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RANGANATHAN POLYTECHIN COLLEGE
CIVIL ENGINEERING
SURVEYING PRACTICE-I
III SEM
PREPARED BY
S.KOWSALYA
1. CHAIN SURVEY`
Exercise No. ......1................ Date :.........
1.1 ACCESSORIES USED FOR CHAIN SURVEY
Aim
To study about the chain, tape and other accessories used for chain survey.
Introduction
Chain surveying is the process of measuring the distances with a chain or tape with other accessories. The principle of chain surveying is triangulation in which the frame work of equilateral or well-conditioned triangles are formed which can be plotted easily.
Equipment’s and accessories used in chain surveying
1. Chain 6. Cross staff
2. Tape 7. Plumb bob
3. Arrows 8. Pegs
4. Ranging rod 9. Hammer
5. Offset rod 10. Field book, Pencil and Eraser
11. Other miscellaneous items like chalk, nails, threads and cords.
1. Chain
A chain is mainly used in chain surveying to measure the distances. A chain may be metric or non-metric. Generally a chain consists of 100 or 150 links each 300 mm or 200 mm in length. The link is made of galvanized mild steel wire 4 mm to 6 mm diameter. The ends of each link are bent into a loop and connected together by means of three rings. The ends of the chain are provided with brass handles with a swivel joint to avoid twisting of chain while handling. The length of the chain is measured from outside of one handle to the outside of the other. Metallic tags or tallies are fixed at every distinctive distance such as 3 m or 5 m to facilitate quick reading of fractions of the chain. Small brass rings are also providedateverymeterlength.
Types of chains
i. Metric chains
Metric chains of length 20m, 30m, 50m and 100m are used now-a-days for measuring the
distances in meters and its fractions.
ii. Non-metric chains
The following are the non-metric chains in which the unit of measurement is foot.
a. Engineers chain
It is 100 feet long and consists of 100 links, each of 1 foot length.
b. Gunter’s chain or surveyor’s chain
It is 66 feet in length, consists of 100 links each being 0.66 foot long.
c. Revenue chain
It is 33 feet long and consists of 16 links. It is used in cadastral survey.
iii. Steel Band or Band chain
It is made of steel ribbon 16 mm wide and is available in 20 and 30 m lengths. It is wound on an
open steel cross in a closed case.
2. Tapes
Tapes are used for measuring the distances in precise work. Tapes are made of different
materials. They are,
i. Cloth or linen tape
ii. Metallic tape
iii. Steel tape
iv. Invar tape
i. Cloth or linen tape
It is made of woven linen strip 5 mm to 15 mm wide and varnished. It is easily affected by damp.
ii. Metallic tape
It is made of linen strip inserted with metallic wires.
iii. Steel tape
It is made of thin steel strip and is available in 10, 20, 30 and 50 meter lengths. It is widely used for
accurate measurements.
iv. Invar tape
It is made of an alloy of steel and nickel. It is used for the work of highest precision.
3. Arrows
Arrows are made of hardened and tempered steel wire of 4 mm diameter and 400 mm long. It is
pointed at one end and the other end is bent into a ring of 50 mm diameter. It is used for marking the
ends of chain length.
4. Ranging rod
Ranging rod is circular in cross-section and 2m to 3m long with pointed metal shoe at one end. It is
painted black and white or red and white alternatively. It is used for marking the stations and for ranging
the lines.
5. Offset rod
An offset rod is similar to ranging rod, but it is provided with a hook at the top for pulling or pushing
the chain through a hedge. It is divided into meters and decimeters with alternate bonds of paints. Offset
rods are mainly used for measuring offsets.
6. Cross staff
It is used to set a perpendicular at a point on a line. It may be,
a. Open cross staff
b. French cross staff and
c. Adjustable cross staff
An open cross staff is a wooden box or block of size 150 mm square and 38 mm deep with two fine
saw cut slits at right angles to each other. The block is mounted on a steel rod 1.2 m to 1.5 m long and
25 mm diameter.
7. Plumb bob
It is a solid cone attached to a thread. It is used when measuring distances along slopes to
transfer points to the ground.
8. Pegs
Pegs are made of wood 25 mm square or steel or iron pegs of 12 mm dia and 150 mm long, tapers
at one end to drive it into the ground. It is used for marking the stations.
RESULTS:
The above accessories like chain tape for chain surveying are stated.
Exercise No. .......2............... Date :..........
UNFOLDING READING AND FOLDING OF CHAIN
Aim;
To practice in unfolding (or spreading), reading and folding the chain.
Procedure
Unfolding the chain
The process of stretching or spreading the chain for measurement is called unfolding the chain.
1. The follower keeps both the handles of the chain in one hand and holds the rest of the bunch
of links in other hand.
2. Keeping both handles in one hand, throws the remainder forward on the ground.
3. The follower directs the leader to take hold of the middle point of the chain and move in the
forward direction.
4. When one half of the chain becomes independent of the other, the follower transfers one
handle to the leader.
5. The follower directs the leader to move in the forward direction until the full chain is unfolded
Reading the chain
Chain can be read from both the ends. While taking the measurement, observe the tag
immediately before the point to be measured. Then count the number of links in the forward direction up
to the point of measurement
Folding the chain
It is the reverse process of unfolding:
1. Bring the two handles together and pull the chain from the middle to stretch it well.
2. Take the middle pairs of links in one hand and the next pair in other hand.
3. Place pair of links in one hand across the links in the other hand obliquely.
4. Continue the process until the complete chain is folded so that the entire bunch of the chain
could be
gripped in one hand.
5. Tie the bunch of chain tightly with a piece of cord.
RESULT:
Unfolding and folding of chain or practiced.
Exercise No. ........3.............. Date :.........................
CROSS STAFF SURVEY
Aim
To conduct the cross staff survey and to find the area of the given field by plotting the same with
one chain line and at least two offsets on either side of chain line.
Introduction
The chain survey which is carried out to prepare cadastral maps for locating the boundaries of
each field and to determine their areas is called cross staff surveying.
Equipment’s required
1. A cross staff (or) optical square
2. Two chains
3. Arrows and ranging rods
4. A plump bob
Field Procedure
1. Run a chain line (baseline) through the center of the field.
2. With this base line the area is divided into a number of right angled triangles and trapezoids.
3. Using cross staff, offsets for each turning point of the field boundary and their chain ages are
noted in a field book as usual.
4. The area is computed directly from the field book recording or by plotting the same.
Calculation:
s.no fig chain age base offsets mean Area M
2
Result
The area of the given field = ____________
Exercise No. ..........4............ Date :..............
CHAINNING AND RANGING A LINE
Aim
To practice in chaining and various methods of ranging a line to measure distance between two
points.
Chaining a line
Equipment’s and Persons required
Two chainmen with a bundle of ten arrows, a ranging rod and a chain.
Procedure
1. At the beginning, the follower keeps the end of the rear handle at the starting point in contact
with the arrow.
2. The leader stretches the chain, taking the other handle and goes forward along the line.
3. The follower directs the leader to come exactly in line.
4. The leader puts a mark and stretches the chain properly. Then he holds the arrow against the
end of the handle and pushes it vertically into the ground.
5. Then the leader drags the chain forward till the rear handle arrives at this arrow point.
6. The follower keeps the arrow inside the handle and stands with his two heels on the chain and
directs the leader to fix his arrow in line as done earlier.
7. The measurements are continued till the line finishes.
8. The total length of the line will be obtained by the number of arrows in the follower‟s hand
Which means the number of chain lengths measured and the fractional length of the least line by
counting the links.
Ranging a line
The process of establishing intermediate points in measuring a long survey line or prolonging a
straight line is called „ranging‟.
There are two types of ranging
i. Direct ranging, when the end stations are indivisible
ii. Indirect ranging, when the end stations are not indivisible
Equipment’s required
1. 4 or more number of ranging rods
2. Cross staff
3. Line ranger
4. Plumb bob
5. A chain or tape
Procedure
i. Direct ranging
There are two methods of direct ranging (a) Ranging by eye (b) Ranging by line ranger.
a. Ranging by an eye
1.To range a line, AB first ranging rods are fixed at the ends of the line.2. The follower stands 2m
behind the ranging rod at the starting point A.3. The leader holds a ranging rod at arm‟s length at C,
approximately on the line AB.4.The follower then directs the leader to move his ranging rod to the right or
left as required till all the three ranging rods are in one line.5. The leader then fixes the rod in the
ground to establish the point „C‟ in line with A6. Similarly, other points are established on the line AB.
b. Ranging by line ranger
Line ranger consists of two right angled isosceles triangular prisms placed one above the other
which reflects the images of ranging rods at the terminal points To locate an intermediate point „C‟ in line
with A and B proceed as follows1.Holding the line ranger at eyelevel, stand approximately in line n
2.Move the instrument until the image of one of the ranging rods is seen in the field of view. 3.
The ray from A, enters the upper prism, gets reflected from hypotenuse, LQ and enters the eye at
right angles to AB. Similarly the ray from B, enters the lower prism, gets reflected from the hypotenuse,
PM and enter at right angles to BA4.Thus the images of A and B are seen in upper and lower prisms5.
If the point C is not in the line, the two images will be separated Move the instrument backward and
forward until two images appear one above the other exactly in same vertical line.7. Now the point C
is vertically under the center of the line ranger and can be transferred to the ground by plumb bob.
Result Changing and ranging a line has been done.
Exercise No. .........5............. Date.................
CHAIN SURVEY TRAVERSE AND PLOTTING
Aim
To conduct the chain survey traverses around a building and plot the existing building.
Chain Survey Traverse - Introduction
Traverse is the frame work of survey lines whose directions and lengths are measured. The offsets
necessary to locate the details are taken in the usual way and recorded in the field book.
In chain traversing or chain angle method, the entire work is done by chain and tape. The chain
angle between the successive lines of the traverse is fixed by measuring tie lines. To plot the existing
building, a chain traversing is to be run around the building as shown in fig. 1.12.
Fig. 1.12 Chain angle methods - Closed traverse
To measure chain angle
To measure the chain angle SPQ, keeping P as
centre and radius equal to 20m, draw an arc by a tape,
intersecting PQ at a2 and PS at a
1. Bisect a
1 a
2 at M. Then,
Sin = 𝛼/2 = a2 m/a2p =2a2m/2a2p
= a1a2/40
Men and equipments required
The team will consist of the following members:
1. Surveyor
2. Leader
3. Follower and
4. Two or more helpers.
Equipments
1. A chain (20m or 30m)
2. A metallic tape (20m or 30m)
3. 10 arrows.
4. Ranging and offset rods.
5. An optical square or cross-staff
6. A plumb bob
7. Wooden pegs
8. A hammer
9. A field book, pencils and eraser.
10. Other miscellaneous items like chalk, nails, threads and cords.
Field work procedure
Field work of chain surveying is carried out in the following steps :
1. Reconnaissance
2. Marking stations
3. Running survey lines.
1. Reconnaissance
In this, the surveyor walks over the area to have the general idea about the main features and
boundaries. He then prepares a neat hand sketch in the field book called „key plan‟ which shows the
boundaries, main features, positions of chain lines and stations. The north direction is drawn on the right
hand top corner by an arrow pointing vertically upward.
2. Marking stations
After the reconnaissance survey, all survey stations are marked accordingly with reference to two
or three permanent objects. A brief description of each survey station is given and the reference sketches
are drawn in the field book.
3. Running survey lines
1. Ranging is done between the end stations of a survey line.
2. A chain is stretched in true alignment keeping one end of the chain at the starting station.
3. A arrow is fixed at the other end of the chain while it is kept laying on the ground.
4. The surveyor walks along the chain line and takes offsets to adjacent points on the right or left
sides of the chain line.
5. Chain ages and offsets are recorded in the field book.
6. Process of chaining and offsetting is repeated until the end of the traverse line is reached.
7. Other lines are similarly completed.
Recording in the field book
The recording starts from the bottom of the last page of the field book. The complete record of the
chain survey should include:
1. The date of survey
2. The name of the survey site
3. Name of the surveyor
4. A page index of the lines
5. A general layout plan of the lines
Plotting a chain survey
Plotting includes preparation of plans and computation of their areas with the help of field notes.
The plotting may be done in the following steps:
1. The scale is to be decided before field work is commenced.
2. The drawing sheet is to be placed and fixed on the drawing board.
3. The map should be oriented in such a way that the north line points more or less upwards
Accordingly the longest line of the frame work should be drawn to scale.
4. The drawing of the framework should be completed.
5. The points are marked according to the chain age and offset along the different lines of the
framework.
6. The map should be made complete in all respects and the meridians are to be drawn at the top
right corner space. To the bottom right corner of the sheet in 185mm × 65mm rectangular block should be
written the title of the survey, the scale of the survey map, conventional symbols used, the date of survey,
etc.,
7. Lastly the inking should be completed.
Result :
The chain survey traverse around a building and plot the existing building is conducted.
2. COMPASS SURVEY
Exercise No. ........6.............. Date :.........................
PRISMATIC COMPASS- SETTING UP AND OBSERVING BEARING
Aim
To study about Prismatic compass and practice in setting up over a station and observing bearing.
Introduction
In traversing, the direction of the line is measured using angle measuring instruments. The
following instruments are generally used:
1. Magnetic compass
a. Prismatic and
b. Surveyor‟s.
2. Sextant
3. Theodolite.
Prismatic Compass
The essential features of a prismatic compass are :
1. Magnetic needle
2. Line of sight
3. Graduated circle.
Theprimatic compass can either be used as a hand interment or can be fitted on a tripod. The main parts
of the prismatic compass are shown in fig
Prismatic compass
Setting up of Compass
Fix the prismatic compass on the tripod vertical spindle which is carried in a ball and socket joint.
The setting up is done in the following sequence of temporary adjustments.
1. Centering
Centering is the process of keeping the instrument exactly over the station. This is done in the
following ways:
1. The stand is to be suitably placed over the station.
2. Suspend the plumb bob from a point just below the pivot point.
3. Adjust the tripod legs such that the point of the plumb bob just either touch the station or just lies
about it.
4. In absence of a plumb bob, drop a pebble (small stone) from the point just below the pivot point.
5. Adjust the tripod legs such that the pebble dropped is to strike the station point.
6. The movement of tripod legs is now clamped.
2. Leveling
Leveling is the process of bringing the compass in the horizontal plane with the help of the ball and
socket joint. The compass box is to be so oriented that the graduated ring and hence magnetic needle
can rotate freely on a horizontal plane.
3. Focusing the prism
The position of the prism is to be so adjusted by moving up or down so that the graduations on the
ring are clearly and sharply readable.
Observing a bearing with a Prismatic Compass
To observe the bearing of a line AB proceed as follows:
1. Centre and level the compass over the station A.
2. By seeing through the eye vane turn the compass
towards the object B which is bisected by the thread (or horse
hair) in the sight vane.
3. Check that the vane slit, hair of the object vane and the
object should be in one line.
4. Before taking observations, the vibrations of the needle
should be arrested by gently pressing the break pin knob below
the sight vane.
5. Note the reading by moving the eye upwards a little and taking observations through the prism
where the hair line appears to cut the graduation.
6. The reading is the bearing of AB as shown in fig. 2.2
Result:
About prismatic compass and practice in setting up over a station and observing bearing are study.
Exercise No. .........7............. Date :.........................
CLOSED COMPASS TRAVERSE, FINDING THE INCLUDED ANGLES AND PLOTTIND
Aim
To run the closed compass traverse, finding the included angles from the bearings and plot the
traverse.
Introduction
Traversing is that type of survey in which the survey lines form the frame work and the directions
and lengths are measured using angle measuring instrument and a tape (or chain) respectively. When
the survey lines of a traverse form a circuit which ends at the starting point, it is known as closed traverse.
If the circuit ends elsewhere, it is said to be an open traverse.
Equipments required
1. A magnetic compass (Prismatic or surveyor‟s)
2. A metric chain (20 or 30m)
3. A metallic tape (20 or 30m)
4. 10 arrows
5. Ranging and offset rods.
6. An optical square or cross-staff
7. A plumb bob
8. Wooden pegs
9. A hammer
10. A field book, pencils and eraser
11. Other miscellaneous items like chalk, nails, threads and cords, etc.
Field work procedure
The field work and the recording of the field book are in similar manner as in the case of chain
survey, with the only difference, that the bearing measurements are to be observed and recorded in the
appropriate places. The traverse may be run in clockwise or anticlockwise direction.
The traverse consists of:
1. Reconnaissance
2. Marking and referencing of stations
3. Running of survey lines
4. Picking up of details
5. Booking of field notes.
To survey an area bounded by closed traverse stations ABCDEFGHA the following steps are
involved:
1. Go round the area to be surveyed for reconnaissance, prepare a key plan and fix survey stations.
2. Centre and level the compass at the starting point A.
3. Orient the compass accordingly and take F.B. of AB and B.B of HA.
4. Measure the length of first line AB and take offsets to the objects on either side of the line AB.
5. Now, shift the compass to second station B, and take F.B of BC and B.B of AB.
6. Measure the length of line BC and take offsets to the objects on either side of the line BC.
7. Similarly, repeat these operations at each of the subsequent stations till the last station is reached.
8. Record the observations in the field book in the following tabular form:
Observation:
RESULT:
They include ding angles 5400 Hence ok.
Points FB BB
AB
BC
CD
DE
EA
Exercise No. ....8.................. Date:.........................
COMPUTATION OF DISTANCE BETWEEN TWO ACCESSIBLE POINTS
Aim
To compute the horizontal distance between two points when
their bases are accessible. n
Equipments required
1. A Prismatic compass
2. A chain or tape
3. Peg etc.
Procedure
To find the distance between the two accessible points P and R proceed as follows:
1. Select the instrument station “Q” so as to form an equilateral triangle in plan with the points P and R.
2. Centre and level the compass over the station „Q‟.
3. turning the compass in clockwise direction, orient it towards the point P.
4. Note down the reading as the bearing of line QP which is denoted by QNP
.
5. Again, turn the instrument clockwise orient the compass towards the point R.
6. Note down the bearing of QR as QNR
.
7. From these two bearings, compute the included angle at Q of triangle PQR by plotting a diagram.
In fig. 2.4, = (360 – QNP
) + QNR
8. Measure the distance of points P and R from the instrument station Q.
9. The distance between the two accessible points P and R can be computed using the formula as follows :
PR2=(QP2 + QR2 – 2 × QP × QR × cos
PR = √(QP2 + QR2 – 2 × QP × QR × cos
Observations
Bearing of QP, QNP
=
Bearing of QR, QNR
=
Distance of QP =
Distance of QR =
∅ =PR=√(QP2 + QR2 – 2 × QP × QR × cos
Result
Included angle, =
Distance, PR =
Exercise No. ...........9........... Date :.................
COMPUTION OF DISTANCE BETWEEN TWO INACCESSIBLE POINTS
Aim
To determine the distance between two points when their bases are in-accessible.
Equipments required
1. Prismatic compass
2. Chain or tape
3. Ranging rod.
4. Cross staff
5. Pegs.
Procedure
Let the survey line PQR cross the river as shown in fig..
The distance between the inaccessible points Q and R being near and distant banks respectively, can be calculated by the bearings of the lines joining the points from a station „S‟ as follows :
1. Set the perpendicular QS to some convenient distance, say 50m, at Q either left or right side of the line PQR.
2. Set up the compass at station point S.
3. Observe the bearing of point „R‟ at station „S‟, say SNR
.
4. Locate the point P' on line PQ, by setting the bearing as SNP‟
at S, such that SNR
– SNP‟
= 90º.
i.e., SNP‟
= SNR
– 90º.
5. Measure the distance between the points P‟ and Q.
6. Now, from similar triangles, QRS and P‟QS.
QR=QS2/P‟Q
Observations
Length of line, QS =
Bearing of line, SR, SNR
=
Bearing of line, SP',
SNP‟
= SNR
– 90º
Distance of line, P'Q =
Calculation:
√D12+D2
2 -2∗ 𝐷1*D*2cos
Result
The distance between two in-accessible points = ____________ m
3. LEVELLING
Exercise No. ......10................ Date……....
Aim
To study about the leveling instrument practice in temporary adjustments, taking staff readings and
booking.
General
The art of determining the relative elevations of points on the surface of the ground is known as
„Leveling‟. For this the instrument, a level is used with other equipments of leveling staff, chain, etc.
A Level
The instrument which is used for leveling is known as a „Level‟. The levels may be classified as
1. Dumpy level
2. Wye or Y-level
3. Reversible level and
4. Tilting level
The level irrespective of its type essentially consists of,
1. Leveling head with foot screws
2. Telescope and
3. Level or bubble tube.
The essential parts of a dumpy level are shown in fig. 3.1.
Dumpy literally means short and thick. It consists of a telescope rigidly fixed in its support. Its leveling
head consists of two parallel plates with either three or four foot screws. The upper plate is known
„Tribrach‟ and the lower plate is known as „Trivet‟ screwed on to the tripod stand. Temporary adjustment
of a Level
l Procedure
The adjustments which are made for each setting of a level, are called temporary adjustments. These
include
1. Setting up the level
2. Leveling up
3. Elimination of parallax.
1. Setting up the level
This includes,
a. Fixing the instrument on the tripod
b. Approximate leveling by leg adjustment.
a. Fixing the instrument on the tripod
i. Unfold the tripod, spread the legs and setup on the ground firmly to hold the level at convenient
height of the observer.
ii. Hold the instrument in one hand and lift the same from the box.
iii. Fix the instrument on the tripod by turning round the leveling head with the other hand.
b. Approximate leveling by leg adjustments
i. The foot screws are brought to the middle of their run.
ii. Fix two legs firmly into the ground.
iii. Move the third leg radically and circumferentially until the instrument is leveled approximately.
2. Leveling up
After setting up the level, accurate leveling is done with the help of foot screws and with reference
to the plate levels. The object of leveling up the instrument is to make its vertical axis truly vertical.
The following steps are followed to level the instrument with a three screw head
Turn the instrument until the longitudinal axis of the plane level is parallel to a line joining any twolevelling
screws.
ii. The bubble is brought to the centre of its run by turning both the foot screws inwards or outwards
simultaneously.
The bubble moves in the same direction as left hand thumb.
iii. Rotate the instrument through 90º until the axis of the plate level coincides the line joining the
thirdfoodscrew
and the midpoint of the line joining the first two screws. (Fig.(b)).
iv. Now, bring the bubble to the centre of its run by turning the third foot screw.
v. The plate level is brought back to its original position by turning the instrument intone same
quadrant and repeat step (ii) till the bubble is central.
vi. Rotate again through 90º and repeat step (iv)
vii. Repeat the steps (i) to (vi) till the bubble remains central in both the positions.
viii. Turn the instrument about vertical axis through a complete revolution. If the instrument is in
correct adjustment, the bubble will remain in the centre of its run. If not, it needs permanent adjustment.
3. Elimination of Parallax
An apparent change in the position of an object caused by the change in position of the observer‟s
eye is known as „parallax‟. This can be eliminated in two ways:
a. Focusing the eye piece for distinct vision of the cross-hairs.
b. focusing the objective to bring the image of the object in the plane of cross hairs.
a. focusing the eye-piece
i. Direct the telescope either towards the sky or hold a sheet of white paper in front of the
objective.
ii. Move the eye-piece in or out till the cross-hairs appear sharp and distinct.
b. focusing the objective
i. Direct the telescope towards the leveling staff.
ii. Turn the focusing screw till the image appears clear and sharp.
iii. The image so formed must be in the plane of cross hairs.
Taking Staff Readings
The staff readings are taken as follows:
1. The instrument is setup and carefully leveled (Temporary adjustment is done)
2. The staff is held vertically over the station; for this, the staff man stands behind the leveling staff
with his heels together and bottom of the staff in between his toes and holds the staff in between the
palms at the height of his face.
3. The telescope is directed towards the staff by the instrument man and is focused by using
focusing screw and move the telescope such that the staff is exactly between the vertical hairs of
diaphragm.
4. If the bubble on the telescope is not at the centre, the same is centered, by using the
corresponding foot screws. The readings may now be taken.
Booking the staff readings
The staff readings are recorded in level field book in one of different forms, i.e., in one column, two
columns or three columns. In three column method the B.S, I.S and F.S are recorded in separate
columns. Points to be kept in mind while booking readings in three column method.
1. The readings should be entered in the respective columns in order of their observation.
2. The first entry on the page is always a back sight and the last one is always a foresight.
3. The foresight and back sight of the change point should be written in the same horizontal line.
4. The height of plate of collimation should be written in the same horizontal line, opposite to the
B.S.
5. In carrying forward the readings from one page to the next and if the last entry happens to be an
intermediate
sight, it is entered in both I.S and F.S columns and in the B.S and I.S. columns as a first entry on
the next page. The remaining entries against it should also be repeated on the next page.
6. Change point, bench marks and other important points should be briefly described in the last
column of „Remarks‟
Result
This component part when leveling in statement in type of level studied.
Exercise No. ........11.............. Date:.........................
FLY LEVELLING –REDUCTION BY HEIGHT OF COLLIMATION
Aim
To run fly levels connecting the given points and reduce their levels by height of collimation
method.
Fly leveling - Definition
The operation of spirit leveling which is employed to determine the level difference between two
consecutive points, quite far away is called fly leveling. It is also employed to carry out the
reconnaissance of area.
Equipments required
1. A level with tripod
2. A leveling staff
3. Level field book
Field work procedure
To find the level difference between a point A and the other point B far away from A, proceed as
follows
Fig. 3.3 Fly leveling
1. Choose a temporary B.M near by the point A.
2. Setup the level at „O1‟ ensuring that the line of sight intersects the staff to be held at B.M and that
at A. Level it accurately.
3. With the bubble central, take the B.S reading on the staff held at B.M.
4. With the same setup of the level, take the I.S. reading on the staff held at the point A.
5. Select a change point „C‟ and take foresight reading on the staff held at „C‟. The change point
should be selected such that the staff points of B.S reading and F.S readings are at equidistant from the
instrument position.
6. Shift the instrument to O2 setup and level it accurately.
7. With the bubble central take B.S. reading on the staff held at change point „C‟ again.
8. Select a point D equidistant from the instrument station O2 and take the F.S reading on the staff
held at D.
9. Repeat the process until the F.S. reading is taken on the staff held at point „B‟.
10. Reduce the levels of all staff points with reference to the level of B.M. Then the difference of
level of the points A and B is determined.
Reduction of levels by height of collimation
In this method, the elevation of plane of collimation (H.I) is determined for every set-up of the
instrument and then the R.Ls of the points are obtained in the following manner.
1. Determine the elevation of the plane of collimation for the first set up of the level by adding the
B.S. reading tithe R.L of the B.M.
2. Obtain the reduced levels of the intermediate points and first change point by subtracting the
staff readings taken on these points (I.S and F.S) from the H.I.
3. Shift the instrument to the second position and set up a new plane of collimation by adding the
new B.S .taken on the C.P. from the second position of the level to the R.L of the first change point.
4. Find out the R.Ls of the successive points and the second change point by subtracting their staff
readings from this H.I or H.Cl.
5. Repeat the process until all the R.Ls is worked out.
Note: The following statements may bear in mind while reducing the levels by H.I or H.Cl.
method.
R.L + B.S = H.Cl.
H.Cl. – F.S or I.S = R.L
6. For the entire work the arithmetical check will be
B.S ~ F.S = Last R.L ~ First R.L
Observations and calculation
station B.S I.S F.S H.C R.L
Result
The R.Ls of the given points is,
Exercise No. .....12................. Date :.........................
FLY LEVELING BY RISE AND FALL
Aim
To run fly levels connecting the given points and reduce their levels by rise and fall method.
Fly leveling - Definition
The operation of spirit leveling which is employed to determine the level difference between two
consecutive points, quite far away is called fly leveling. It is also employed to carry out the
reconnaissance of area.
Equipments required
1. A level with tripod
2. A leveling staff
3. Level field book
Field work procedure
To find the level difference between a point A and the other point B far away from A, proceed as
follows : (Refer to fig. 3.3)
1. Choose a temporary B.M near by the point A.
2. Setup the level at O1, ensuring that the line of sight intersects the staff to be held at B.M and that
at A level it accurately.
3. With the bubble central, take the B.S reading on the staff held at B.M.
4. With the same setup of the level, take the I.S. reading on the staff held at the point A.
5. Then select a change point „C‟ and take F.S reading on the staff held at „C‟. The change point
should be selected such that the staff points of B.S reading and F.S readings are at equidistant from the
instrument
station.
6. Shift the instrument to O2, setup and level it accurately.
7. With the bubble central, take B.S. reading on the staff held at change point „C‟ again.
8. Select a point D equidistant from the instrument station O2 and take the F.S reading on the staff
held at D.
9. Repeat the process until the F.S. reading is taken on the staff held at point „B‟.
10. Reduce the levels of all staff points with reference to the level of B.M. Then the difference of
level of the points A and B is determined.
Reduction of levels by rise and fall
In this system, the difference of levels between consecutive points are determined and then the
R.Ls of the points are obtained in the following manner.
1. Determine the difference of levels between consecutive points by comparing their staff readings.
2. Obtain the rise or the fall, according to the staff reading at the point is smaller or greater than
that at preceding point.
3. Find out the R.L of each point by adding the rise to or subtracting the fall from the R.L of the
preceding point.
4. For the entire work, the arithmetical check will be,
B.S ~ F.S = Rise ~ fall
= Last R.L ~ First R.L
Field work and Calculation
STATION BS IS FS RISE FALL R.L
Result
The R.Ls of the given points is,
Exercise No. .......13............... Date :........................
FLY LEVELING –WITH INVERTED READING
Aim
To run fly levels connecting the points which require inverted reading and reduce their levels.
Equipments required
1. A level with tripod
2. A leveling staff
3. Level field book
Field work procedure
The procedure of leveling work for fly levels and reduction of levels are carried out in the usual
way. In doing so, some common difficulties faced in leveling one of it is, when the B.M or the staff point is
above the line of collimation. To overcome this, it is required to observe inverted reading as explained
below:
1. Hold the staff inverted on the overhead point (B.M) keeping the foot of the staff touching the
point.
2. Observe the staff reading, which is the inverted reading.
3. The height of line of collimation is equal to the R.L of B.M minus the B.S.
4. In case, a F.S. or I.S. is taken on an inverted staff, R.L of the point is obtained by adding the F.S
or I.S. reading to the level of field book, the inverted staff readings are entered with a negative sign.
Observations and calculations
STATION BS IS FS RISE FALL R.L
Result
The R.Ls of given points are=
Exercise No. ..........14............ Date :.........................
CHECK LEVELING
Aim
To run check levels connecting the given points, reduce and check their levels.
Check leveling - Definition
It is the operation of running levels to check a series of levels, which are already taken. It is also done to accurately establish a B.M. near the site of work from a known B.M. Check levels are carried out at the end of each day‟s work, starting from the last to the first point. If the leveling work is correct, the R.L of the first point assumed at the beginning will be equal to that obtained from the check levels.
Generally check leveling is done using a single leveling instrument with a single staff or two leveling instruments with a single staff.
Equipments required
1. A level with tripod
2. A leveling staff
3. Level field book
Field work procedure
The field procedure and reduction of levels of points are same as that for fly leveling.
The following is the procedure of leveling work in the field. (Refer to fig. 3.4)
1. The instrument position marked (1) is selected, such that it can observe staff readings on the maximum number of points 1, 2, 3, The points are shown on plan in fig. 3.4 (a) and in elevation as marked1, 2,3Respectively in fig. 3.4 (b) along with the bench mark marked B.M.
2. The instrument is setup and leveled up over the station point (1).
3. Observe the reading on the staff held at B.M.
Let us express the reading in accordance with the convention aij, where „a‟ is the staff reading on
thethpoint for the ithe position of the instrument.
4. If the R.L of B.M is „h‟ and a1
BM is the staff reading on the B.M. i.e., the first staff reading which is
termed as back sight or B.S. Then the height of the instrument position (1) may be designated as
H.I (1) = h + a1
BM
or H.I = R.L + B.S
5. In a similar way, a1
1 and a2
2 are, although, obtained, the reading of the staff at the point 3 may
not be obtainable. Hence, a
12 is the last staff reading from the instrument position (1), it is termed as foresight or
F.S.between B.S and F.S, sights like a1
1 are called intermediate sights or I.S. This forms the first stage in
theseriesof setups.
6. Now, the R.L of point (1) = H.I (1) – a
21
and the R.L of point (2) = H.I (1) – a
12
or R.L = H.I – I.S or F.S
Fig. 3.4 Procedure for leveling
7. The instrument position has to be shifted to instrument position (2) to take observations on other many points as possible.
8. To calculate H.I (2), first of all, the staff reading a2
2 should be obtained, because the R.L of the
pointalreadycalculated.At point 2, a1
2 is the F.S for previous instrument position and a2
2 is the B.S for
subsequent instrument position. Such a staff point is termed as change point or C.P.
9. The R.L of line of collimation now is,
H.I (2) = R.L of the point (2) + a2
2
This forms the second stage in the series of instrument setups.
10. After obtaining a2
3, a2
4 etc., the R.L of points can be computed as,
The R.L of point (3) = H.I (2) – a2
3
The R.L of point (4) = H.I (2) – a2
4 etc.
11. This procedure may be continued to the completion of the leveling work.
12. For the entire data, the arithmetical check will be,
B.S ~ F.S = Last R.L ~ First R.L
Observations and calculation
Station B.S I.S F.S H.C R.L
.
Result
The R.Ls of given points before and after taking check levels are given below :
GPS
Exercise No. ..........15........... Date :.........................
READING OF VARIOUS MAP LIKE
a. DISTRICT MAP
1. What is a district map?
A district map is simply a drawing in 2-D of a landscape or area for the state of country. Using this
map any visitor can find the details within map of that district, what the place looks like that you are going
to, and you can see what landmarks and features you will pass on the way to your destination. Maps help
you to know are you going in the right direction to arrive at your destination safely and quickly.
2. What are all the different symbols identified?
The delineated boundary of the given district is shown in doted lines. Importance features such as
road, railway line, and river which presence within this distinct are also shown with appropriate legend.
Places such as district head quarters, major town, and other town for this district are positioned with of
circle with dot, square block and dot respectively. Name of those places are also represent with English
language.
3. How direction is looked upon?
A north direction is printed at the top of the sheet. Through that it is easy to understand where east,
south and west are and also to know which our left is and our right hand.
B.TALUK MAP
Talk is a series of parcel land of number revenue villages of this district. The delineated boundaries of
thoserevenue village are traced with continuous line and numbered with numeric. A table which shows
the name and number of such revenue village for the given district.
Exercise No. ..........16.......... Date :.........................
STUDY OF HAND HELD GPS
GPS –The basics
GPS relies on a constellation of 24 satellites orbiting at an altitude of 10,9000 miles. The GPS unit
receives an atomic time code form fees satellites and then ses triangulation to compute a 3-d location
accurate to within a four meters.
The GPS can be used to record locations and routes that the unit is following GPS can also calculated
trip time elevations and a number of other variables depending on the types of unit.
The basic unit
The given figures show the three segment of a typical hand held GPS.Description of each
component are given below.
Buttons:
Menu m-accesses the main menu.
PAGES/GO TO- Pages through the navigation screens.
ZOOM IN –Zoom in one the map showing more area and less detail.
ZOOM OUT –Zoom out from the map showing more area and less detail.
Cursor pad –Pans around the map screen.
Enter – Accesses the contextual menu.
Escape –If the cursor has been panned to a location other than your present position,return the map
to be centered on your present position.
Navigation screen map screen overview:
The map screen is the most commonly viewing screen while using this GPS.Each time it
shows number symbol for specific usage is given below:
A - Battery level.
B – Saved way point
C – Present position marker.
D – Map scale indicator.
E – North indicator.
F – Satellite status.
G – Time of day
H – Map area.
Cursor:
There are two important cursors on the map screen ,the present position cursor and
the panning cursor.
Present position cursor.
Panning cursor. The red do around the panning cursor indicates the
direction of your present position.
Additional navigation screen
Current location screen:
The current location screen provides general information about your current
location.
Large data screen:
This screen allows you to view four navigation fields in a large type of face that
is easy to read, even from a distance.
Speedometer screen:
This screen display your current speed, your maximum speed and two
odometers in a large easy-to-read type.
Compass screen:
The compass screen display your heading using and easily identifiable
compass graphic.
Satellite status:
This screen graphically displays the satellites and their signal strength that are
being used to computer your location.
The keypad:
The keypad is used to enter names, notes, latitude, longitude or data that user
needs to enter. Use the cursor control to more around the keyboard and pres enter for
the desired character or function.
Exercise No. ..........17......... Date :.........................
Measurement of latitude and longitude using handheld
Aim:
Measurement of latitude and longitude of a given point using handheld GPS.
Instrument required:
Handheld GPS.
Procedure:
Held the GPS over the point to which latitude and longitude required.
Press the power button of GPS.
From the map screen of GPS, press the menu button.
High light “ create” and press enter.
Highlight “ way point “ and press center.
Select “current location “.
Current location displays the way point screen with the coordinates.( LAT AND
LONG ) for a present location and recorded it.
Optional:
Use the PAGE/GO to button to access option.
The field can be modified to customize the way point.
Icon:
Highlight the icon and press enter to display all possible icons that can be used to
represent your waypoint icons that can be used to represent your waypoint. Select the
desired icon and press to accept the close the window.
Name:
[Default “ GCXXX”]. Select the waypoint name field and press enter to display the
keyboard. Enter the name and select the green button.
Location:
The latitude or longitude fields and press enter to bring up the keyboard that can be
used to enter the desired data.
Difficulty:
Assign a difficulty rating to this point.
Terrain:
Indicate the type of terrain the point is located.
GC type:
Select the suitable type.
Hint:
Field for including hints about the point size.
Data:
Enter the data of the survey.
Select to accept the information and sere the point.
Result:
The observed latitude and longitude of a given point=lat/long
EXP NO 18 DATE…………….
SELECTION OF ROUTING USING HQANDHELD GPS CREATING A ROUTE
AIM:
Selection of routing by connecting the points using hand held GPS.
Instrument required:
Handheld GPS
Procedure:
1. Let1, 2, 3, 4, and5 are the given points of a route
2. Access the main menu highlight create and press enter.
3. Select Route from the create menu.
4. Select the starting location for the route.
5. Held the GPS over the starting point (1) to which latitude and longitude is a required.
6. Current location display the way point screen with the coordinate‟s forpoint1 location
filled in
7. After selecting the starting location the Route screen is displayed.
8. Select add point to repeat step 5 to continue adding subsequent waypoints of the
route.
9. Select done when the last point of the route is complete.
10. Select save route.
11. The save route screen is displayed.
12. Highligth the Route name and press enter to assign a name to the route
13. Highligth the alert button to turn alerts for this route on or off.
14. Select save to store the into memory.
Result
The route is selected by connecting the point with the help of hand held GPS.
