude level.
2) Hold the levelling staff on BM and take the staff reading on it say h
3) Again set the vertical circle to read zero and level it with reference to altitude level.
4) Hold the levelling staff over the required object Q and fix two target points A and B with
a fixed interval S (say 2.5m)
5) Now direct the telescope towards the top target A, get the axial hair ray coincide with top
target A and measure the angle
1
with face left and face right.
6) Again set the vertical circle to read zero and direct to the bottom target B with axial hair
coincides with target B, and measure the vertical angle
2
with face left and face right
observations.
FORMULA USED:
V = D tan
2
S+V = D tan
1
D = s/ (tan
1
-tan
2
)
RL of Q =RL of BM +Height of Inst.(h)+V1
RL of Q =RL of BM +Height of Inst.(h)+V2
Prepared by Er.JEBASTIN THANASEKAR J Page 52
Fig6: Both angles are in elevation
RESULT:
RL of top of hill=
s
A
B
P
h
D
V
2
r
Level line
Prepared by Er.JEBASTIN THANASEKAR J Page 53
EX NO 7 DATE:
TANGENTIAL METHOD OF TACHEOMETRY
(BOTH ANGLES ARE IN DEPRESSION)
AIM:
To find the elevation of an object Q, when both angles are in depression.
INSTRUMENT REQUIRED:
Theodolite with accessories
Levelling staff
PROCEDURE
1) Set up the instrument at station point O and level it accurately with reference to the
altitude level.
2) Hold the levelling staff on BM and take the staff reading on it say h
3) Again set the vertical circle to read zero and level it with reference to altitude level.
4) Hold the leveling staff over the required object Q and fix two target points A and B with
an interval s(say 2.5m)
5) Now direct the telescope towards the top target A, get the axial hair ray to coincide with
top target A and measure the angle
1
with face left and face right.
6) Again set the vertical circle to read zero and direct the bottom target B to coincide with
axial hair and measure the vertical angle
2
with face left a face right observations.
FORMULA USED:
V = D tan
2
S+V = D tan
1
D = s x tan 2/ (tan
1
-tan
2
)
RL of Q =RL of BM1+Hight of Inst. +V1
RL of Q =RL of BM2+Hight of Inst. +V2
Prepared by Er.JEBASTIN THANASEKAR J Page 54
Fig 7: both angles are in depression
RESULT:
RL of top of hill=
Level line
B
A
Q
1
V
Q
r
s
P
1
2
D
Prepared by Er.JEBASTIN THANASEKAR J Page 55
EX NO 8 DATE:
SUBTENSE TACHEOMETRY
AIM:
To determine the horizontal distance between two stations using subtense bar.
INSTRUMENT REQUIRED:
Theodolite with accessories
Subtense bar
arrows
PROCEDURE
1) Set up the instrument at station point P and level it accurately with reference to the
altitude level.
2) Place the subtense bar over the station Q and fix the targets or vanes with a minimum of
3m intercept.
3) Set the vernier A of theodolite to read zero and direct the telescope to bisect the target at
one end of the subtense bar, the vernier A reading zero only.
4) Turn the telescope to bisect the target at other end of the subtense bar.
5) Thus the horizontal angle between these two targets is measured and is taken as .
6) Convert these horizontal angles in terms of seconds.
7) Apply the following formula to find out the horizontal distance D.
FORMULAS USED:
D =
S
X 206265
Where is in seconds
Fig 8: subtense tachometry
RESULT: The horizontal distance between the two stations=..m
A
B
S
D
P
Prepared by Er.JEBASTIN THANASEKAR J Page 56
EX NO 9 DATE:
SETTING OUT OF FOUNDATION
AIM:
To set out the outline of foundation trench for the given room dimension.
INSTRUMENT REQUIRD:
Theodolite with accessories
Tape
Ranging rod
Arrows and thread
PROCEDURE
1) Set the instrument over the station point A and do all the temporary adjustments.
2) Set the vernier A to read zero and focus the line AC and fix the ranging rods at point B
and C with the help of tape.
3) Turn the telescope to 90
o
anticlockwise and focus the line AF and fix the ranging rod at
F.
4) Shift the instrument to the station point B and make the vernier A to read zero by
focusing the line BC and turn the telescope 90
o
anti clock wise and fix the point E.
5) Shift the instrument to the station point C and make the vernier A to read zero by
focusing the line CA and turn the telescope 90
o
anti clockwise and fix the point D.
6) Shift the instrument to the station point D and make the vernier A to read zero by
focusing the line DC and turn the telescope 90
o
anticlockwise and check whether the
point E and F are in same line.
7) Remove the ranging rods and fix the arrows by stretching a line at a distance for half the
width of the foundation.
8) Then with the help of tape, mark the foundation offset side by side of the center line.
9) Repeat the offset marking for all the center lines.
Prepared by Er.JEBASTIN THANASEKAR J Page 57
A B C
6m x 4 m 8m x 4 m
F E D
Fig 9: setting out of foundation
Check:
Calculation Check for diagonal length:
Using the relation AE
2
=AF
2
+FE
2
RESULT:
Thus the outline of the foundation trench has been set up for the room of given size.
Prepared by Er.JEBASTIN THANASEKAR J Page 58
EX NO: 10. DATE:
SETTING OUT OF SIMPLE CIRCULAR CURVE
LINEAR METHOD
AIM:-
Setting out of simple circular curve by offsets from chord produced method
INSTRUMENT REQUIRD:
Theodolite with accessories
Tape
Ranging rod
Arrows and thread
PROBLEM:
Set out a simple circular curve of radius 100m and length of long chord 60 m by offset
from long chord method.
PROCEDURE:
Draw a straight line T
1
T
2
using tape, arrows and ranging rods for a distance of 60m.
Fix the arrows for every 5m on line T
1
T
2
By coordinating with T
1
T
2
mark OX
1
perpendicular to a point 5 m from D
Then for a distance of 10m, produce OX
2
perpendicular to T
1
T
2
.produce the same for
every points of equal intervals.
Thus the simple curve is produced and curve is drawn using tape.
Calculation:
By offset from long chord method,
Offset at a point 0
o
=R _R
2
(
L
2
)
2
Similarly offset with X meter interval
O
x
= R
2
X
2
-(R-O
o
)
Prepared by Er.JEBASTIN THANASEKAR J Page 59
L
R R
Fig 10: setting out of simple circular curve linear method (model figure)
RESULT:
Simple circular curve for radius 100m and length of long chord 80m by offset from long
chord method is done.
T
1
T
2
O
Prepared by Er.JEBASTIN THANASEKAR J Page 60
EX NO :11 DATE:
SETTING OUT OF A TRANSITION CURVE
AIM :
To set a transition curve (cubic spiral) from the following data by the method of deflection
angles.
INSTRUMENT REQUIRD:
Theodolite with accessories
Tape
Ranging rod
Arrows and thread
PROBLEM:
Length of the transition curve L=20m
Radius of circular curve R=50m
Peg interval l=2.5m
PROCEDURE:
Set the instrument over the station point A and do all the temporary adjustments.
Set the vernier A to read zero, bisect the ranging rod and fix the point B. This point is a
reference point for a straight arc.
By loosening the upper screw rotate the telescope clockwise and set deflection angle
1
and clamp both the screws.
From A take the first chord length in the tape and bisect the line of collimation using a
ranging rod and fix the point P
1
, on the ground.
Take the second deflection angle
2,
from the point A take the second chord length in
the tape, and use the ranging rod to fix the point P
2
on the ground.
Similarly repeat the whole steps to get the points like P
3
, P
4
etc.
J oin all the points to get the required curve.
As a check, calculate the spiral angle --, this should be three times the least deflection
angle.
Check
Delta s =1719 L/R
Prepared by Er.JEBASTIN THANASEKAR J Page 61
Fig 11: setting out of transition curve(model figure)
RESULT:
Thus setting out of transition curve is done in the field by using the given data.
1,
A
B
Transition curve
1,
Tangent line
Prepared by Er.JEBASTIN THANASEKAR J Page 62
EX NO: 12 DATE:
SETTING OUT OF A SIMPLE CURVE
USING RANKINES METHOD
Aim :
To range the curve at the field using theodolite from the following datas using Rankines
method.
INSTRUMENT REQUIRD:
Theodolite with accessories
Tape
Ranging rod
Arrows and thread
PROBLEM:
Radius of curve = 15m
Intersection angle = 100
o
Peg interval = 2m
Chainage at intersection point =200m
PROCEDURE:
Set the theodolite at the point of curve (T
1
). With both plates clamped to zero, direct the
theodolite to bisect the point of intersection (V). The line of sight is thus in the direction
of the rear tangent.
Release the vernier plate and set angle /\
1
on the vernier. The line of sight is thus directed
along chord T
1
A.
With the zero end of the tape pointed at T
1
and arrow held at a distance T
1
A=c along
chord T
1
A =c along it, swing the tape around T
1
till the arrow is bisected by the cross
hairs. Thus, the first point A is fixed.
Set the second deflection angle /\
2
on the vernier so that the line of sight is directed
along T
1
B .
With the zero end of the tape pinned at A, and an arrow held at distance AB =C along it,
swing the tape around A till the arrow is bisected by the cross-hairs thus fixing the point
B.
Repeat the steps (4) and (5) till the last point T
2
is reached.
Prepared by Er.JEBASTIN THANASEKAR J Page 63
Check:
The last point so located must coincide with the point of tangency (T2) fixed independently by
measurements from the point of intersection. If the discrepancy is small, last few pegs may be
adjusted.
R
R
o
3
2
1
T1
C
V
A
B
Fig 12: setting out of a simple curve using Rankines method
RESULT:
Thus setting out of curve by Rankines method is done in the field by using the given
data.