before going to viva you should know these points:
General principles of surveying are
 Working from whole to part: In this principle the whole area is first framed out
by main stations and survey lines. Then the area is divided into no. of wellconditioned
triangles and linear measurements are done which prevents in error
accumulation.
 Location of new control point by measurements from two control points: From
fixed reference points new stations are fixed from at least two measurements.
Measurements may be linear or angular (by chain, tape, theodolite, compass).

In a survey camp a single group has to conduct a detailed survey for
 Preparation of a topographic map of the given area
 Selection of a suitable Road alignment
 Selection of a suitable Bridge site
The general objectives of the survey camp are listed below-
 To become familiar with the surveying problems those are likely to arise during
the field works.
 To develop confidence in actual field surveying.
 To become familiar with different instruments, their functions and handling for
their use in surveying.
 To become familiar with the spirit and importance of teamwork, as surveying
cannot be carried out by a single person.
 To complete the task or the project within the given time limit.
 To collect the required field data in a systematic way.
 To compute and manipulate the observed data in the required accuracy and
present it in theoretical, tabular and diagrammatical forms that it is easily
understood by other engineering professionals.

SCOPE OF WORK FOR SURVEY CAMP

Topographic Map Presentation

Details
Area Coverage:1.5 to 2.0 hectares
Scale for the Plot of Major Traverse: 1:1000
Scale for the Plot of Minor Traverse: 1:500
Scale for Plot of Topographic Map: 1:500
Contour Interval:1 m (depending upon the site relief)
Control Points Establishment
• At least 25-35 stations (Main control stations)
• Two sets of Horizontal Angle, One set of Vertical Angle
• Distance measurement by three-way taping and by EDM (1:2000 accuracy)
• Vertical control by Leveling, check by trigonometric leveling
• Fly Leveling, at least 0.5 – 1.0 km (± 25√K mm accuracy)
• Leg ratio: Major Traverse 1:2, Minor Traverse 1:3

 Road Alignment Survey

•At least 500 m to 700m or more stretch
•Scale for Plan: 1:1000
•Scale for Longitudinal section: V – 1:100 & H – 1:1000
• Cross section: 20 m interval, scale same for V & H – 1: 100
•Left right observation: 10 m minimum on either side of proposed center line
Curve Setting
• Horizontal curve by both linear and angular method
• Vertical curve setting with gradient (7 to 12) %

 Bridge Site Survey

• up-stream details at least 120 m, Downstream details at least 40 m
• Scale for plotting minimum area of observation of coverage plan 1:500
• Contour interval: 2.0 m or depending upon the site relief
• Longitudinal section: H=1:200,V=1:100
• Cross section: (10 to 20) m interval (depending upon the site relief), scale
H=V=1:100

TOPOGRAPHICAL SURVEY

NORMS (TECHNICAL SPECIFICATIONS)

1. Reconnaissance survey of the area to be surveyed. Form a closed traverse (major

and minor) around the premises of the area by fixing or marking appropriate no.

of stations (11-15). In the selection of the traverse stations the leg ratio, i.e. the

ratio of length of the longest traverse leg to the length of the smallest leg, should

be less than or equal to 1:2 for major traverse and 1:3 for the minor traverse.

2. Two-way measurement of the traverse legs by means of a Total Station.

Accuracy of two-way measurement in the case of major traverse is 1:2000 and

1:1000 in the case of minor traverse. (Two-way measurement, i.e. measurement

of the traverse leg in the forward as well as in the backward direction.)

3. Two sets of angle measurement making use of a Total Station. The difference

between the mean angles as well as the difference in each angle observation

should be within 1′.

4. Determination of RL of traverse stations by fly leveling from the given BM.

Perform two peg test. Collimation error in the case of two peg test should be

less than 1:10000. Balancing of back sight and fore sight is necessary for the

elimination of different types of errors including collimation error. The

permissible error of fly leveling is ± 25√K mm, where K is the distance of the

leveling passed in kilometer.

5. Adjustment of traverse or balancing the traverse. The permissible angular error

or the angular misclosure for the sum of interior angles of the traverse should

be within C√N, where N denotes the no. of traverse leg or traverse stations and,

C=1’ for major traverse and C=1.5’ for minor traverse. For major traverse the

relative error of closure should be less than 1:2000 and that for minor should be

less than 1:1000.

6. Plotting of the traverse stations by co-ordinate method. An appropriate scale is

selected, i.e. 1:1000 for the traverse.

7. Detailing or the detail survey of the plot by Tachometric surveying. References

are drawn from the major and minor traverses. Conventional symbols are used

to denote the detailing along with the contours of 1 m contour interval in the

same scale

METHODOLOGY

The methodology is based on the principles of surveying. They are as follows:

1. Working from whole to a part

2. Location of a point with respect to at least two control points

3. Independent check

4. Consistency in work

5. Required accuracy

points which should be kept in mind for appropriate selection of major
traverse control points forming the closed traverse around the premises of the area to
be surveyed are summed up as follows:

1. The adjacent stations should be clearly intervisible.

2. The whole area should include the least number of stations possible.

3. The traverse station should maintain the ratio of minimum traverse leg to

maximum traverse leg less than 1:2 for major traverse and 1:3 for minor

traverse.

4. The stations should provide minimum level surface required for setting up the

instrument.

5. The steep slopes and badly broken ground should be avoided as far as possible

to avoid difficulties as well as reduction in accuracy in the measurement of the

traverse legs.

6. The station should not be selected such that the line of sight lies very much near

the ground level to avoid likely error due to atmospheric refraction.

points needed to be
kept in the mind while fixing major traverse stations are as follows:

 Inter-visibility of the adjacent major traverse stations.

 Maintaining of the permissible leg ratio of 1:2.

 Measurement of traverse legs without any obstruction.

 Fixing of stations with reference points as well as a neat sketch.

 Fixing of stations driving wooden pegs and marking with enamel and marker.

Measurement of traverse angles

The interior traverse angles were measured with the help of angle measuring instrument

or the electronic Theodolite. For achieving the internal traverse angle, 0º0’0″ was set at

the preceding station and the telescope was turned in the clockwise direction. In the

case of major traverse, two sets of angular measurement were observed having 0º0’0″

and 90º0’0″ set at the preceding stations. The angles obtained from these two sets were

averaged to get the mean traverse angle. The difference in two angles and as well in

each of the angular observation cannot exceed 1′ as stated earlier.

 Sum and the correction of the interior angles Permissible Angular Error for the

closed traverse = C√N

Where, N = no. of traverse legs

C=1’

For a closed traverse,

Sum of interior angles = (2n – 4) *90°

Closing error = (2n – 4) *90° – Σ Observed sum of internal angles

If the angular error is within the permissible value of 1′√N, then the error in the sum of

internal angles is equally distributed.

Bearing computation of the traverse legs

The bearing of the common line CP1-CP2 was observed with the help of a compass.

The bearing of the remaining traverse legs was computed. They were calculated using

following relation:

Bearing of successive line = Fore bearing of the previous line + clockwise traverse

angle ± 180° or 540°

Note:

1. If the sum of bearing and the traverse angle was greater than 180°, then

180° was subtracted from it, if the sum was less than 180°, the sum was

added to 180°, and if the sum exceeded 540°, 540° was subtracted from the

sum.

2. Bearings have been calculated in Whole circle system.

3. The closing error in the internal angles has been distributed equally to all

the angles prior to the computation of bearing of all the traverse legs.

Consecutive co-ordinates

The latitude of the survey line is defined as its coordinate length measured parallel to

an assumed meridian. It is also termed as northing.

The departure of the survey line is defined as its coordinate length measured

perpendicular to an assumed meridian. It is also termed as Easting.

Each station point is defined by its latitude and departure with respect to the origin.

Latitude of B, (y) = Latitude of A (Y) + L*cosθ

Departure of B, (x) = Departure of A(X) + L*sinθ

Where,

θ = Bearing of the line AB

L = Length of the line AB

In a closed traverse, the algebraic sum of the latitudes and departures must be zero if
linear as well as angular measurements of the traverse along with their computations
are correct. If not, the distance between the starting station & point or position of the
same station obtained by the calculation is known as closing error. 

A closed traverse can be balanced by any one of the following methods.

1. Bowditch’s method

2. Transit rule

3. Graphical method

4. Axis method

Bowditch’s method

errors in the linear measurement are proportional to √L and 

errors in the angular measurements are inversely proportional to √L where ‘L’ is the length of a line. The method is applicable when both

the linear as well as angular measurements are of equal precision.

The Bowditch rule is:

Correction to latitude (or departure) of any side

= Total error in latitude (or departure) * Length of that side

                                                                   Perimeter of traverse

Transit Method

the method is most applicable when angular measurements are of more precision than linear

measurement. According to this rule, the total error in latitude and in departure is

distributed in proportion to the latitude and departure of the sides. The angles are less

affected by the corrections applied by this method than by the Bowditch method.

The Transit rule is:

Correction in Latitude (or Departure) of any side

= Total error in Latitude (or Departure) * Latitude (or Departure) of that line

                                                                      Arithmetic sum of Latitudes (Departures)

Plotting of major traverse stations

After the computation and correction of the coordinates of the major traverse stations,

the traverse stations were plotted in the grid sheet. The entire grid should be checked

diagonally to avoid the plotting error. The major traverse stations were plotted in the

scale of 1:1000 to the grid paper. Paper management is done so that the drawn traverse

lies in the centre of the grid sheet which also comforts the detail drawing or the

preparation of the topographic map.

Leveling

Leveling is defined as the branch of surveying which deals in finding the elevations of

the given points with respect to a given or an assumed datum. It also deals with

establishing the points at a given elevation with respect to a given or an assumed datum.

It deals with the measurement in a vertical plane. It helps to provide the vertical controls

in a topographic map. The elevations of the relevant points must be known so that

complete topography of the area can be explored

1. Direct Leveling

a. Simple Leveling

b. Differential Leveling

c. Profile leveling

d. Cross- sectioning

e. Reciprocal leveling

2. Indirect leveling

Adjustment of level

i. Temporary adjustment of level

The adjustment of level that needs to be done before each observation is known as the

temporary adjustment of level. The temporary adjustment of the level is done in

following steps:

1. Setting up the level

The operation of setting up includes the fixing the instrument on the stand and leveling

the instrument approximately.

2. Leveling up

Accurate leveling is done with the help of foot screws and with reference to the plate

levels. The purpose of leveling is to make the vertical and horizontal line of sight truly

horizontal.

3. Removal of parallax

Parallax is a condition arising when the image formed by the objective not formed in

the plane of cross hairs. Parallax is eliminated by focusing the eyepiece for distinct

vision of the cross hairs and by focusing the objective to bring the image of the object

in the plane of the cross hairs.

ii. Permanent adjustment of level

Permanent adjustment of the level is the adjustment of level that is done when the

corresponding relationship between the parts of the instrument is disturbed.

Booking and reducing of levels

There are two methods of booking and reducing the elevation of points from the

observed staff readings. They are as follows:

a. HI Method

In this method, firstly the height of instrument is calculated by back sighting to a known

station i.e. adding back sight (BS) to RL of BM or previous known station for each

setting of instrument. The RL of the next station is then calculated by subtracting the

foresight (FS) to the HI. If any intermediate sights (IS) are taken, then their RL is also

calculated by subtracting IS from HI. HI is calculated for every new set up of

instrument.

b. Rise and Fall Method

It is the method which was mostly used in the survey camp for fly leveling as well as

in the case of transferring RL from TBM to the entire major and the minor traverse

stations. In rise and fall method, the height of instrument is not at all calculated but the

difference of level or elevation between consecutive points is found by comparing the

staff readings on the two points for the same setting of the instrument. The differencebetween their staff readings indicates a rise or fall according as the staff reading at the

point is smaller or greater than that at the preceding point. The figures for rise and fall

worked out thus for all the points give the vertical distance of each point above or below

the preceding one, and if the level of any one point is known the level of the next will

be obtained by adding its rise or subtracting its fall, as the case may be.

Arithmetic check

The difference between the sum of back sights and the sum of fore sights should be

equal to the difference between the sum of rise and the sum of fall and should be equal

to the difference between the RL of last and the first points. Thus,

ΣB.S. – ΣF.S. = ΣRise – ΣFall = Last R.L. – First R.L.

This provides a complete check on the intermediate sights also. The arithmetic check

would only fail in the unlikely, but possible, case of two more errors occurring in such

a manner as to balance each other.

Permissible Error and Correction

Permissible error in leveling is given by the relation Error = ±25√ where, k is the

distance in km.

Error is corrected in fly leveling by adding the half of correction in the calculated RL

of the end point.

steps followed while
carrying out the detail survey are summed up as follows:

 Instrument was set at each control point with accurate centering and leveling.

 The vertical distance from the center of the trunnion axis to the peg at the

ground was measured as the height of the instrument.

 The instrument was orientated with reference to a fixed station which is already

well defined.

 Target was held vertically as far as possible with proper leveling of the bubble

for the case detail survey and in the case of RL transfer from BM to major and

minor traverse stations the staff was held vertically as possible.

 Hard details were not missed as far as possible and were indicated by

numbering in the reference map for the future reference of plotting.

Contouring

A contour is an imaginary line of constant elevation on the ground surface. It is the line

in which the surface of the ground is intersected by the level surface.

Contour interval and Horizontal Equivalent

The vertical distance between any two consecutive contours is called the contour

interval. The contour interval is kept constant for a contour plan or the topographic

map; otherwise the general appearance of the map will be misleading. The horizontal

distance between two points on two consecutive contours is known as horizontal

equivalent and it depends upon the steepness of the ground. The choice of the proper

contour interval depends upon the following considerations:

 The nature of the ground

 The scale of the map

 The purpose and the extent of the survey

 Time and expense of field and the office work

Characteristics of Contours

The characteristic features of the contour which are used while plotting and reading a

contour map or the topographic map are summed up as follows:

1. Two contour lines of different elevations cannot cross each other. They can cross

each other only in the case of overhanging cliff.

2. Two contour lines of different elevations cannot unite to form a single. If they do,

it is only in the case of vertical cliff.

3. Closely spaced contour lines represent a steep slope. Broadly spaced contour lines

represent a gentle slope. Equally spaced contour lines represent a uniform slope.

A series of straight, parallel and equally space contours represent a plane surface.

4. A contour line cannot split into two or more contour lines.

5. A series of closed contour lines with higher value of contour i.e. with contour

having higher value of elevation inside represent a hill where as a series of closed

contour lines with lower value of contour inside represent a pond or the depressed

land.

6. A contour line must close upon itself, though not necessary within the limits of the

map.

7. Contour lines cross a watershed or the ridge line at right angles. They form curves

of U-shaped round it with the concave side of the curve towards the higher ground.

8. Contour lines cross a valley line at right angles. They form sharp curves of Vshaped

across it with the convex side of the curve towards the higher ground.

9. The same contour appears on the either side of a ridge or valley, for the highest

horizontal plane that intersects the ridge line must cut it on the both the sides. The

same is true of the lower horizontal plane that cuts a valley.

Interpolation of the Contour lines

Interpolation of the contour is the process of spacing the contours proportionately

between the plotted ground points established by indirect methods. The method of

interpolation is based on the assumption that the slope of the ground between the two

points, which are surveyed, is uniform. There are different methods of interpolation of

contours. They are as follows:

i. By estimation

ii. By arithmetic calculations

iii. By graphical method

By Estimation

This method is extremely rough and is used for small scale work only. The position of

the contour points between the guide points are located by estimation.

By Arithmetic Calculations

The method, though accurate, is time consuming. The position of contour points

between the guide points are located by arithmetic calculation.

X= (H/V)*Y

Where, X= Horizontal distance of the point to be located H= Horizontal distance

between two guide points V= Vertical distance between two guide points

Y= Vertical distance between the point to be located and lower elevation point

By Graphical Method

In the graphical method, the interpolation is done with the help of a tracing paper or a

tracing cloth.

BRIDGE SITE SURVEY

The objectives of the bridge site survey can

be summed as follows:

 To find the best location for a bridge over the river considering the factors like

convenience, economy and geological stability.

 To determine the physical properties of the river such as discharge, velocity of water,

bed slope etc.

 To exercise the reciprocal leveling for RL transfer in bridge axis.

 To perform triangulation method for measuring the bridge axis and detailing 120m

upstream and 60 m downstream.

 To prepare topographic map of the bridge site and hence prepare longitudinal and crosssections

of the river at the required upstream and downstream of the river.

 To accumulate the past information about the high flood level, normal flow level, river

cut direction, river shifting pattern etc.

NORMS (TECHNICAL SPECIFICATIONS)

1. Control point fixing as well as determining the length of the bridge axis had to be

accomplished by the method of triangulation. While forming the triangles, proper care

had to be taken such that the triangles were well conditioned i.e. none of angles of

triangles were greater than 120° or less than 30°.

2. The triangulation angles were to be measured by two sets of reading and the difference

between the mean angles of two sets was to be within 1’.

3. RL was transferred from the BM to stations by the method of fly leveling and then to

the stations on another bank of the river by the method of reciprocal leveling.

4. The scale of the plotting topographic map was 1:500. The contours were drawn in an

interval of 1m.

5. In order to plot the longitudinal section of the river, detailing had to be done 150m

upstream and 75m downstream. The plot for the longitudinal section along the flow line

had to be in a scale of 1:50 for vertical and 1:500 for horizontal.

6. For the cross section profile data was taken at 20m intervals both upstream and

downstream, and one at the bridge axis. Observations had to cover minimally 20m

across the bank of the river on the either side. The scale of the cross sections was 1:100

for both vertical and horizontal.

The following things were considered while selecting a bridge site:

1. The rocky outcrops were studied and as they were strong enough to support the bridge

and the dead as well as the live loads the site was concluded to be suitable.

2. The slope of the riverbed was to be gentle at the proposed site because steep slope means

the greater magnitude of the water current, a lot of erosion and wear and tear takes place

on the bridge foundation. Hence to avoid that condition, location of the bridge was

chosen at the place where there was less current.

3. The high flood level of the river was measured accurately and hence the height of the

river above the river was designed taking into consideration the occasional flooding.

4. The bridge was chosen at such a place that it is very convenient to approach. Hence its

use is predicted to be huge thus providing service to a large number of the local people.

Besides, the stones and the coarse aggregates could also be used from local sources nearby

reducing the transportation cost.

Triangulation

Triangulation is the process of forming number of connecting triangles so as to provide the

control points. Triangulation involves two processes, measurement of horizontal distances of any

two side of the triangle formed on the opposite side of the frame between two control points by

tape and the measurement of all the interior angles with the help of angle measuring instrument

i.e. Theodolite. All the remaining lengths of the sides of the triangle are computed with the help

of any one measured length and all the measured angles of the triangles formed. The axis length

of the proposed bridge was computed as mentioned earlier using sine law in the triangles.

Reciprocal Leveling

When it is necessary to carry out leveling across a river, ravine or any obstacle requiring a long

sight between two points so situated that no place for level can be found from which the lengths

of foresight and back sight will be even approximately equal, special method, i.e. reciprocal

leveling must be used to obtain accuracy and to eliminate the error in instrument adjustment,

combined effect of earth’s curvature and the refraction of the atmosphere and the variation in the

average refraction.

ROAD ALIGNMENT

OBJECTIVES

Road alignment survey was done to accomplish the following objectives:

1. To determine the natural and physical properties of the soil to be used in the

embankment.

2. To facilitate the design of the slopes of the embankment and cuts.

3. To determine the construction techniques for handling the earthwork.

4. To classify the earthwork (ordinary soil, hard soil, soft rock, hard rock etc.) to

estimation of cost and planning for the blasting operation and other excavation

techniques.

5. To design the pavement thickness and specifications.

NORMS (TECHNICAL SPECIFICATIONS)

1. Simple horizontal curves had to be set out where the road changed its direction,

determining and pegging three points on the curve- the beginning of the curve,

the middle of curve and the end of the curve along the centerline of the road.

2. The radius of the curve had to be chosen such that it was convenient and safe,

i.e. not less than 12m.

3. The gradient of the road had to be maintained at 12%.

4. Cross sections had to be taken at the interval of 20m including the beginning,

middle and end of the curve, along the centerline of the road – observations

being taken for at least 10m on either side of the centerline. If undulations are

present, then sections at such places is a must.

5. Plan of the road had to be prepared in a scale of 1:1000.

6. L-section of the road had to be prepared on a scale of 1:1000 horizontally and

1:100 vertically.

7. The cross-section of the road had to be prepared in a scale of 1:100(both

horizontal and vertical).

8. The amount of the cutting and filling required for the road construction had to

be determined from the L-section and the cross-sections. However, the volume

of cutting had to be roughly equal to the volume of filling.

Note: If the external deflection angle at the I.P. of the road is less than 3°, curves need

not to be fitted.

METHODOLOGY

For the selection of the alignment for hill roads following points are considered.

1. The route should be selected to attain the changes in the elevation by the

adoption of ruling gradient according to type of road in most of the length.

2. Deep cuttings and fillings should be avoided as far as possible.

3. Areas prone to landslides and settlement and having unstable hill features

should be avoided in the alignment.

4. Steep terrain should be avoided as far as possible.

5. The alignment should be preferable lying on the side of the hill exposed to sun

in winter.

6. Before selecting the alignment in hillsides, saddles, valleys, crossing points of

major river etc. examined in detail first.

7. Hair-pin bends should be avoided as far as possible. But when they become

unavoidable, they should locate in the gentle and slopes. Gentle slopes reduce

the cost of retaining walls.

8. Needless rise and fall should be avoided.

9. The alignment should crass the ridges at the lowest elevation.

Deflection angle (Δ) = (360° or 180°) – Observed angle.

Simple Circular Curve

A simple circular curve is the one which consists of a single arc of a circle. It is

tangential to both of the straight lines namely tangents. During the road survey, it is

always kept in mind that the radius of the simple circular curve should not be less than

11m. As far as possible, flat circular curves are preferred to that of the sharp one. Flat

curves are comfortable to the passengers and there is less possibility of accident. Before

setting out the curve, its elements are essential to be computed. Some essential elements

of simple circular curve are as follows:

Length of tangent: R tan (Δ/2)Where, R = radius of simple circular curve Δ = deflection angleLength of long chord: 2R sin(Δ/2)Apex distance: R (sec(Δ/2) – 1)Mid ordinate: R (1 – cos(Δ/2))Length of curve: πRΔ                              180°Chainage of T1: Chainage of IP – R tan (Δ/2)Chainage of T2: Chainage of T1 + πRΔ                                                           180°

Super-elevation

When a pavement or a track is sloped upwards the outside of the curve, it is termed as

banked or super elevated. Thus, ‘super-elevation or cant’ is the amount by which the

outer end of the road or outer rail is raised above the inner one.

The length of transition curve should be such that the required super-elevation or cant

is provided at a suitable rate. There are three methods for determining its length:

1. By an Arbitrary Gradient

2. By the Tim Rate

3. By the Rate of Change of Radial Acceleration
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