Viva Questions Surveying

Department of Civil Engineering

SHRI MADHWA VADIRAJA INSTITUTE OF TECHNOLOGY & MANAGEMENT

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10CVL38/10CVL47 Surveying Practice I/II Laboratory: Viva Questions & Answers

1/13

CHAIN SURVEYING

1. What is the fundamental difference between surveying and leveling?

In surveying the measurements are taken in horizontal plane, but in leveling they are

taken in the vertical plane.

2. What is the fundamental difference between plane surveying and geodetic surveying?

In Plane surveying, the curvature of the earth is not considered. But in Geodetic

surveying, the curvature of the earth is considered.

3. What do you mean by terms topographical map and cadastral map?

A map which shows the natural features of a country such as rivers, hills, roads, railways,

villages, towns, etc. is known as topographical map, and one which shows the boundaries

of estates, fields, houses, etc. is known as a cadastral map.

4. What is the main principle of surveying?

The fundamental principle of surveying is to work from the whole to the part.

5. How is a chain folded and unfolded?

In order to fold the chain, a chainman moves forward by pulling the chain at the middle

so that two halves come side by side. Then he places the pair of links on his left hand with

his right hand until the two brass handles appear at the top.

To unfold the chain: A chain man holds the two brass handles in his left hand and throws

the bunch with his right hand. Then one chain man stands at a station holding one handle

and another chainman moves forward by holding the other handle.

6. In a chaining operation, who is the leader and who is the follower?

The chain man at the forward end of the chain who drags the chain is known as the

leader and the one at the rear end of the chain is known as the follower.

7. While chaining a line, if you have to measure through a steep sloping ground, what

method should you apply?

The stepping method.

8. Two stations are not intervisible due to intervening high ground. How will you range the

line?

The ranging is to be done by the reciprocal method.

9. What do you mean by normal tension?

The tension at which the measured distance is equal to the correct distance (i.e; when

sag correction is neutralized by pull correction) is known as normal tension.



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2/13

10. What do you mean by RF?

The ratio of the distance on the drawing to the corresponding actual length of the object

is known as RF.

11. What is the difference between plain scale and diagonal scale?

The plain scale represents two successive units. The diagonal scale represents three

successive units.

12. What is hypotenuse allowance?

When one chain length is measured on slopping ground then it shows a shorter distance

on the horizontal distance is known as the hypotenusal allowance.

13. How many ranging rods are required to range a line?

At least three ranging rods required for direct ranging and at least four for indirect

ranging.

14. What is the length of one link in a 20m chain?

The 20m chain is divided in to 100 links. So, one link is 0.2m. i.e; 20cm. long.

15. What is the Principle of chain surveying?

The Principle of chain surveying is triangulation.

16. What do you mean by triangulation?

The method of dividing an area into a number of triangles is known as triangulation.

17. Why is the triangle preferred to the quadrilateral?

The triangle is preferred just it is a simple figure which can be drawn by just knowing the

lengths of its sides.

18. What is the disadvantage of using ill conditioned triangles?

The apex point of an ill conditioned triangle is not well defined and sharp. This may cause

some confusion while marking the actual point correctly on the map.

19. What is reconnaissance survey?

The preliminary inspection of the area to be surveyed is known as reconnaissance survey.

20. What is an index sketch?

During reconnaissance survey a neat hand sketch is prepared showing the frame work of

the survey. This sketch is known as index sketch.



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3/13

21. What is base line of survey?

Base line is the back bone of the survey. The frame work of the survey is prepared on this

line.

22. How is the north line of the chain survey map fixed?

The north line of the chain survey map is fixed by taking the magnetic bearings of the

base line by prismatic compass.

23. Suppose you are asked to conduct a chain survey in a crowded town what would you say?

In chain survey, whole area is to be divided into a number of triangles. But the formation

of triangles is not possible in a crowded area. So I would reject the proposal.

24. What should be the maximum length of the offset?

The maximum length of the offset should be within the length of the tape used.

Generally it should not be more than 15m.

25. How is a station marked on the ground?

The station is marked on the ground by a wooden peg and with a cross on the station

point.

26. What is the need of a reference sketch?

If the station peg is removed by some one the station can be located accurately with the

help of measurements shown in reference sketch.

27. How will you set up a perpendicular with the help of only a chain and tape?

By forming triangle in the ratio 3:4:5 using the chain and tape.

28. Who are the leader and follower when a line is being chained?

The chain man at the forward end of the chain who drags the chain is known as the

leader. The one at the rear end of the chain is known as the follower.

29. Why does the field book open lengthwise?

If the field book is opened lengthwise, it becomes easy to maintain the continuation of a

chain line.

30. Why is the scale always drawn in the map?

The paper on which the map is drawn may shrink or expand due to various reasons. If the

scale is plotted on the map, then it is also reduced or enlarged proportionately. So the

distance on the map measured by this scale remains unaltered.

31. What is it necessary to provide tallies in a chain?



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4/13

Tallies are provided in a chain for the facility to counting some fractional length of the

chain, when the full chain length is not required.

32. What do you mean by the term ideal triangle?

An equilateral triangle is said to be ideal.



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5/13

COMPASS SURVEYING

1. What is the principle of compass surveying?

The principle of compass surveying is traversing, which means that the area is enclosed

by series of connected lines .The magnetic bearings of these lines are taken with the

compass and the distances of sides of measured by chain.

2. What difference between triangulation and traversing?

Triangulation involves dividing an area into a number well conditioned triangle. But

traversing involves the consideration of a series of connected lines.

3. What does the term chain angle mean?

When the angle between two adjacent sides is fixed by chain and tape only by taking tie

line, the angle is said to be chain angle.

4. What is a 12 cm compass?

The size of compass is designated by its diameter. Therefore a 12cm compass is a

compass of diameter 12cm.

5. What is the fundamental difference between the prismatic compass and the surveyors

compass?

The prismatic compass shows the whole circle bearing of a line, whereas the surveyors

compass shows the quadrantal bearing of a line

6. How would you detect the presence of local attraction in an area?

When fore bearing and BB of alien differ by exactly 180 then the line is free from local

attraction. The presence of local attraction is established when the FB and BB do not

differ by 180.

7. The FB of a line 96 30' and BB is 276 0' how will you adjust the bearings?

Here, FB of line is 96 30' and so BB is of this line =96 30'+1800'=27630'

But the observed bearing is 2760'. So the adjusted BB =1/2(27630'+2760')=27615' and

adjusted FB=27615'-1800'=9615'

8. What is local attraction?

The disturbing influence of magnetic substances on a magnetic needle is known as local

attraction.

9. What is declination?

The horizontal angle between true meridian and magnetic meridian is known as

declination.



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6/13

10. What are isotonic and agonic lines?

The line passing through points of equal declination is known as isogonic line and the one

passing through points of zero declination is called the agonic line.

11. What do you mean by azimuth?

The true bearing of a line is known as its azimuth.

12. The FB of a line is 14530', what is its BB?

BB of line = 14530'+1800'=32530'

13. The FB of a line is S 4530'W, what is its BB?

BB of the line =N 4530' E

14. What are the precautions to be taken while shifting a prismatic compass from one station

to another?

The sight vane must be folded.

15. A compass was properly balanced at the equator. What will be the effect on the needle if

it is taken to northern hemisphere?

The north end of the needle will be inclined towards the North Pole.

16. What is angular check of a closed traverse?

The sum of the interior angles should equal to (2n-4) X90, where n is the number of

sides traverse.

17. How would you check the accuracy of open traverse?

The accuracy of open traverse is checked by taking cut-off lines or an auxiliary point.



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7/13

PLANE TABLE SURVEYING

1. What is the principle of plane tabling?

The principle of plain tabling is parallelism, meaning that the plain table is always placed

in every station parallel to the position it occupied at the first station.

2. What is orientation? Why is it done?

The method of keeping the table in successive stations parallel to the position it occupied

at the starting station is known as orientation.

Orientation is done to maintain, perfectly the relative positions of different objects on

the map.

3. How are centering and leveling done in plane tabling?

The centering is done by U-fork and plumb bob. The upper pointed end of the U-fork is

kept in contact with the station-pin when the plumb bob is just over the station peg.

Leveling is done by spirit level .The spirit level is placed at the different corners and at

various positions on the table. By adjusting the legs of the table, the bubble is brought to

the centre.

4. What are the methods of plane tabling?

The methods of plane tabling are radiation, intersection, traversing and resection.

5. When would u apply resection?

To establish a new station with the help of two points or stations.

6. What is intersection? When it is required?

The method of locating an object by the intersection of rays drawn from two stations is

called the intersection method. This method is applied for locating inaccessible points,

that is, when it is not possible to measure the distance from the station to the object.

7. When would you apply the two point and three point problem?

If it is found after completion of plane table survey that an important object has not been

plotted, then the two point or three point problem is applied to locate a new station.

These problems can be applied even if all the station pegs have been removed.

8. What do the terms great triangle and great circle mean?

In the three point problem, the triangle formed by joining three well defined points is

known as the great triangle and the circle passing through them is called the great circle.

9. One month after the completion of a plane table survey, it was detected that one

important object was not plotted. How will you plot the object on going to the field?



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8/13

A new station has to be established with the help of two point or three point problem.

The object can then be located with reference to that new station.

10. What type of orientation would you prefer and why?

Orientation by back sighting is always preferred, because it is more reliable than the

magnetic needle method. In this method, magnetic substances do not affect the work.

11. What method would you apply for locating inaccessible points?

The method of intersection should be applied in order to locate inaccessible points.

12. What do you mean by the fiducial edge of the alidade?

The working beveled edge of the alidade is known as fiducial edge.

13. What are the different types of the alidade?

There are two types of alidade - plain and telescopic.

14. What do you mean by strength of fix?

In the three point problem, the relative positions of A, B, C and the required

point P should be such that the required point can be located very quickly and accurately.

The accuracy with which the point can be fixed is termed as the strength of fix.

15. What are the precautions you have to take while centering the alidade with the station

pin?

The alidade should be centered on the same side of the station pin throughout the

traverse. Keeping the alidade on the left of the station pin is ideal.



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9/13

CONTOURING

1. What is a contour line?

A line joining points of equal elevation is known as contour line. .

2. Define the terms contour interval and horizontal equivalent?

The vertical distance between two consecutive contours is called contour interval. The

horizontal distance between two consecutive contours is known as horizontal equivalent.

3. Why is the horizontal equivalent not constant?

The horizontal distance between points varies according to the variation of slope. As the

slope of the ground between two consecutive contours is not constant in all directions,

the horizontal equivalent is constant.

4. In some places consecutive contours run close together and in some places they are wide

apart. What does this mean?

Contours running close together indicate a steep slope. When they run wide apart, it

indicates a flatter slope.

5. How will you distinguish between a depression and a summit by studying the nature of

the contour?

In case there is a depression, the contours run close together near the bank (outside) and

wide apart at the centre. In the case of a summit, the contours run close together near

the peak (centre) and wide apart at the base (outside)

6. In a map, it is found that two consecutive contours cross each other. What would you

comment?

In general, contour lines cannot cross each other, except in the case of an overhanging

cliff. Therefore, the area represented in the map includes an overhanging cliff. But the

contour line should be dotted line at the point of crossing to indicate that one location is

below the other.

7. How will you distinguish between a valley line and a ridge line?

When the lower values are inside the loop, it indicates a valley line. When the higher

values are inside the loop, it indicates a ridge line.

8. What is a contour gradient?

In a hilly area, the centre line of a road in a given gradient is marked by some points. The

line joining such points is known as contour gradient.

9. What is the object of preparing a contour map?

From a contour map, the nature of the ground surface of an area can be known. So, for

identifying a suitable site for a dam or reservoir and for marking the tentative alignment

of engineering projects involving roads, railways, etc, a contour map is essential.



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10/13

VOLUME COMPUTATION

1. State the trapezoidal rule. What are the considerations and limitations of this rule?

To the sum of first and the last ordinate, twice the sum of the intermediate ordinates is

added. This total sum is multiplied by the common distance and half of this product is the

required area. This is the trapezoidal rule. The boundaries between the ends of ordinates

are assumed to be straight lines. There is no limitation in this rule It can be applied at any

number of ordinates.

2. State Simpsons rule. What are the considerations and limitations of this rule.

To the sum of the first and the last ordinate, four times the sum of even ordinate and

twice the sum of odd ordinate are added. This total sum is multiplied by the common

distance. One third of this product is the required area. This is Simpsons rule.

The boundary between the ordinates is assumed to form an arc of a parabola. To apply

this rule .The number of ordinates must be odd.

3. What is a planimeter?

It is an instrument for measuring the area of a field from the map.

4. What is a zero circle?

When a circle is described by the tracing point without a change in reading in the

measuring wheel, then that circle is known as zero circle.

5. Give the simplest method for finding the area of a zero circle from the manufacturer

table.

Area of zero circle =M X C, where M= Multiplier and C =Constant. The value of both M &

C are available in the table.

6. What is the need of finding the area of the zero circle?

When the anchor point is inside the figure, the computed area does not cover the whole

area. It is less by the area of the zero circle .In that case the area of the zero circle is

added to the computed area to obtain the actual area.



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11/13

LEVELLING

1. What is a datum surface?

A datum surface is an arbitrarily assumed level surface from which the vertical distances

of various objects are measured.

2. What does the term GTS mean?

GTS Means Great Trignometrical survey

3. What are bench marks?

A reference point whose RL is fixed with respect to the datum surface is Known as bench

mark.

4. What is the datum adopted for GTS bench mark?

The mean sea level at Karachi is adopted as the datum for GTS bench marks. It is

considered as zero.

5. What are the types of bench mark that you know of?

Four types i) GTS B.M ii) Permanent BM iii) Temporary B.M iv) Arbitrary BM

6. For any engineering work, how will you get the RL of the starting point?

The starting point is connected to the GTS or permanent BM by fly leveling. Then the RL

of the starting point is calculated by the usual method.

7. What is the difference between a level surface and horizontal surface?

A surface parallel to the mean spheroidal surface of the earth is known as a level surface.

But a horizontal surface is tangential to the level surface at any point.

o The surface of a still lake is considered to be level.

o The Surface perpendicular to the direction of gravity (indicated by the plumb

line is considered to be horizontal.

8. What is the difference between the line of collimation and axis of the telescope?

The line of collimation is the line joining the point of intersection of the cross-hairs to the

optical centre of the object glass.

The axis of the telescope is the line joining the optical centre of the object glass to that of

eye piece.

9. What is the relation between the line of collimation and the axis of a telescope?

Both these line should coincide.



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12/13

10. In a particular set up of the level, suppose four reading are taken. How should they be

entered in the level book?

The first reading should be entered in the B.S column, the last reading in the FS column,

and the other two readings in IS column.

11. What is a change point?

Such a point indicates shifting of the instrument. At this point, a foresight reading is taken

from one setting and a back sight reading from the next setting.

12. The staff readings on A & B are 1.735m and 0.965m respectively. Which point is higher?

Point B is higher.

13. What is the procedure of levelling by foot screws?

The Telescope is first placed parallel to any pair of foot screws and the bubble is brought

to the center by turning the foot screws equally either inward or outward. Then the

telescope is turned through 90 and the bubble is brought to the center by turning the

third foot screw. This process is repeated several times until the bubble remains in the

center of its run.

14. How the levelling is centered?

In a leveling operation, the level is never centered. It can be set up at any suitable

positions. The level is centered only when the magnetic bearing of any line is taken with

the compass attached to the leveling instrument.

15. Suppose a level is given to you whose line of collimation is not in adjustment. What is the

procedure that you would follow in order to work with this instrument?

The principle of equalizing back sight and four sight distances should be followed. This

means that the level should always be placed exactly mid way between BS and FS.

16. How will you continue levelling across a river?

Reciprocal levelling should be undertaken across a river.

17. How will you continue levelling across a lake or pond?

We know that the water surface of a lake or pond is level. So two pegs are fixed on

opposite banks flush with the water surface. Then an FS reading is taken on the one peg

and RL is calculated. After this a BS reading is taken on the other peg. As the water

surface is level, the RL of the second peg is assumed to be equal to that of the first peg,

and the leveling operation is continued.

18. What are the arithmetical checks for the HI method and the rise & Fall method?

The arithmetical check for the HI method is as follows.



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13/13

BS-FS= Last RL-First RL

The arithmetical check for the rise and fall method is

BS-FS = Rise-Fall= Last RL-First RL

19. What is fly leveling?

The leveling operation in which only BS and FS readings are taken and no intermediate

sights are observed is known as fly leveling .Fly leveling is done for connecting the BM to

the starting point of any project. In such leveling no horizontal distances are required to

be measured.

20. What is check leveling?

In case of Longitudinal leveling ,at the end of the days work The finishing point is

connected to the starting point of that days work by fly leveling , to check the accuracy

of the work .This operation is called check leveling.

21. What is a Temporary BM?

In case of longitudinal leveling .at the end of the days work a bench mark is kept at

some suitable point. This BM is called a temporary bench mark.

22. Why is Datum assumed for plotting a leveling operation?

The RL of any point can not be plotted to the full scale showing its full elevation. So, a

datum (a reference line of assumed RL) is suitably assumed to show only the undulation

of the ground surface.

23. What is the difference between temporary and permanent adjustment?

Temporary adjustment is done at every set up of the instrument before taking staff

readings. Permanent adjustment is done in order to rectify any disturbed relationships

between the fundamental lines.

24. What would you mean by positive RL and negative RL?

The vertical distance of a point above the datum surface is known as positive RL. The

vertical distance of a point below the datum surface is known as negative RL.

25. How would you measure the distance between two points with only a level and staff?

The distance can be measured by the stadia method. The difference of the stadia hair

readings is multiplied by 100 (stadia constant) to get the required distance

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Viva Questions Surveying

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