Surveying Practice r2

8/22/2019 Surveying Practice r2

1/46

Sri Adichunchanagiri Shikshana trust

SJB Institute of TechnologyBGS Health & Education City, Kengeri, Bangalore-560060

Laboratory Manual

SURVEYING PRACTICEI

Sub Code: 10CVL38

(As per VTU Syllabus)

Department of Civil Engineering


2/46

SURVEYING PRACTICEI

Sub Code: 10 CVL 38

Table of Contents

List of exercises ............................................................................................................. 1Introduction to instruments in chain surveying. ........................................................... 3Exercise-1 ...................................................................................................................... 6Exercise-2 .................................................................................................................... 12Exercise-3 .................................................................................................................... 13Exercise -4 ................................................................................................................... 19Exercise- 5 ................................................................................................................... 20Exercise-6 .................................................................................................................... 21Exercise-7 .................................................................................................................... 26Exercise-8 .................................................................................................................... 28Exercise-9 .................................................................................................................... 31Exercise-10 .................................................................................................................. 33Exercise-11 .................................................................................................................. 35MINOR INSTRUMENTS .......................................................................................... 39VIVA QUESTIONS .................................................................................................... 41


3/46

3rd Semester: Surveying -1 Lab Manual

Dept of Civil Engg SJBIT, Bangalore Page 1

SURVEYING PRACTICEI

Sub Code: 10 CVL 38

List of exercises

Exercise1

a) To measure distance between two points using direct ranging

b) To set out perpendiculars at various points on given line using cross staff, optical square

and tape.

Exercise2

Setting out of rectangle, hexagon using tape/chain and other accessories

Exercise3

Measurement of bearing of the sides of a closed traverse & adjustment of closing error by

Bowdich method and Transit method

Exercise4

To set out rectangles, pentagon, hexagon, using tape /chain and compass.

Exercise5

To determine the distance between two inaccessible points using chain/tape & compass.

Exercise6

To locate points using radiation and intersection method of plane tabling

Exercise7

To solve 3-point problem in plane tabling using Bessels graphical solution

Exercise8

To determine difference in elevation between two points using fly leveling

technique & to conduct fly back leveling. Booking of levels using both HI and Rise & Fall

methods.

Exercise9


4/46



To determine difference in elevation between two points using reciprocal leveling and to

determine the collimation error

Exercise10

To conduct profile leveling for water supply /sewage line and to draw the longitudinal

section to determine the depth of cut and depth of filling for a given formation level.

Demonstration

Minor instrumentsClinometer, Ceylon ghat tracer, Hand level, Box sextant.


5/46



Introduction to instruments in chain surveying.

1. Study of chains and its accessories

Chain Surveying Description of the Instrument

a) Chain:

1. The chains are made in length of 30m and 20m2. Brass tullies are fixed at every 5m length.3. Small brass rings are provided at every 1m length.4. This is composed of 100 to 150 pieces of galvanized mild steel wire 4mm in

diameter called links.

5. The ends of each links in 20 cm i.e. the distance between the two consecutive middlerings.

6. The length of the chain is measured from the outside of one handle to the other.7. The ends of the chains are provided with brass handles for dragging the chain in the

ground.

8. The length of each links are bent into a loop connected together by means of threeoval rings which give flexibility to the chain.

9. To fold the arrows in position with the handle of the chain a .. is cut on theoutside surface of the handle.

b) Ranging Rod:

1. They are usually of 2m or 3m in length.2. They are in circular cross section and having alternate black, white and red bands of

20cm in length each to make them visible at a distance.

3. They are used for ranging the lines and for marking the position of the points onground.


6/46



c) Arrows:

1. They are made up of a wire 4mm diameter for 40cm length.2.

They are pointed at one end for inserting into the ground and bent at the other end

for facility of carrying.

3. They are used for mark the end of each chain during chaining.

d) Offset Rods:

1. They are used for measuring rough offsets.2. They are rounded rods with pointed end on one side and provided with notch or anook at the other end to facilitate the pulling, the pushing the chain through obstructions.


7/46



e) Cross Staff:

1. It consists of a wooden block with two fine row cuts at right angles to each other onthe top.2. It is used to set a perpendicular at a given point on the chain line.3. This head is fixed to a top of an iron staff with pointed end to derive into the ground.

f) Optical Square:

1. This is also used to set a perpendicular with more accuracy.2. This has two mirrors placed at angle of 45 to each other.3. By means of reflection we can see the ranging rods along the chain line and theoffset point at right angles to the chain line simultaneously.

Result:


8/46



Exercise-1

a) To measure distance between two points using chaining and ranging of a lineAim: To find out the distance between two points using chain. Instruments Required:

Chain

Arrows

Ranging rods

Procedure:

The two end points A and B are selected on a survey line which is to be measured. A

ranging rod is erected at the point B, while the surveyor stands with another rod at point A.

A rod is established at a point in line with AB at a distance not greater than one chain length

from A. The surveyor at A then signals the assistant to move transverse to the chain line till

he is line with A and B. Similarly other intermediate points can be established. Then by

using chain, the distance is measured. In carrying out fieldwork code signals are used .

Result:

The distance between two points ____________


9/46



b) To Set out perpendiculars at various points on given line

Aim: To set out perpendiculars at various points on given line using cross staff, opticalsquare and tape.

Apparatus Required:

Chain

Tape

Arrows

Ranging rods

Cross staff

Optical square

Theory: There are several types of instruments used to set out a right angle to a chain line.

The most common being cross staff, optical square and tape.

The simplest instrument used for setting out angle is a cross staff. It consists of either a

frame or box with two parts of vertical slits and is mounted on a pole for fixing in the

ground. The most common forms of cross staff are open cross staff, French cross staff,

adjustable cross staff.

.

Cross Staff


10/46



Optical square: It is more accurate and convenient instrument for finding foot of the

perpendicular or to set a right angle. It is a metal box of 50mm dia. And 120 mm deep.

There three openings such as pin hole, a small rectangular slot and a large rectangular slot

To set a right angle on a survey line, the instrument is held on the line with its centre on the

point at which perpendicular is erected. The slits F&G are directed towards the ranging rod

fixed at the end of the line. The surveyor rod and stationing in a direction roughly

perpendicular to the chain line, to move till the two images described above coincide.

O tical s uare


11/46



a) Perpendiculars setting using tape.Procedure:

The method of establishing perpendicular with the tape are based on familiar geometricconstruction. The following are some of the methods most commonly used. The

illustrations given are for a 10 m tape. 20 m tape the chain ages are plotted in a sheet and

the area is calculated by taking approximate scale.

i) 3-4-5 method:

Let it be required to erect a perpendicular from the chain line at a point C in it. Establish a

point at a distance of 3m from C. With zero end of the tape measure 4m & 5m to D and Erespectively. The point D established will be at right angles to the chain lines.

ii) Second method:

Select convenient length of the tape held at two points on the chain line. Stretch the middle

of the tape length. Stretched position of middle point locates the point D which is CD

perpendicular to chain line.

iii) Third method:

Select a point F,FC as radius and F as centre draw an arc to locate E extend EF to D such

that FD=EF.


12/46



Perpendiculars setting using tape

b) To drop a perpendicular to a chain line from outside point:

Let it be required to drop to a perpendicular to chain AB from a point D outside it.

i) First method: Select any point D outside the chain line AB.a perpendicular distance of

DC is swung over chain line AB.

ii) Second method: Select any point the on the line join CD and bisect it at F. with F as

centre & CF or FD as radius draw an arc to cut the chain line at C, CD will be

perpendicular to the chain line.

iii)Third method:Select a point E near foot of perpendicular on line AB. Locate the mid-

point F of ED. Then F as centre swing a tape length equal to FE to locate C

c) Perpendicular setting using optical square:

To set a right angle on a survey line, the instrument is held on the line with its centre on the

point at which perpendicular is erected. The slits F&G are directed towards the ranging rod

fixed at the end of the line. The surveyor rod and stationing in a direction roughly

perpendicular to the chain line, to move till the two images described above coincide.


13/46



d) Perpendicular setting using cross staff:

1. The cross staff is setup at a point on the line where perpendicular is to be set out.2. The cross staff is turned until one line of sight bisects the ranging rod at the end of

the survey line.

3. The line of sight through the other slit will be at right angle to the survey line andranging rod maybe established in that direction.


14/46



Exercise-2

Setting out of geometrical figures by linear measurements

Aim: To set out rectangle, hexagon using chain/ tape.

Apparatus Required:

Chain, Tape, Arrows and Ranging rods

PROCEDURE:

a) To set out a rectangle

1. Let it be required to set a rectangle ABCD OF 10m x 5m2. Measure a distance AB of 10m.3. Erect perpendiculars of 5m length at A & B using cross staff4. Join CD and check the distance which should be 10m.

b) To construct a rectangular hexagon of x m side.

1) Draw a circle of x m radius.2) Cut the circumference in to arcs of x m length.3) Join the consecutive points and the hexagon is obtained.


15/46



Exercise-3

Compass traversing

Aim: To measurement of bearing of the sides of a closed traverse & adjustment of closing

error by Bowditch method and Transit method.

Apparatus required:

1.Prismatic compass

2.Tripod

3.Ranging rod

4.Tape

5.Pegs & hammer

Theory:

There are two types of compasses:

1) Prismatic compass

2) Surveyors compass.

Prismatic Compass:

Prismatic compass is very valuable instrument. It is usually used for rough survey for

measuring bearing and survey lines. The least count of prismatic compass is 30 min. It

consists of circular box of 10cm-12 cm dia. of non magnetic material. Pivot is fixed at the

centre of box and is made up of hard steel with a Sharp pivot. Graduated aluminum is

attached to the needle. It is graduated in clockwise direction from 0 to 360 .the figures are

written in inverted. Zero Is written at south end and 180 at north end and 270 at the east.

Diametrically opposite are fixed to the box. The sighting vane consists of a hinged metal

frame in the centre of which is stretched a vertical Horse hair fine silk thread of which is

stretched a vertical hair. It presses against a lifting pin which lifts the needle of the pivot

and holds it against the glass lid. Thus preventing the wear of the pivot point to damp the

oscillations of the needle when about to take reading and to bring to rest quickly, a light


16/46



spring is brought lifted inside the box. The face of the prism can be folded out the edge of

the box when North end is used Sometime the sighting vanes is provided with a hinge

mirror Which can be placed upward or downwards on the frame and can be also Slidedalong it is required. The mirror can be made inclined at any angle so that Objects which are

too high or too low can be sighted directly by reflecting.

Adjustment of the Prismatic Compass:

The compass may be held in hand but for better results it should be fitted at the top of tripod

having ball and socket arrangement. The adjustment of a compass is done in the following

three steps.

1) Centering: The compass fitted over the tripod is lifted bodily and placedapproximately on the station peg by spreading the leg of a tripod equally, the centre

of the compass is checked by dropping a small piece of stone from the centre of the

bottom of the compass so that it falls on the top of the station peg. A plumb bob may

be used to judge the centering either but attaching it with a hook providing at the

bottom or otherwise by holding it by hand.

2) Leveling: After the compass is centered, it is leveled by means of ball and soketarrangement so that the graduated circle may swing freely. It can be checked roughly

by placing a round pencil on the top of the compass, when the pencil does not move,

that is roughly the horizontal position.

3) Focusing the Prism: The prism attached is moved up and down so that graduationon the graduated circle should become sharp and clear.


17/46



Surveyors compass:

The object vane is similar to that of prismatic compass. The eye vane consists of a simple

metal vane with fine silt without the prism. The graduated ring is directly attached to the

box and not to the needle. The object should be signed first with the object and eye vane

and reading is then taken against the north end by looking vertically to the top glass.

Bowditch's Method: To balance a traverse where linear and angular measurements are

required this rule is used and it is also called as compass rule. The total error in latitude and

departure is distributed in proportion to the lengths of the sides.

The Bowditch's rule is:

Correction to latitude (or departure) of any side =

Total error in latitude (or departure) * length of that side /perimeter of traverse

Thus if, CL= correction of latitude of any side

CD= correction to departure of any side

L= total error in latitude


18/46



D= total error in departure

l= length of the perimeter

l= length of any side

CL=L*(l/l) and CD=D*(l/l)

2) Transit Method: It is employed when angular measurements are more precise than

linear measurements.

The Transit rule is: Correction to latitude (or departure) of any side =

Total error in latitude (or departure) * latitude L(or departure D) of that lineArithmetic sum of latitude LT(or departure

DT)

CL=L*(L/LT) and CD=D*(D/DT)

3) Graphical Method: Bowditch's rule may be applied graphically without doingtheoritical calculation. It is not necessary to calculate latitudes and departures.

However before plotting the traverse directly from the field notes the angles or

bearings may be adjusted to satisfy geometric conditions of the traverse.

Problem: Calculate the latitudes, departure and closing error for the traverse usingbowditch's rule.

Line Length R.B Latitude Departure

AB 89.31 N 450 10' E 62.97 63.34

BC 219.76 N 720 05' E 67.61 209.1

CD 151.18 S 180 08' E -143.67 47.05

DE 159.1 S 480 43' W -104.97 -119.56

EA 232.26 N 590 18' W 118.58 -199.71

Sum 0.52 0.52


19/46



Closing error, e = (0.52)2 +(0.22)2 = 0.565 m

= tan-1 (0.22/0.52) = 220 55' 56''

Toatal correction for latitude = -0.52 , Total correction for departure = -0.22

l = Perimeter of traverse = 89.31+219.76+151.18+159.1+232.26 = 851.61

Correction for latitude, CL=L*(l/l) = 0.52* l/851.61 = -6.106*10-4 l

Correction for departure, CD=D*(l/l) = 0.2* l/851.61 = -23485*10-4 l

Line Latitude

Latitude Correction

Corr. Lat

Departure

Departure Correction

Corr. Dept

AB 62.97 -0.05 62.92 63.34 -0.02 63.32

BC 67.61 -0.13 67.48 209.1 -0.06 209.04

CD -143.67 -0.09 -143.76 47.05 -0.04 47.01

DE -104.97 -0.1 -105.07 -119.56 -0.04 -119.6

EA 118.58 -0.15 118.43 -199.71 -0.06 -199.77

Sum -0.52 0 -0.22 0

Procedure:

1) Let A,B,C,D,E,F are the traversing stations.2) Set the compass sat station A and take the FB of the line AB.3) Measure the distance AB.4)Now shift the instruments to the B take the bearing of the line BC.5) Take the back bearing of line AB.6) Measure the distance BC.7) Thus the length and bearing of each line of the traverse is to be measured.8) Adjustment of traverse error is done as per Bowditch and Transit method.


20/46



Observations and Calculation

Line Length R.B Latitude Departure

AB

BC

CD

DE

EA

Sum


21/46



Exercise -4

Constructions of regular geometrical figures using compass.

Aim: To set out rectangle, pentagon, hexagon using compass

Instruments required: Prismatic compass, tripod, ranging rods, arrows and tape

Calculations: Included angle for a regular polygon is given by IA=((2n-4)/ n)x90

Where n=no of sides

FB of a line =BB of previous line-IA.

Procedure:

1. The FB for the various sides of the regular geometrical figure are calculated.2. The compass ois set up at the first station & is centered.3. The bearing of the first line is set out & the next station is located by measuring the

distance in that direction.4. The instrument is shifted to the next station& the FB for the next line is set out. The

next station is located by measuring the distance along that direction.

5. The procedure is repeated for all the lines.


22/46



Exercise- 5

Distance between Inaccessible stations using compass

Observations:

When the instrument is at p

Bearing of the line PA=

Bearing of the line PB=

Bearing of the line PQ=

When the instrument is at Q

Bearing of the line QP=

Bearing of the line QA=

Bearing of the line QB=

Distance PQ= D=

Calculation:

Procedure:

1. Let it be required to determine the distance between two inaccessible stations A & B.

2. Select a line PQ approximately parallel to AB.

3. Set the compass at P, & Take the bearing of the line PA, PB & PQ

4. Now shift the instrument to station Q. Level it. Now take the FB of the line QP, QA &

QB.

5. Measure the distance PQ.

The distance AB is computed, by applying sine & cos rules for the triangles.


23/46



Exercise-6

Plane table surveying-radiation method and intersection method

Aim: To locate the points by the method of radiation and intersection

Apparatus required:

1)Plane table with tripod

2)Plumbing fork

3)Alidade

4)Trough compass

5)Spirit level

6)Pegs & hammer

7)Ranging rods

Theory: Plane table surveying and description of the instrument

The system of surveying in which field observation and plotting work i.e. both are done

simultaneously is called plane table surveying.

Plane Table:

The drawing board made of well seasoned wood such as teak or pine which is used for the

purpose of plotting is called plane table. It is available in sizes 500x400x15mm,

600x5000x15mm and 750x600x20mm.The top surface of board is perfectly plane and to

the underneath it is fitted with a leveling head or ball and socket arrangement. The table is

mounted on a tripod by means of a central screw with a wing nut or in such a manner so

that the board can be revolved, leveled and clamped in any position.


24/46



Alidade: The tool or instrument which consists of metal (usually of brass) or wooden (well

seasoned) rule 40cm to 60cm long, 3cmto5cm wide and fitted with two vanes at the ends is

called an alidade.

Trough Compass: The compass which is used to mark the direction of the magnetic

meridian on the plane table is called trough compass.

Plumbing Fork or U-frame: The plumbing fork to which is attached a plumb bob ,used

for centering the plane table over the station occupied by the plane table it is also meant for

transforming the ground point on to sheet so that both the points should be in the same

vertical line.


25/46



Radiation Method:

When from a single set of plane table on instrument station different details are located on

the sheet, the method is known as radiation method In this method the rays are drawn from

the instrument station to the point to be located, then the distances are measured from the

instruments station to the point and the position of the each point is plotted on the sheet

using a suitable scale. The method is most suited for surveying small areas which can be

controlled by single setting. It can also be used in combination with other method. This

method can be applied for locating distant points if the distances are obtained

tacheometrically with the help of the telescope alidade.


26/46



Procedure:

Select the position of the table where it is be set so that all the points to be located are

visible from it. Let O be the position of such a point on the ground.1) Set the plane table over this point and level it. Draw the North line in the top corner

of sheet by means of trough compass at the table.

2)Now transfer the position of the point O on the ground to the sheet by means of thea plumbing fork. The point O will represent point o will represent point Oon the

ground.

3) With the alidade touching the point o( may be represented by fixing a pin), sightthe point A in the field. Draw the ray along the fiducial edge. Measure the distance

of this point from the instrument station by means of tape and plot the point a

corresponding to point A in the field to scale in the sheet.

4) Similarly sight other points such as B, C, D, E etc. and measure their distances fromthe instrument station. Plot them to scale to get their position on the sheet such as b,

c, d etc. on the sheet.

Result:

The distance between the points A, B and C, D by the method of radiation are


27/46



Intersection method

Procedure:

1. The table is setup at 0 and leveled the point 0 is transferred from the ground to thesheet by plumbing fork and the table is clamped.

2. With the help of the trough compass, the north direction is marked on the sheet.3. Pivoting the alidade about 0, A is sighted. The distance 0,A is measured and plotted

along with the ray to get a. The base line 0,a is thus drawn.

4. Pivoting the alidade about 0, the points B,C,D etc., are sighted and correspondingrays are drawn.

5. The table is shifted to 0 and set up at 0. The table is roughly oriented by compassand finally by back sighting A.

6. Pivoting the alidade about 0,B,C,D etc., are sighted and the corresponding rays aredrawn, to intersect with the previously drawn rays in b,c,d etc., The positions of the

points are thus mapped by the way of intersection.

Result:

The distance between the points A, B and C, D by the method of intersection are

_______m.


28/46



Exercise-7

Graphical method

Two graphical methods are available to solve threepoint problem. They are

a) Bessels solution

b) Method of perpendiculars

Bessels solution:

In this method

1. Keep fiducially edge alo g ba andn sight object at A. clamp the table. Pivotingalidade at b sight C and draw line bc

2. Keep fiducial edge of alidade along ab. Unclamp0 the table and sight B. clamp thetable. Pivoting alidade at a sight station C and draw lien to intersect

3. Keep the fuducial edge of alidade along dc and bisect C. clamp the table this givesthe correct orientation of the table.

4. Let resector Aa intersect cd at P this is the plotted position of station P. this may bechecked with resector Bb.


29/46



Method of perpendiculars:

The steps involved in solving three point problem are:1. Draw ae perpendicular to ab. Keep alidade along ea and turn the table till A is

sighted. Clamp the table and draw the ray Bb to intersect the ray Aae at e.

2. Similarly, draw cf perpendicular to bc. Clamp the table when fcC are in a line. DrawBb to intersect Ccf at f.

3. Join df. Drop bp perpendicular to ef P is the plotted position of instrument station P.4. Orient the table such that pbB are in a line. Clamp the table. This is the required

orientation. Check the orientation by drawing resectors Aa and Cc.


30/46



Exercise-8

Study of levels and leveling staff

Aim: To study about the types of levels and leveling staff.

Description of the Instruments:

The Level:

The instrument which is used for measuring related elevations is known as a level and

consists of the following parts.

1. A telescope to provide a line of sight.2. A level tube to make the line of sight horizontal.3. A leveling head to bring the rubber of the level tube at the centre of its run.4. A tripod head to support the above three parts of the level.

Types of Level:

Dumpy Level:

1. This consists of a telescope rigidly fixed to its supports.2. It can neither be rotated about its longitudinal axis nor it can be removed from the

support.

Wye Level:

1. The telescope is supported in y-support ant its rigidly fixed to the supports.2. The telescope can be removed from the supports reversed end to end can be removed

about in longitudinal axis.

Reversible Level:

1. The telescope can be rotated about its longitudinal axis in the sockets and also can bewith drawn from its sockets and replaced end for end.

Tilting Level:

1 The telescope can be tilted within a few degrees is vertical plane by a tilting screen.


31/46



2 This is designed for precise work.Telescope Leveling Staff:

1. It consists of three pieces; top piece is solid 1.25m long where as central. Piece1.25m is below.

2. When fully extended total length of the staff is 4m.3. Each meter is subdivided into 200 divisions. The thickness of the graduations

being 5mm.

4. Spacing indicating the diameter readings is marked in red while all other spacesare marked in black against white background.

5. The diameter markings are continuous throughout the staff.6. The graduations are inverted so that, through telescope, they appear correct.

Temporary adjustments of dumpy

level: Setting up the level:

1This included fixing the instrument the tripod and leveling the instrument approximately

by leg adjustment.

2To do this release the clamp hold the instrument right and fix it on a tripod by turning


32/46



round the leveling head with left hand.

3The tripod legs are adjusted so that the telescope is at a convenient height and is leveled

approximately.Leveling Up:

1. This is done with the help of three foot screws and by using plate levels.2. The object of leveling is to make its vertical axis truly vertical.3. First loosen the clamp screw and then the instrument until the longitudinal axis of the

bubble tube is parallel tube to the line joining any to leveling screws.

4. Holding the two foot screws with the thumb and first finger of each hand moveseither towards each other or away from each other until the bubble comes to the

center.

5. Rotate the upper plate through 50 until the axis of the plate level coincide a linejoining the third foot screw c and the midpoint of the first two screw A and B.

6. Hold the third screw with thumb and fore finger of the hand and turn it will platebubble is central. Rotate the upper plate through 90 to its original position.

7. Rotate again through 90 and step 6 is repeated.8. Steps 4 and 6 are repeated until the bubbles remain central in both the position.9. The instrument is rotated through 180 and in this position the bubble should remain

central if the instrument is adjusted.

Elimination of parallax:

1. Parallax is a condition a rising when a image formed by objective is not in planecross hairs.

2. To get accurate sighting this should be eliminated and this is done by3. Focusing the eyepiece for distinct vision of cross hairs.4. Focusing the objective to bring the image of the objective in the plane of cross hairs.

Result:


33/46



Exercise-9

Fly leveling

Aim: To find the R.L of various points of the R.L of the B.M is given by 100m.

Apparatus Required:

1. Dumpy level

2. Tripod

3. Leveling staff

Procedure:

1.The instrument is placed in a point there by we can easily sight B.M. The following

initial adjustments are made.

a) The instrument is fixed in tripod stand and it is leveled approximately by legadjustment.

b) The clamp is loosened and the instrument is turned until the longitudinal axis of theplane level is parallel to the line joining only two leveling screws.

c) The foot screws are uniformly turned such that it means either inward or outwardsuch that the bubble is at the center.

d) The plate level is located and made parallel to line joining the third foot screw andmid point of the first two foot screws.

e) The third screw is adjusted to make the bubble central.f) The instrument is rotated through 180 to check whether the bubble remains central

after rotation the eye piece is adjusted to avoid parallax error.

2.The staff is kept at a given bench mark and readings is noted in back sight column.

3.In the same instrument station, another change point is shifted and reading is noted as

fore sight.

4.Then the same instrument is shifted to another station. Similarly back sight is taken. Thus


34/46



the procedure is repeated by changing the point and instrument station from the reading

taken R.L of point can be found.

Observation:

Tabulation

Back Sight (m) Inter Sight (m) Fore Sight (m) Reduced

Level

Height

Collimation

B.S ~ F.S = F.R.L ~ L.R.L

Result: Thus R.L of the points was found out by using fly leveling=


35/46



Exercise-10

Check levelling

Aim: To check the given reduced level of the starting point using Dumpy level.

Apparatus required:

1. Tilting level2. Tripod3. Leveling

Procedure:

1. The instrument is placed at a point there by we can sight B.M2. The temporary adjustments are done.3. The instrument is leveled by eye adjustment and by adjusting tripod legs.4. Then parallax error is eliminated.5. The staff is kept at a given BM and the readings are noted as Back sight.6. In the same instrument station other points are sighted and the readings are noted as

inter sight except the last which is fore sight.

7. The instrument is shifted to another station and the readings are taken.8. The process is repeated to come back to the starting point to check the given R.L of

the given starting point.

9. Then by any of the two methods (ie) by height of collimation method by rise and fallmethod then the required values are calculated.


36/46



Tabulation:

Result: Thus the given R.L of the starting point is checked using dumpy level by check

leveling.


37/46



Exercise-11

Longitudinal section and cross section

Aim: NL-Section and cross section of the road

Apparatus required:

1.Dumpy level

2.Leveling staff,

3.Ranging rod,

4.Tape

Theory: Profile Leveling

The process of determining elevations at points at short measured intervals along a fixed

line is called Longitudinal or profile leveling.

Cross Sectioning:

It is a method of leveling to know the nature of Ground on either side of the centerline of

the proposed route. Levels are taken at right angles to the proposed Direction of the road

end at suitable distances and leveling is carried out along this cross Section.

During location and construction of highways, Rail tracks sewers and canals strakes or

other marks are placed at various aligned points and the undulation of the ground surface

along a predetermined line is adjoined. The line of section may be single straight lines

changing directions.

Levels are taken at right angles to the proposed Direction of the road end at suitable

distances and leveling is carried out along this cross section. Cross section are the sections

run at right Angles to the centerline and on the either side of it for the purpose They are

taken at each 10,m station on the centerline. The length of Cross section depends upon the

nature of the work if cross sections are Short they are set square out by edge. If long they

are set out by the Optical square, box sextant or theodolite. They are serially numbered

from the beginning of the Centerline and are taken simultaneously with the longitudinal


38/46



section they may be taken at the hand level, level, abney level or theodolite.

Procedure:Let ABC be the line of section set out on the ground and marked with pegs driven at equal

interval (say 20m to 30m) as in the figure. The level is set up generally on one side of the

profile to avoid too short sight on the points near the instrument and care is taken to set up

the level approximately midway between two change points. The leveling is started from

the bench mark of known value. From each set up staff reading are taken on pegs already

fixed at the desired interval and also at significant points where about changes of slope etc.

occur.

All these readings are recorded as intermediate slight against the respective chain ages

along the line in the level book. Other data of the level book is also filled up before starting

the work. When the length of sight is beyond the power of the telescope (usually it is

100m), the foresight on the change point is taken. The level is then is then shifted and setup

in an advanced position and a back sight is taken on the change point. The change point

may or may not lie in the line of section. Chaining and reading are then continued as before,

till the whole line of section is completed. The work is to be checked in the progress of

leveling by taking reading on other bench marks, on the way or on bench marks fixed by

differential leveling. The fore and back bearing of the section line should betake and

recorded.

Next sketches of the bench mark, change points, and other feature such as nallah, a road,

canal, etc. crossing the section line be drawn and fully described in the remarks column ofthe level-book.

The procedure and corresponding reading and values are represented on the page of a level-

book for a part of road project.


39/46



Plotting The Longitudinal Section:


40/46



Level Book:

Whenever leveling operation is carried out the staff reading taken in the field is

entered in the note book called a Level-Book. Each page of it has the following

columns which help in booking of reading and reduction of levels.

Result:


41/46



MINOR INSTRUMENTS

AIM: To study the use of following minor instruments

1. Clinometers2. Ceylon Ghat Tracer3. Hand Level4. Box Sextant5. Planimeter6. Pantagraph.

CLINOMETER: Clinometers are used for the measurement of slopes, tracing

contours, setting grades, to determine the difference in elevation. There are various

types of clinometers.

1. Abney clinometers (Abney Level)2. Indian pattern clinometers3. Delisles clinometers4. Foot rule clinometers.

CEYLON GHAT TRACER: It is very useful instrument for setting out gradients. It

essentially consists of a long circular tube having a peephole at one end and cross

wires at the other ends. The tube is supported by a frame having a hole at top to fix the

instrument to a straight rod or stand. The tube is also engraved to live readings of

gradients with heavy weight slides along the tube by a suitable rack and pinionarrangement. The weight, at its top, contains one beveled edge which slides along the

graduations of the bar, and serves as a index. He line joining the hole to the

intersection of the cross wires and its prolongation defines the line of sights. When the

beveled edge of the weight is against the zero readings, the line of sight is horizontal.

For the elevated gradients, the weight is slides towards the observer. For falling

gradients the weight is slides away from the observer.


42/46



HAND LEVEL: It is a simple compact instrument used for reconnaissance and

preliminary survey for locating contours on the ground and for taking short cross

sections.

BOX SEXTANT: It is a small pocket instrument used for measuring horizontal and

vertical angles.

PLANIMETER: It is a device used to measure the area of an irregular boundary

figure.

PANTAGRAPH: It is an instrument used for reproducing, enlarging or reducing the

maps. It is based on the principle of similar triangles.


43/46



VIVA QUESTIONS

1. What is surveying?2. What is reconnaissance survey?3. What is an index sketch?4. What is base line of survey?5. How is the north line of the chain survey map fixed?6. Suppose you are asked to conduct a chain survey in a crowded town. What

would you say?

7. What should be the maximum length of offset?8. How is a station marked on the ground?9. What is the need of reference sketch?10.How will you set up a perpendicular with the help of only a chain or a tape?11.Who are leader and follower, when a line is being chained?12.Why does the field book open lengthwise?13.Why is the scale always drawn in the map?14.What is it necessary to provide tallies in a chain?15.What do you mean by the term ideal triangle?16.What is the principle of compass surveying?17.What is the difference between triangulation traversing?18.What does the term chain angle mean?19.What is a 12cm compass?20.What is the fundamental difference3 between the prismatic compass and the

surveyors compass?

21.How would you detect the presence of local attraction in an area?22.The FB of line is 96030and BB is 27600. How will you adjust the bearing?23.What is local attraction?24.What is declination?25.What are isogonic and agonic lines?26.What do you mean by azimuth?


44/46



27.The FB of a line is = 145030 what is its B.B?28.What are precautions to be taken while shifting an prismatic compass from one

station to another?

29.A compass was properly balanced at the equator. What will be the effect on theneedle if it is taken to the northern hemisphere?

30.What is the angular check of a closed traverse?31.How would you check the accuracy of open traverse?32.What does traverse surveying mean?33.Distinguish between closed and open traverse?34.What is datum surface?35.What does the term GTS mean?36.What are bench marks?37.What is the datum adopted for GTS bench marks?38.What are the types of BM that you know of?39.For any engineering work, how will you get the RL of the starting point?40.What is the difference between a level surface and a horizontal surface?41.What is the difference between the line of collimation and axis of the

telescope?

42.In a particular set up of the level, suppose four readings are taken. How shouldthey be entered in the level book?

43.What is a change point?44.The staff readings on A and B are 1.735 and 0.965 respectively. Which point is

higher?

45.What is the procedure of leveling foot screws?46.How is the level entered?47.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?

48.How will you continue leveling across a river?


45/46



49.How will you continue leveling across a lake or pond?50.What are the arithmetical checks for the HI method and the rise and fall

method?

51.What is fly leveling?52.What are the types of errors in surveying?53.Mention the sources of errors in surveying.54.What are the principles of surveying?55.List the various obstacles that are encountered in chaining.56.Explain the terms check lines, tie lines and reference lines.57.

What are the difference betweenprismatic compass and surveyors compass?

58.What is local attraction and how it is detected?59.Which are the methods used in adjusting closing errors in compass?60.What are the working operations in plane table surveying?61.What is temporary benchmark?62.Why is datum assumed for plotting a levelling operation?63.What is the difference between temporary and permanent adjustment?64.What would you mean by positive RL and negative RL?65.How will you measure the distance between two-points with only a level and

staff?

66.What is contour line?67.Define the terms contour interval and horizontal equivalent?68.Why is the horizontal equivalent not constant?69.In some places consecutive contours run close together and in some places they

are wide apart. What does this mean?

70.How will you distinguish between a depression and a summit by studying thenature of the contour?

71.In a map, it is found that two consecutive contours cross each other. whatwould you comment?

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


46/46


73.What is a contour gradient?74.What is the object of preparing a contour map?75.Define the terms contour line. Contour intervals and horizontal equivalent.76.What are the characteristics of contour line?77.Show with neat sketches the characteristics features of contour lines of the

following: 1. A pond 2. A hill 3. A ridge 4. A valley and 5. A vertical cliff

78.State the uses of contour map.79.What are the different methods of contouring? Describe any method along with

sketch.

80.What is a grade contour? Describe along with sketch how you would locate onein the field.

81.What is the principle of plane tabling?82.What is orientation? Why is it done?83.How are centering and levelling done in plane tabling?84.What are the methods of plane tabling?85.When would you apply resection?86.What is intersection? When it is required?87.When would you apply the 2 points and 3 points problem?88.What do the terms grade triangle and grade circle mean?89.One month after the completion of a plane table survey, it is detected that one

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

field?

90.What type of orientation would you prefer and why?91.What method would you apply for locating inaccessible points?92.What would you mean by the fiducial edge of the alidade?93.What are the different types of alidade?94.What do you mean by strength of fix?95.What are the precautions you have to take while centering the alidade with the

Documents

Surveying Practice r2