1

1.GENERAL INTRODUCTION
In order to enable students to practice different
surveying instruments; to inculcate in them
leadership quality, co-ordination of work, team
management and to face practical difficulties in
field and life, a training for one month is provided
to them on some hilly tract. This training known as
Survey Camp forms an essential part of their
study curriculum. The survey camp is held in
prefinal or final year of Civil Engg. trade
generally to achieve the following objectives:
(a) To impart intensive training to the students to
learn and use
different types of surveying
instruments.
(b) To make students conversant with the camp
life.
(c) To train them properly to face
difficulties while surveying in the field.

practical

(d) To make them adapt to local condition and

people of different culture.
(e) To provide opportunity to develop team spirit in
them.
(f) To train them for self-management.

(g) To enable them to learn co-ordination of work

within the group and between different groups.
Although different objectives have been listed
above, but Survey Camp has well defined purpose
i.e. to prepare topographical map of an area
showing different physiographical features. The
general
between
an
ordinary
map
and
topographical map is the depiction of contour lines
in a topographic map showing elevation and
depression of area.

1.1. SITE SELECTION

Survey camp can be concluded on any site. But
surveying on some hilly tract for practicing is
always advantageous. The students not only learn
to survey difficult tracts and routes but such a
location is also quite suitable to draw the contours
of the area.
The following features are essential to make
any selected sitean ideal one:
(a) A road or railway line adjoining or at nearby site
for establishment of permanent bench mark.
(b) Elevation or depression of some part to draw
the contour of the area.

(c) Some important features like overhanging cliff,

vertical cliff, ridge, valley etc.
(d) Buildings, ponds, orchards, roads and other
features to draw the objects properly.

Site or location on which survey

camp was held:HILL TOP AREA OF AP GOYAL UNIVERSITY

1.2. SURVEY CAMP WORK

The whole work of survey camp is mainly divided
into following parts:
(a) Field work
(b) Plotting work
For doing field work, the students are divided into
different groups and each group is allotted work
independently. The spirit of competition develops
enthusiasm in students and each group tries its
best, toils hard and work with determination and
sincerity to perform better and achieve the final
goal.

1.3. FIELD WORK

The field work in the survey camp is divided into

following phases:
1. Theodolite Traversing
2. Plane table Survey
3. Contouring

1.3.1.Theodolite Traversing: In Theodolite

traversing, first of all reconnaissance is done and
the survey stations or flag points are selected,
keeping in view all the necessary precautions. The
stations should be selected on a firm ground and
should be visible from the forward and backward
station. After choosing the suitable stations, their
location is marked and recorded. The theodolite are
fixed on the respective stations and the angles
measured by repetition method with three
readings, on face left and three readings on face
right respectively. After taking the successive
readings, the mean angle is taken is taken and all
the readings should be entered on the field book.
Fore bearing of a line AB is measured by using
circular compass or tubular compass which is
attached to the Standard of a theodolite by
loosening its screw and fixing the notch of compass

to them and again tightening the screw. From this

measured bearing, bearing of other lines are also
calculated. Lengths of different lines are measured
by stepping method from top to bottom for
accurate results. The different lengths and angles
can be checked by tacheometric surveying.
1.3.2. Plane table surveying: In plane table
surveying intermediate stations are marked to
facilitate the smooth conduct of work between
different stations. Each group performs the plane
table survey of area allotted to It. Some common
area or points are also identified which are to be
surveyed by adjacent groups for overlapping the
entire surveyed area to get the complete map.
Different objects are thus plotted inside as well as
outside the traverse. All important objects are
plotted by radial line method. Far off distant
objects are plotted by intersection method. At
every setting, orientation is done by back sighting
and already plotted work is checked before starting
the work at the forward stations to remove any
crept in error.
The checking is usually done by measuring some
odd distances on the ground by tape and
comparing them with the same plotted objects on
sheet by scale conversion. Plane table survey is

generally finished at the starting point to generate

a closed loop by traversing.
It is the main and central phase of survey camp
which takes the maximum period to complete. It
should be fairly accurate and number of traverse
stations determines the accuracy. More the number
of traverse stations, greater is the accuracy. At the
end of the days work, before shifting of
instruments to the camp office, location of current
traverse station and forward station (where to start
next days work)must be taken.
1.3.3. Contouring: For contouring, a station
having maximum R.L. (Highest point) is selected
such that radial lines can be run from this station in
different directions covering all the stations.
However if the area is large, contour should be run
independently around each respective stations and
joined together to get the complete contour map
.Radial lines are marked in the field with the help of
Alidade and plane table or with the help of an
ordinary theodolite. One or two contours near the
highest point are plotted by direct method for
explanation to the students and remaining work is
completed by following indirect method of
contouring. A suitable common angle is selected
between different radial lines. Reduced levels of

different points at fixed horizontal equivalent along

radial lines are measured with the help of a dumpy
level. Ceylon ghat tracer and Abneys level can be
used for speedy work but accuracy is reduced. All
the values of R.L.s are written on a drawing sheet
fixed on a plane table in the field itself for
subsequent interpolating. The R.L. of highest point
O is fixed by fly leveling by shifting the level from a
nearest permanent bench mark with the help of a
digital dumpy level. If no permanent bench mark is
available R.L. of point O is taken 100.00 or
according to situation as an arbitrary bench mark.

1.4. PLOTTING WORK

The plotting work of survey camp is divided into
following phases:
1. Preparation of Theodolite Traversing sheet.
2. Preparation of Plane Tabling sheet.
3. Preparation of Contour map.
4. Preparation of Topographic map.
1.4.1. Preparation of Theodolite Traversing
Sheet: After the completion of field work, the next
step in the second phase of survey camp is to plot
the details of work done in the field on drawing

sheets as a record. To prepare the theodolite

traversing sheet, first of all, Gales traverse table is
prepared. For this, sum of included angles of
traverse are checked out by (2N-4) rt. angles,
where N is the number of sides of the closed
traverse. The difference between the theoretical
sum and that of measured angles in a closed
traverse is called angular error. This error is equally
distributed in all the measured angles. The reduced
bearings are calculated from W.C.B. and their
quadrants are mentioned. The independent coordinates are calculated by applying any one of
Transit, Bowditch or Third rule formula after
calculating the latitudes and departures. The
traverse is then plotted to a suitable already fixed
scale. The area of closed traverse is calculated by
arranging the co- ordinates in determinant form
and cross multiplying. The relative closing error is
calculated by dividing the closing error by
perimeter of the traverse. The sample of sheet has
been attached in the workbook. Right hand side is
used for printing work giving details of site
location, North direction, Scale etc. Remember, the
longest line between two flag station should be
selected and accurately measured. This line is
known as Base line around which network of

triangles is built. For this, base line measurement

table should be filled and correction applied.
1.4.2. Preparation of Plane tabling sheet: The
plane table sheets of different groups are collected
and the plotted traverse is traced out on a tracing
paper.
When all the drawing sheets of different groups are
traced on different tracing papers, they are
overlapped on common points carefully fixing all
the sheets and jointly tracing into a common sheet
which is generally a superior tracing sheet such as
gateway paper. On right hand side of the sheet, a
margin of 25mm is left for survey sheet heading ,
name block and other particulars etc.
After drawing different objects, oil pastel colours
are used at the back sides of sheet to colour
various object. Very light colours are used to
differentiate different objects according to the
conventional signs but uniformity of colours should
be obtained. Traverse stations should be marked
with a light yellow colour.
1.4.3. Preparation of Contour map: For
preparing contour map, a suitable contour interval
is selected. Now interpolation of contour is started
on a drawing sheet which was prepared in the field

10

with different radial lines emerging from the

highest point. On the radial lines, R.L.s of different
points are subscribed as per the scale and
horizontal equivalent. When difference contours
are interpolated by simple arithmetical method,
they are checked for accuracy by keeping the
traced sheet above the sheet of plane tabling.
Proper contours should indicate distinct features
like valley, ridges, depression, steep slope etc.
coincidal with the sheet features. The value of
different contours should be written at the end and
middle such that they are read from two right
angled directions. Similarly 25mm space is left in
right hand side of sheet for name block, heading
etc. The contour lines should be marked with a
preferable black colour. Selection should be done
by drawing a section line running through the
contour from left to right at suitable location and
distinctive features drawn. The contour map
showing sectional features should be drawn on a
black sheet preferably marked with silver and
golden colours.
1.4.4. Preparation of topographic map: After
preparing all the three necessary sheets i.e.
Theodolite traversing, Plane table survey and
Contouring map ; the fourth and final sheet of

11

Topographical map is prepared. It is a complete

map of any area which clearly represents various
topographical features of area i.e. general
topography of land. It is generally a merger of all
the three sheets.
It is prepared by tracing the different contours on
plane table survey sheet. The theodolite traverse is
also marked showing the different flag stations.

3. THEODOLITE SURVEYING
3.1. INTRODUCTION
A theodolite is mostly used for measuring the
horizontal and vertical angles accurately. In a
theodolite, there are two scales for measuring
horizontal and vertical angles. It is also used to
measure the bearing of a line and to prolong a
survey line. It consist of a telescope which rotates
in the horizontal plane to measure the horizontal
motion on the horizontal graduated circle by
means of horizontal verniers. It can also rotated in
the vertical plane to measure vertical motion on
vertical graduated circle by means of two vernier
attached to vertical circle.

12

3.2. TYPES OF THEODOLITES

There are two types of theodolites:
(a) Transit Theodolite
(b) Non Transit Theodolite
(a)Transit Theodolite: In this, type of
theodolite the telescope can be revolved through
a complete revolution about its horizontal axis in
the vertical plane and now a day, such type of
theodolite are generally in practice.
(b) Non transit Theodolite: In this case, the
telescope cannot be revolved through a complete

13

revolution about horizontal axis and such types

of theodolites are absolute.

3.3. MAIN PARTS OF VERNIER

TRANSIT THEODOLITE
(a) Tripod Stand: It is a three leg stand on
which the theodolite is supported.
(b) Plumb bob: Its main function is to facilitate
centering work and it is hung from a hook
provided at the bottom of the horizontal circle
plates.
(c) Levelling head: It consists of two parts (a)
Center shifting arrangement for quick setting i.e.
centering (b)Tribrach plate with three arms, each
carrying a leveling screw.
(d) Spindles: It is conical in shape and forms
the vertical axis of the instrument. There are two
spindles, one inside the other. The inner spindle
is solid and conical in shape, whereas the outer
one is hollow.
(e) Lower circular plate: It is a plate having
circular shape. It is graduated from angle 0
degree to 360 degree in clockwise direction. The
movement of such plate is done by lower

14

clamping screw and lower tangent screw. When

the clamping screw is tightened, the lower
tangent screw is used for slow motion.
(f) Upper plate: It is attached to the inner
spindle. It is fitted above the lower circular plate
and is also circular in shape. It carries two
verniers with magnifiers placed at angle of 180
degree apart for reading the horizontal angle to a
least count of one minute or 20 seconds.
(g) Level tube: With the help of this, levelling of
the theodolite is done, same as in case of level.
The bubble is brought in the centre of its run
through levelling screws.
(h) Standards: The two uprights are called
standards.
(i) Compass: The circular prismatic compass is
attached above the upper circular plate to
measure the horizontal angle. This compass is
rarely used.
(j) Telescope: The telescope which is fitted is
either external focusing or internal focusing but
now a days, internal focusing telescopes are
preferred.

15

(k) Vertical circle: The two vertical scales like

that of horizontal circle are used to measure the
vertical angle. The vertical circle is divided into
four quadrants. The graduations in each
quadrant are numbered from angle 0 to 90
degree in the opposite direction from the two
zeros placed at ends to horizontal diameter of
the vertical circle so that the line joining the
zeros is parallel to the line of collimation when it
is horizontal.

3.4. IMPORTANT TERMS USED IN

THEODOLITE SURVEY

16

(a) Swinging: It is the turning of telescope in

the horizontal plane.
(b) Transiting: It is the turning of telescope over
its supporting axis through the angle of 180
degree in vertical plane by bringing it upside
down.
(c) Horizontal axis: It is the axis about which
the telescope can be revolved in the horizontal
plane.
(d) Vertical axis: It is the axis about which the
telescope can be revolved in the horizontal
plane.
(e) Line of collimation: It is the imaginary line
joining the intersection of cross hair of the
diaphragm to the optical center of the object
glass.
(g) Face left:When the vertical circle of the
theodolite is on the left of the observer, then it is
called face left.
(h) Face Right: When the vertical circle of the
theodolite is on the right of the observer, then it
is called face right.
(i) Centering: Centering is done by means of
legs of tripod stand so that the hung plumb bob

17

is at the center of the cross, marked on the top of

the driven wooden peg by intersecting the two
diagonals. It can also done by center shifting
device. In hilly areas, two legs downhill and one
leg up hill side is always placed for fixing the
theodolite.
(j) Levelling:Loose all the foot screws so that all
the three are at the centers. Rotate the
instrument and placed it parallel to any two foot
screws. Now move the two foot screws either
inward or outward so that the bubble of the plate
level is at the center. Now move the instrument
perpendicular to the first position i.e. parallel to
the third screw. Then again, same procedure is
followed using the third screw until the bubble is
at the centre. Again repeat the procedure. It is
continued till the bubble is at the centre of its run
in both the cases without using foot screws when
a complete revolution is given.
(k) Focusing: This is done by following two
methods:
(a) Focusing the eye piece: Move the eye piece
so that the two cross wires i.e. horizontal and
vertical can be clearly seen. It is also done by
placing a piece of paper in front of the telescope.

18

(b) Focusing the object glass: It is done with the

help of focusing screw so that clear image of the
object is seen through the eye piece.

3.5.
EQUIPMENTS
USED
THEODOLITE SURVEYING

IN

Following instruments are generally used in

theodolite surveying
(a) Theodolite with Plumb-bob, Stand, Circular or
Tubular compass.
(b) Ranging rods
(c) Wooden pegs
(d) Measuring tape preferably of 30m length
(e) Field book

3.6.
HOW
TO
PERFORM
THEODOLITE SURVEYING IN THE
GIVEN AREA?
During theodolite surveying, work is divided into
following steps :
1.
Reconaissance: It is the preliminary
inspection of the area to be surveyed. It is
generally done by moving in the area along
with survey team for inspecting site and

19

marking the stations temporarily. These are

referred as Flag points. It is referred to as recci
in military language. It is done without the help
of an instrument.
2.
Permanent Marking of stations: After
the reconnaissance, the main stations are
marked in such a way that they could be easily
discovered on the ground. After this, ranging
rods are fixed on that station with colourful
flags so that they become easily visible from a
distance. A square wooden peg after marking
both the diagonal on the top of the peg is
driven in the hole after removing the ranging
rod for fixing theodolite. In this way, stations
are marked.
3.
Location of stations:After marking the
stations, the location of each station is
recorded in the manual book by taking exact
measurements with tape from the respective
station to the nearby well defined objects so
that the station is easily discovered whenever
required. Along with this, also mark the North
direction in the work book using prismatic
compass or any other suitable instrument.
4.
Least count: Note down the least count of
the theodolite which is usually employed.

20

Generally the theodolite having the least count

of 20 seconds is used.
5.
Measurement of angle (Horizontal):
The horizontal angle should be measured by
repetition method because it is the most
accurate method. In traversing method, the
traverse should be run in contour clockwise
direction. In such a method, the error in the
instrument or any other type of error is
eliminated by changing the face of theodolite.
In this method, the theodolite is set up at
station point and the horizontal angle is
measured by seeing the forward station and
the backward station. Three readings are
usually taken with face left and three with face
right. Then the average reading is obtained to
get the true horizontal angle.
6.
Bearing of a line: The bearing of a line
should be noted carefully with the help of
theodolite after fixing the circular or tubular
compass on to the theodolite.
7.
Measurement of distance: The distance
between the two consecutive stations are
noted carefully, with the help of measuring
tapes i.e. firstly measure the distance in the
forward direction and then the same distance

21

in the backward direction and then take the

mean of the two distances.`
8.
Adjustment of angular error: After
measuring all the interior angles of the
traverse, take the sum of all the interior
angles; it should be equal to (2N-4) right
angles. Here N is the number of the sides of
the traverse. If it is not equal to (2N-4) right
angles then the correction is to be applied.
Remember,
Correction=
Correct
Reading-Observed
Reading
Error
= Observed Reading-Correct
Reading
If correction is +ve, error is veand vice versa.
9.
Remarks:(1)The traverse should be in
counter clock wise direction.
(2)Both the verniers are to be read.

4. PLANE TABLE SURVEYING

4.1 INTRODUCTION
After theodolite traversing, second phase of
survey camp i.e.
plane table surveying is started. It is the most
important phase in which different objects and
other photographical features are plotted on the

22

sheet. Plane table surveying is advantageous as

all features plotted on the sheet are present in
the field which can be easily measured,
compared and corrected. So if proper orientation
is followed, chances of error occurring is
minimum.
The disadvantages of plane table survey are as
follow:
1.Different types of loose and cumbersome
accessories are there along with plane table
and the stand which are to be carried in the
field and taken care off.
2.Practically difficult to carry out surveying on a
rainy day. Generally on hilly tracts where
rainfall can occur at any time, it is very difficult
to work on a plane table. Slight shower may
spoil the whole work. To save this, water proof
cover must be kept and carried along with the
other accessories by the surveyor.

23

The different instruments and accessories are:

1.
PLANE TABLE: It is simply like a drawing
board made of Mahogany wood with a brass
clamp at the center on the back side. Clamp is
opened and screwed to stand, on to which the
table is properly fixed. The stand is a tripod
one which can be folded for convenience of
transportation.
The
drawing
board
is
sometimes fitted with a levelling head or a ball
and socket arrangement for the purpose of
levelling. Now a days, plastic plane tables are
also available in the market.
2.
ALIDADE: The alidade is a straight rule
fitted with such an arrangement as to provide
a line of sight. It is used for sighting objects
and drawing rays along one of its beveled

24

edges known as ruling or working or fiducial

edge. The fiducial edge is graduated so as to
serve as a scale of plotting distances. It is
available in two forms (i) Plain alidade and (ii)
Telescopic alidade.
The telescopic alidade is used in the hilly areas
when far off or distant objects are to be plotted
with accuracy.
Accessories: The accessories attached to the
plane table are:
(a) A trough compass, used for making the
direction of the magnetic meridian on the
sheet of the plane table.
(b) A plumbing fork or U-frame with s plumb bob
used for centering the table.
(c) A spirit level for levelling the table.
Besides these, the other accessories are drawing
sheet, a water proof cover to protect the drawing
sheet and common drawing instruments like
pencils, rubber, scale sharpener, drawing pins,
cello tape etc.

4.2. SETTING UP THE TABLE

The setting up of the plane table includes following
three operations:

25

(a) Levelling
(b) Orientation
(c) Centering
To avoid error, setting should be very accurate.
4.2.1. (a) Levelling: Place the table over the
station-point and spread out the legs to make it
level and at a convenient height, preferably not
above the elbow.
Then orient and center the tableapproximately as
explained in the following two operations and
complete the final levelling. The levelling is done
by simply adjusting the legs of the tripod stand.
However for convenience of levelling, sometimes
ball and socket arrangement is fitted on the top of
the table.
4.2.2. (b) Orientation: The table is said to be
oriented when it is so placed that all lines on the
paper are parallel to the corresponding lines on the
ground. This is necessary when more than one
stations have to be occupied by the table as
otherwise, the board would not be kept parallel to
itself at the various stations, and the effect would
be similar to using a different meridian at each
station. There are two methods of orienting the
table viz.

26

(i) By the use of a magnetic needle

(ii) By back sighting
Orientation by back sighting: Suppose the table
is to be set over a station Q represented on the
paper by a point q which has been plotted by
means of a line pq drawn from previous station P.
The orientation consists in bringing qp on the
paper parallel to QP on the ground.
The edge of the alidade is therefore placed along
qp and the table is turned until the point P is
bisected by the line of sight. Then clamp the table
in position.
4.2.3. (c) Centering: The point on the paper
representing the station being occupied should be
vertically over the point on the ground. This
operation is known as centering of the table. This
may be done by means of a plumbing fork or Uframe. To do this, place the pointed end of the fork
touching with the point on the paper and suspend
a plumb bob from the other end. Shift the table
bodily until the plumb bob hangs vertically over the
center of the station peg. If plumb bob is not
available, centering may be done by dropping a
piece of small stone from a point on the underside

27

of the board which is directly under the point on

the paper.
Orientation and centering are inter-related because
when one operation in performed, the other gets
disturbed. Therefore both of them have to be done
simultaneously.

4.3. SCALE SELECTION IN PLANE

TABLING
Scale should be selected in plane tabling work
during the survey camp keeping in view the
extent of the area to be surveyed. However,
approximately base line or maximum length
should be measured by placing method and
scale be decided by measuring the length and
width of the sheet used. But generally 1:1000
or 1cm = 10m is sufficient. But if the area to be
surveyed is small, scale of 1:500 or 1cm = 5m
is selected. It must be ensured that, scale
should that distinctive features like roads,
buildings, canals etc. are properly traceble and
located on the sheet. For easy calculations
related to distance conversion, if the scale is
1cm =k m, then k m, then k should be selected
such that it is divisible by 5.

28

4.4. METHODS OF PLANE TABLING

The various methods are described below:
1.
Radiation: In this method, the plane table
is set up at only one station and points to be
plotted are located by radiating rays from the
instrument-station to the points and plotting to
scale the respective distances along rays.
2.
Intersection: In this method, the position
of the points are fixed on the sheet by the
intersection of the rays drawn from two
instrument- stations. The line joining these
stations is termed as base line. The only linear
measurement required in the method is that of
the base line. Tis method is largely employed
for locating outward details and for locating the
points to be used subsequently as instrumentstations. This may also be used for plotting
long distant and inaccessible objects, like river
electric poles etc. It is much suitable for
plotting objects or hilly country where it is
difficult to measure the lens horizontal
distances.
3.
Traversing: This is the main method of
plane tabling and is similar to that of compass
or theodolite traversing. It is used for running
survey lines of a closed or open traverse. The

29

detail may be located by offsets taken in the

usual manner or by the radiation or by
intersection method of plane tabling.
4.
Resection: This method is used for
locating
the
station
points
only.
The
characteristic feature of resection is that the
point plotted on the sheet is the stations
occupied by the table. After the stations are
fixed, surrounding details is located by
radiation or intersection.

5. CONTOURING
5.1. GENERAL INTRODUCTION
A contour or contour line is the imaginary line
connecting the points of equal elevation on the

30

ground and on the map it is the line joining these

points. If we trace contour line earths surface, it is
called contouring.
5.1.1. Contour Interval: The vertical distance
between two consecutive contours is called
contour interval. On survey camps contour interval
of 1m or 2m is generally taken.
5.1.2. Horizontal Equivalent: The horizontal
distance between two adjacent contours is called
horizontal equivalent. This distance is taken as 5 m
or 10m depending upon extent of area to be
surveyed.

5.2.
CHARACTERISTICS
CONTOURS
Characteristics of contour
(a) If the contour are widely
separated.
(b) If the contours are very
close to each other.
(c) If the contours are
parallel
and
equally
spaced.
(d) If the contours are
uniformly spaced.
(e) If the higher values of

Feature
Flat ground
Steep ground
Plane surface

Uniform slope
Depression

OF

31

(f)

(g)
(h)
(i)

(j)

(k)

contour are outside and

the contours are closed.
If the higher values of
contours are inside and
the contours are closed.
Loop in contours with
higher values outside.
Loop in contours with
higher values inside.
Contour lines cannot
merge over one another
except in one case.
If
several
contours
coincides and horizontal
equivalent c and the
contours.
Depression
between
summits.

Hill

Valley line
Ridge line
Over hanging cliff

Vertical cliff

Saddle

5.3. METHODS OF CONTOURING

1. Direct Method: This method is as follows:
First of all, we have to perform Fly- levelling or
Double- levelling from the nearest permanent
bench mark to establish a temporary bench mark
in the area. In Fly - levelling, we setup the
instrument in such a way that the observation on

32

maximum points is covered. In fly levelling,

instrument is shifted after each Fore sight reading
i.e. there are no intermediate sights in fly- leveling.
It is done for speedy work.
In Double levelling, two level men and one staff
man are involved. The method is the same as that
of Flylevelling but after every Back sight and Fore
sight reading, the difference of the above reading
taken with the two levels must be same. In such a
way, work is proceeded up to the highest point
from where radial contour lines are run.
3.Radial Line method: Draw the radial lines on
the ground at similar angle say 30 degree. If
the angle is less the accuracy is more. After
drawing the radial lines, fix the wooden pegs at
equal distance equal to the horizontal
equivalent. The distance can be adjusted if
some important feature is in between. After
this, fix the Dumpy level in such position so
that maximum readings of points are to be
covered from one setting. For speedy work in
hilly areas readings can also be taken by Abney
level or Ceylon ghat tracer. After this, contours
are interpolated.

33

5.4.
INTERPOLATION
CONTOURS

OF

It is the spacing of contours proportionally between

the plotted ground points. It is done by following
methods:
(a) By Estimation
(b) By Arithmetical Calculation
(a) By Estimation: It is the rough and speedy
method. In such a method, the position of
contour points between ground points are
estimated and then contour lines are drawn
through these points.
(b) By Arithmetical Calculation: It is an
accurate method and is used for important
works.
For example: Let X and Y be the two points on
the ground and their reduced levels are 39.35
and 42.65 respectively. The horizontal distance
between X and Y is 10m and contour interval is
1m. In between these two points, the three
contours which are located can be 40m, 41m,
42m.
Level difference between X and Y = 42.65-39.35
= 03.30m

34

Level difference between X and 40m contour

point= 40.00-39.35 = 00.65m
Distance of the 40m contour
(00.65/3.30)10m = 01.96m

from

Similarly, other distances are calculated.

5.5. EQUPMENTS
CONTOURING
(a) Auto level

USED

FOR

35

(b)Ranging rods

(c) Leveling staff

36

(d) Measuring tapes

(e) Arrows

(f) Wooden pegs

37

Reduced levels
point to hill top:Station
point

Back
sight

Intermedi
ate sight

Fore sight

from
rise

fall

Zero
Reduce
level

38
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
11.
12
13.
14
15.
16
17.
18.
19.
20.
21.
22.
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48

.715
.005
.255
.085
.175
.075
.01
.275
.145
.0265
.095
.155
.235
.365
.545
.02
.05
.29
.11
.095
.35
.12
.625
.415
.155
.395
.325.
.345
.165
.335
.305
.325
.510
.565
.685
.915
.555
1.775
.435
.230
.145
3.305
.635
.665
.320
.790
.870
.700

3.45
5.00
5.510
5.09
5.78
5.07
5.61
5.85
3.75
5.65
3.45
5.15
5.85
4.65
5.84
5.89
5.84
5.65
3.85
5.25
5.71
3.75
5.64
5.47
4.73
5.43
6.00
4.19
5.74
5.95
5.75
5.31
5.65
5.69
4.95
5.815
4.61
5.61
5.44
5.67
4.21
5.62
5.93
5.44
5.86
4.476
5.915

2.735
5.945
5.255
5.005
5.605
4.995
5.600
5.575
3.605
5.623
3.355
4.995
5.615
4.285
5.295
5.870
5.755
5.360
3.740
5.155
5.360
3.630
5.015
5.055
4.575
5.035
5.675
3.845
5.575
5.615
5.445
4.985
5.140
5.125
4.265
4.900
4.055
3.835
5.005
5.440
4.070
2.315
5.295
4.775
5.540
3.686
5.045

1000.00
997.265
991.32
986.065
981.06
975.455
970.46
964.86
959.285
955.68
950.057
946.702
941.707
936.092
931.807
926.512
920.642
914.887
909.527
905.787
900.632
895.272
891.642
886.627
881.572
876.997
871.962
866.287
862.442
856.867
851.252
845.807
840.822
835.682
830.557
826.292
821.392
817.337
813.502
808.497
803.057
798.987
796.672
791.377
786.602
781.062
777.376
772.331

39
49
50
51
52
53
54
55

.815
.445
.965
1.04
.735
.810

Station no

Back
sight
.460
1.465
1.185
1.2
1.68

56
57
58
59
Tree
42
Solar
point

no

3.77
4.64
5.925
4.375
5.80
5.63
1.395

Intermedi
ate sight

Fore sight

Rice

3.070
3.825
5.480
3.410
4.760
4.895
0.585
=253.69

769.261
765.436
759.956
756.546
751.786
746.891
746.306
=253.69

Fall

1.395
3.9
3.86
3.48
3.21

0.585
3.44
2.395
2.295
2.01

Reduce
level
746.306
742.866
740.471
738.176
736.166

1.77

0.09

736.076

=263.92
4

=263.92
4

40

Reduce level of trees

Tree no
42
43
44
46
47
48
49
50
51
52
53
54
56
57
58
59
60
Solar light
61
62
63
64
65
66
67
68
69
75
76
80
79
102
103c.p
106-105
Unknown
158
Hut
103
104
106
87
83

Back
sight
1.15

Intermedi
ate sight

Fore sight

.675
0.525
1.275
1.695
1.330
2.355
2.54
2.93
2.755
3.144
2.630
3.385
2.550
2.760
3.050
3.19
3.435
2.640
3.43
2.99
2.97
2.98
2.987
3.030
2.964
3.845
3.225
3.485
4.41
4.505
5.160
3.85

Rise

0.475
.15
.75
.42
0.365
1.025
.185
.39
0.175
0.389
0.514
.755
0.835
0.21
0.29
0.14
0.245
0.795
0.79
0.44
0.02
0.01
0.007
0.043
0.066
0.881
0.62
0.26
0.925
0.095
0.655
0.19
1.035
1.525
0.19

5.35
1.885
3.410
3.600
1.385

2.215

5.35
5.780
5.00
5.395

fall

0.19
0.43
0.78
0.395

Reduce
level
736.166
736.641
736.791
736.041
735.621
735.986
734.961
734.776
734.386
734.211
733.822
734.336
733.581
734.416
734.206
733.916
733.776
733.531
733.326
733.536
733.976
733.996
733.986
733.979
733.936
733.002
733.121
733.741
733.481
732.556
732.461
731.806
731.616
730.581
729.056
728.866
731.081
731.616
731.186
731.966
731.571

41
84
85
86
87
88
91
96
99
40
38
39
37
34
33
32
36c p
22
21
20
19
24
25
26-27
17-18
Brick
pillar
Solar light
16
14c p
13
12
Unknown
5
Unknown
4
3
2
1

4.775
4.605
4.905
4.605
4.735
4.690
5.145
5.81
.710
.800
1.690
.615
1.075
1.395
1.090
5.745

0.62
0.17
0.3
0.3
0.13
0.045
0.455
0.665
5.1
0.09
0.89
1.075
0.46
0.32
0.305
1.710

3.345
3.00
2.76
2.595
3.07
3.38
3.48
1.99
.94

0.475
0.31
0.10
1.49
1.05

1.29
1.03
2.725

0.35
0.26
1.295

2.79
2.175
1.58
1.46
1.94
0.555
.375
3.905

0.62
2.4
0.345
0.24
0.165

0.265
0.065
0.615
0.595
0.12
0.48

.110
3.335

1.385
0.18
0.265
0.57

732.191
732.361
732.061
731.761
731.631
731.586
731.131
730.466
735.566
735.476
734.586
735.611
735.201
734.881
735.186
734.566
736.966
737.311
737.551
737.716
737.241
736.931
736.831
738.321
739.371
739.021
739.281
739.016
738.951
739.566
740.161
740.281
739.801
741.186
741.366
741.631
742.201

42

Contour lines
Station no
Point E
Line -1
Point no 1
Point no 2
Point no 3
Point no 4
Point no 5
Point no 6
Line 2
Point no 1
Point no 2
Point no 3
Point no 4
Point no 5
Line no 3
Point no 1
Point no 2
Point no 3
Point no 4
Point no 5
Point no 6
Point no 7
Line no 4
Point no 1
Point no 2
Line no 5
Point no 1
Point no 2
Line no 6
Point no 1
Point no 2
Point no 3
Point no 4
Point no 5
Point no 6
Point no 7
Line no 7
Point no 1
Point no 2
Point no 3
Point no 4
Point no 5
Point no 6
Line no 8

Back sight

Intermedi
ate sight

Fore sight

Rise

fall

1.915
1.795
1.640
1.215
.905
.770
.960

0.12
0.155
0.425
0.31
0.135
0.19

1.920
1.830
1.890
1.895
2.26

0.96
0.09
0.06
0.005
0.365

1.980
2.020
2.03
2.57
2.905
1.310
1.340

0.28
0.04
0.01
0.54
0.335
1.595
0.03

1.545
1.080

1.155

0.6

736.311
736.656

0.54
0.02

736.116
736.096
736.116
736.116
735.991
735.841
735.911

0.02
0
0.125
0.15
0.07

2.020
2.185
2.265
2.425
2.575

0.06

2.575
1.77

736.011
735.971
735.961
735.421
735.086
736.681
736.651
736.446
736.911

0.345

1.875
1.895
1.875
1.875
2.000
2.150
2.080

736.071
736.161
736.101
736.096
735.731

0.205
0.465

1.680
1.335

Reduce
level
736.076
736.196
736.351
736.776
737.086
737.221
737.031

0.165
0.08
0.16
0.15
0

735.971
735.806
735.726
735.566
735.416
735.416
736.076

43
Point no 1
Point no 2
Point no 3
Point no 4
Point no 5
Point no 6
Point no 7
Point no 8
Point no 9
Point no
10
Point no
11
Line no 9
Point no 1
Point no 2
Point no 3
Point no 4
Point no 5
Point no 6
Line
no
10
Point no 1
Point no 2
Point no 3
Point no 4
Line
no
11
Point no 1
Point no 2
Point no 3
Line
no
12
Point no 1
Point no 2
Point no 3
Point no 4
Line
no
13
Point no 1
Point no 2
Point no 3
Point no 4
Point no
5
Line
no
14

1.345
1.495
1.615
1.890
2.780
2.765
3.050
3.280
3.22
3.38

0.19
0.15
0.12
0.275
0.89

0.16

735.886
735.736
735.616
735.341
734.451
734.466
734.181
733.951
734.011
733.851

0.04

733.811

1.18
0.32
0.3
0.18
0.055

735.861
734.681
734.361
734.061
733.881
733.831

1.485
0.13
0.37

735.831
734.346
734.216
733.846

1.12
0.41

735.501
734.381
733.971

1.475
0.325
0.135

735.856
734.381
734.056
733.921

1.48
0.215
0.27
0.065

735.936
734.456
734.241
733.971
733.906

0.015
0.285
0.23
0.06

3.42

1.370
2.550
2.870
3.170
3.350
3.405

2.05

1.400
2.885
3.015
3.385

2.005

1.73
2.85
3.26

1.655

1.375
2.85
3.175
3.31

1.885

1.295
2.775
2.99
3.26
3.325

2.015

44
Point no 1
Point no 2
Point no 3
Point no 4
Point no 5
Point no 6
Line
no
15
Point no 1
Point no 2
Point no 3
Point no 4
Line
no
16
Point no 1
Point no 2
Point no 3
Point no 4
Fencing
Point no 1
Point no 2
Fencing
Point no 1
Fencing
Point no
Point no
Point C
tree no 96
Line no 1
Point no 1
Point no 2
Point no 3
Line no 2
Point no 1
Point no 2
Line no 3
Point no 1
Point no 2
Point no 3
Point no 4
Line no 4
Point no1
Point no 2
Point no 3
Point no 4
Point no 5
Point no 6
Line no 5

1.265
2.46
2.91
3.09
3.22

2.06
1.195
0.45
0.18
0.13
3.24

2.535
1.140
.755
.350

0.02

1.41

736.521
737.916
738.301
738.706

2.155

736.551
737.976
738.221
738.751
736.076
737.506
738.516
736.076
733.436
736.076
733.336
733.896

1.395
0.385
0.405

2.505
1.080
.835
.305

1.425
0.245
0.53

1.565
.555

1.43
1.01

2.995
.5

1.77
3.140

2.64

1.155
1.895
1.335
.925

.74
.56
4.905

731.131

1.315
.925
.520

0.925
0.405

1.285
.0590

1.226

1.340
1.150
.870
.620

0.19
0.28
0.25

1.380
1.235
1.100
1.040
.935
.850

735.966
739.771
734.321
734.141
734.011
734.031

0.145
0.135
0.06
0.105
0.085

0.39

730.741
731.666
732.071

0.765

731.306
732.532

1.281

731.251
731.441
731.721
731.971

0.76

731.211
731.356
731.491
731.551
731.656
731.741

45
Point no 1
Point no 2
Point no 3
Point no 4
Point no 5
Point no 6
Line no 6
Point no 1
Point no 2
Point no 3
Line no 7
Point no 1
Point no 2
Point no 3
Point no 4
Line no 8
Point no 1
Point no 2
Point no 3
Point no 4
Point no 5
Point no 6
Point no 7
Line no 9
Point no 1
Point no 2
Point no 3
Point no 4
Point no 5
Point no 6
Point no 7
Point no 8
Point no 9
Point no
10
Point D
Tree
no
102
Line no1
Point no 1
Point no 2
Point no 3
Point no 4
Point no 5
Point no 6
Line no 2
Point no 1
Point no 2

1.375
1.320
1.280
1.255
1.280
1.380

0.525
0.055
0.04
0.025
0.025
0.1

1.350
.980
.655

0.03
0.37
0.325

1.385
1.185
.860
.555

0.2
0.325
0.305

1.535
1.450
1.305
1.085
.865
.660
.520

.975

731.241
731.611
731.936
0.73

731.206
731.406
731.731
732.036

0.98

731.056
731.141
731.286
731.506
731.726
731.931
732.071

1.605
0.07
0

730.466
730.396
730.396
730.426
730.491
731.101
731.256
731.451
731.621
731.781

0.085
0.145
0.22
0.22
0.205
0.14

2.125
2.195
2.195
2.165
2.100
1.490
1.335
1.140
.970
.810

0.03
0.065
0.61
0.155
0.195
0.17
0.16

5.160

731.806

1.20
1.305
1.44
1.50
1.615
1.650
1.220
1.310

731.216
731.271
731.311
731.336
731.311
731.211

0.225
0.105
0.135
0.006
0.115
0.035

731.581
731.476
731.341
731.335
731.220
731.185

0.09

731.615
731.525

0.43

46
Point no 3
Point no 4
Point no 5
Point no 6
Line no 3
Point no 1
Point no 2
Point no 3
Point no 4
Point no 5
Point no 6
Fencing
Line no 4
Point no 1
Point no 2
Point no 3
Point no 4
Point no 5
Point no 6
Point no 7
Point no 8
Fencing
Line no 5
Point no 1
Point no 2
Point no 3
Point no 4
Point no 5
Point no 6
Point no 7
Point no 8
Fencing
Line no 6
Point no 1
Point no 2
Point no 3
Point no 4
Point no 5
Line no 7
Point no 1
Point no 2
Point no 3
Fencing
Line no 8
Point no 1
Fencing
Line no 9
Point no 1

1.795
2.040
2.200
2.240

0.485
0.245
0.16
0.04

731.04
730.795
730.635
730.595

0.42
0.35
0.375
0.41
0.49
0.215

731.635
731.215
730.865
730.49
730.08
729.59
729.16

0.275
0.275
0.545
0.27
0.565
0.375
0.25
0.085

731.225
730.95
730.675
730.13
729.86
729.295
728.92
728.67
728.585

1.200
1.620
1.970
2.345
2.755
3.245
3.460

1.04

1.395
1.670
1.945
2.490
2.760
3.235
3.610
3.860
3.945

2.065

1.405
1.605
1.795
1.965
2.035
2.045
2.035
1.920

2.54

1.360
1.530
1.615
1.720
1.8

0.56

1.335
1.345
1.410
1.445

0.465

1.110
1.065

0.335
0.045

731.22
731.265

.975

0.63

731.895

0.2
0.19
0.17
0.07
0.01
0.01
0.1155

731.125
730.725
730.535
730.365
730.295
730.285
730.295
730.41

0.17
0.085
0.105
0.08

730.97
730.8
730.715
730.61
730.53

0.01
0.065
0.035

730.995
730.985
730.92
730.885

47
Fencing
Line
no
10
Point no 1
Point no2
Fencing
Line
no
11
Point no 1
Point no 2
Point no 3
Point no 4
Fencing
Line
no
12
Point no 1
Point no 2
Point no 3
Point no 4
Line
no
13
Point no 1
Point no 2
Point no 3
Point no 4
Line
no
14
Point no 1
Point no 2
Point no 3
Point no 4
Point no 5
Point no 6
Point G
Tank line
no
Point no 1
Point no 2
Point no 3
Point no 4
Point no 5
Point no 6
Point no 7
Point no 8
Line no 2
Point no 1
Point no 2
Point no 3

.900

0.075

.930
.705
.510

0.225
0.195

.630
.395
.195
.175

0.235
0.2
0.02

.940
.605
.350
.165

0.335
0.255
0.185

.945
.710
.440
.240

0.235
0.27
0.2

.945
.785
.630
.505
.260

0.16
0.155
0.125
0.245

1.675

731.97

0.03

731.94
732.165
732.36

0.12

732.24
732.475
732.675
732.695

0.765

731.93
732.265
732.49
732.675

0.78

731.895
732.13
732.4
732.6

0.705

731.895
732.055
732.21
732.335
732.58

1.395
2.355
2.225
1.785
1.355
2.205
1.140
1.105
1.2
2.390
2.220
2.075

746.306
0.68
0.13
0.44
0.43
0.85
1.065
0.035
0.095
1.19
0.17
0.145

745.626
745.756
746.196
746.626
745.776
746.841
746.876
746.781
745.591
745.761
745.906

48
Point no 4
Point no 5
Point no 6
Line no 3
Point no 1
Point no 2
Point no 3
Point no 4
Fencing
Line no 4
Point no 1
Point no 2
Point no 3
Line no 5
Point no 1
Point no 2
Point no 3
Point no 4
Point no 5
Point no 6
Point no 7
Point no 8
Line no 6
Point no 1
Point no 2
Point no 3
Line no 7
Tree no2
Point no1
Point no 2
Point no 3
Point no 4
Point no 5
Point no 6
Point no 7
Point no 8
Line no 8
Point no 1
Point no 2
Point no 3
Line no 9
Point no 1
Point no 2
Point no 3
Line
no
10
Point no 1
Point no 2

1.880
1.570
1.450

0.195
0.31
0.12

2.475
2.320
2.165
2.030
2.235

1.025
0.425
0.155
0.135
0.205

2.535
2.420
2.380

0.3
0.115
0.04

2.04
2.090
1.620
1.020
.690
.545
.630
.835

0.34
0.05
0.47
0.6
.33
.145
0.085
0.205

2.385
2.025
1.770
3.140

746.101
746.411
746.531

1.55

747.766
747.881
747.921
748.261
748.211
748.681
749.281
749.611
749.756
749.671
749.466

0.36
0.255

747.916
748.276
748.531

1.705
0.285
0.225
0.18
0.18
0.055
0.24
0

743.881
745.586
745.871
746.096
746.276
746.456
746.511
746.751
746.751

.110
1.435
1.15
.925
.745
.565
.510
.270
.270

747.556
747.981
748.136
748.271
748.066

1.71
1.770
-

1.44
0.06

745.331
745.251

1.875
2.280
2.890

0.105
0.405
0.61

745.146
744.741
744.131

1.920
2.035

745.101
744.986

49
Point no 3
Point no 4
Point no 5
Point no 6
Point no 7
Line
no
11
Point no 1
Point no 2
Point no 3
Point no 4
Line
no
12
Point no 1
Point no 2
Point no 3
Point no 4
Point A
Tree no 2
Line no 1
Point no 1
Point no 2
Point no 3
Point no 4
Point no 5
Point no 6
Point no 7
Point no8
Line no 2
Point no 1
Point no 2
Point no 3
Point no 4
Point no 5
Point no 6
Point no 7
Line no 3
Point no 1
Point no 2
Point no 3
Point no 4
Point no 5
Point no 6
Line no 4
Point no 1
Point no 2
Point no 3
Point no 4

3.135
2.995
3.190
3.62
3.970

743.886
744.026
743.831
743.659
743.051

1.935
2.470
3.350
3.890

2.035

1.935
2.4
3.145

1.955
3.50

0.470

0.535
0.88
0.54

745.086
744.551
743.611
743.131

0.460
.745
0.355

745.086
744.821
743.876
743.521

3.140
3.545
3.155
2.510
2.140
1.545
1.020
.705
.505

743.881
3.075
0.39
0.645
.37
0.595
0.525
0.315
0.2

740.806
741.196
741.841
742.211
742.606
743.331
743.646
743.846
741.191

3.160
2.465
2.020
1.470
1.000
0.475

0.695
0.445
0.55
0.47
0.525

3.435
3.210
2.535
2.365
1.910
1.370

0.225
0.675
0.17
0.455
0.54

3.650
3.180
2.655
-

2.655

0.47
0.525
-

741.886
742.331
742.881
743.351
743.876
2.96

740.916
741.141
741.816
741.986
742.441
742.981

2.28

740.701
741.171
741.696

50
Point no 5
Point no 6
Point no 7
Point no 8
Line no 5
Point no 1
Point no 2
Point no 3
Point no 4
Point no 5
Point no 6
Point no 7
Line no 6
Point no 1
Point no 2
Point no 3
Point no 4
Point no 5
Point no 6
Line no 7
Point no 1
Point no 2
Point no 3
Point no 4
Point no 5
Point no 6
Point no 7
Line no 8
Solar light
Point no 1
Point no 2
Point no 3
Point no 4
Point no 5
Point no 6
Point no 7
Point no 8
Point no 9
Line no 9
Point no 1
Point no 2
Point no 3
Line
no
10
Point no 1
Point no 2
Point no 3
Point no 4

1.740
1.785
1.170
.920

0.915
0.045
0.615
0.25

3.575
3.175
2.420
2.160
1.945
1.875

2.655

3.665
3.450
3.120
2.750
2.795
1.995

0.4

740.776
741.176

0.755
0.26
0.215
0.07

741.931
742.191
742.406
742.476
1.79

0.215
0.33
0.37
0.045
0.8

3.845
3.780
3.765
3.755
3.800
3.035

1.85

0.855

0.085

739.021
739.321
739.236

0.045
0.765
1.29

.905
.990
1.095
1.120
1.175
1.140
2.330
2.640

0.3

.980
1.105
1.200

1.66

1.065
1.480
3.325
3.245

0.135

0.105
0.025
0.055
1.19
0.31

739.131
739.106
739.051
739.086
737.896
737.586

0.415
1.845

739.246
739.121
739.026

0.035

0.415
1.845
0.08

740.686
740.901
741.231
741.601
741.556
742.356
740.506
740.571
740.586
740.596
740.551
741.316
740.461

0.065
0.015
0.01
3.890

1.205

742.611
742.566
743181
743.431

739.161
738.746
736.901
736.981

51
Line no11
Point no 1
Point no 2
Point no 3
Point no 4
Line no12
Point no 1
Point no 2
Line
no
13
Tree 27
Point no 1
Point no 2
Line
no
14
Point no 1
Point no 2
Line
no
15
Point no 1
Point no 2
Point no 3
Point no 4
Point no 5
Point no 6
Point no 7
Fencing
Line
no
16
Point no 1
Point no 2
Point no 3
Point no 4
Point no 5
Point no 6
Point no 7
Point no 8
Point no 9
Point no
10
Point no
11
Fencing
Line
no
17
Point no 1
Point no 2

1.650
3.300
3.460
3.500

1.595
1.65
0.16
0.04

.475

738.576
736.926
736.766
736.726

3.025
0.215

739.751
739.966

1.21
.435

736.931
738.141
737.76

0.33
0.25

737.376
737.126

0.195
1.14
0.56
1.75
0.1
0.095
0

737.286
737.091
735.951
735.391
733.641
733.541
733.446
733.446

0.15
0.735
1.06
0.23
1.63
0.1
0.155
0.29
0.145

737.251
737.101
736.366
735.306
735.076
733.446
733.346
733.191
732.901
732.756

5.495

0.11

732.646

5.590

0.095

732.551

0.415

737.366
736.951

.260

1.210

3.48
000
.435

.765
1.015

.855
1.050
2.190
2.750
4.50
4.600
4.695
4.695

0.16

.890
1.040
1.775
2.835
3.065
4.695
4.795
4.950
5.240
5.385

3.805

.775
1.190

4.815

52
Point no 3
Point no 4
Point no 5

1.3
2.760
3.155

0.11
1.46
0.395

736.841
735.381
734.986

PRACTICAL PROBLEMS IN SURVEY

CAMP
There are various problems which we face
during field work. Some of these are
described below:
1.
North
direction
without
any
instrument in field: Direct your hour hand
wrist watch towards sun. Then approximately
bisect the angle between the hour hand and 12
(figure) printed on the dial. This gives North
South line. If the direction towards the sun is
inclined at angles less than 90 degree, it is
south. If on other hand angle is greater than 90
degree, it is North.
2.
When the object to be sighted is too
high or too low in plane table surveying
(a) When the object is too high: In such case,
place the sharp pencil vertical at the center
of object vane and see at the bottom hole of
the sight vane, pointed tip of the sharp pencil

53

and the tip of the object all clearly visible,

and draw the radial line on the plane table
sheet. Shift the plane table to the next
station and doing the back sight orientation,
the same object is sighted followed by same
procedure and draw the radial line.
(b) When the object which is to be sighted
is too low: In this case place the sharp
pencil at the center of sight vane and see the
bottom hole of the object vane by leaning
forward, so that the line joining the top of the
pointed tip, bottom hole of the object vane
and the object all are clearly visible and draw
the radial line and then the above said
procedure is repeated after doing back sight
orientation on next station. Object is plotted
by intersection method. The above procedure
is adopted in case of plane alidade.
3.
Where the dumpy level is not properly
set up: Such problems arises where there will
be steep slope in elevation or in depression. In
this case use Abney level tied with the ranging
rod or Ceylon ghat tracer. Main precaution for
working on such instrument is, that their
position must be horizontal while taking the
readings. For making them horizontal, coincide

54

the zero of vernier with the zero division of the

main scale.
4.
When the leveling staff is too near the
instrument:In such case the graduation of the
staff are not visible. Then move up and down a
piece of white paper along the staff until the
edge of the paper is bisected by the line of
collimation. The reading is noted from the staff
with the naked eye. Sometimes readings are
taken by looking through the object glass i.e.
position of telescope is reversed.
5.
When the leveling staff is very far and
not clearly visible: In such case red colour
broad rubber band is used on it, i.e. the
visibility of red colour is maximum among all
the colours. The above procedure is repeated
i.e. instead of white paper, use the red broad
rubber band. The staff readings will not be
visible to the level man and the readings is
taken by staff man.
6.
When the objects on which the staff is
placed is too low: In such a case the leveling
staff is not visible through telescope of dumpy
level i.e. the line of collimation passes above
the staff. Then place the box of dumpy level on
the ground and place the staff over it. Suppose

55

the staff reading is XY and height of box PY is

measured with tape.
The total staff reading is (PY+XY)
When the object on which the staff is
placed is too high :When the staff is too high
then place the tie beam horizontally and held
the staff in the interval position and the
readings is then taken. Inverted staff readings
are entered with ve sign in the level book. If
such reading is back sight, -ve and if the same
is foresight then it is +ve.
How to fix the temporary bench mark
from fixed bench mark for contouring: In
such case either do fly leveling or double
leveling from the fixed bench mark up to the
point or place where it is required temporary
bench mark.