Civil Engineering
Department of
EXPERIMENT NO-1(B)
the survey line
offset along
Linear
Measurement by Tape: Laying perpendicular
M:
APPARATUS:
rods, Cross-staff, Optical
Chain, Tape, Ranging
Square, Arrows
SLITE
SLITE
CROSS STAFF
SLOTE C/S STAFF
Cross staff
perpendicular
i.e. taking
setting
out accurate
if great
used for but not very
THEORY: method,
i n s t r u m e n t
and quicker
theodolite.
simplest
ross-Staff is
the
is
easier out by the is
line. It
carried
be The head
2) the leg.
chain should
OIsets from a
the
work the head 4cm deep.
is desired, two parts 1) or
diameter
CUracy consists 15cm
side fixed two
Type lines a r e
simplest in shape about these t w o at
the end of which are
round
The or
of sight
to another.At
staff:
cross octagonal lines
pen block angles T hese
slit
two
a b o u t 3cm
in
wooden
right m a d e them. or pole
e of two
lines at
slits in o n a staff wooden
i t is
scribed tixed
having is
strip
metallic .The
head
PUnts of one
another
right
angles to 1.5m
length.
lameter and
1.2 to
Rosic Ciil Fnaineering
Department of Civil Eng
The signs or
symbols for the revealation of
the above surface features are presented as follows:
Triangulation Station. 2. Traverse station
3. Tie station. 4. Chain line.
5. Wood fencing. 6. Pipe railing. 7. Wire fencing. 8. Demarcated property
boundary.
9.Undermarcated 10. Compound wall. 11. Stream. 12. Riveer.
property boundary.
13. Cart track. 14. Cana. 15. Railway line. 16. Railway double
line.
muImiiII
HHHHH+* HHHH*
17. Unmetalled road. 18.etalled road. 19. Pucca building. 20. Katcha building
21. Hedge 22. Trees. 23. Woods. 24. Orchard.
25. Cultivated land. 26. Swamps. 27. Culvert. 28. Bridge.
29. Embankment. 30. Cutting. 31. Railway bridge. 32.Temple.
miiiIIL
34. Church. 35. Pond or lake. 36. North line.
33. Mosque.
La
40. Pucca drain.
37. Gates. 38. Well. 39. Bench mark.
BM15.000
42. Electric line. 43. Shed. 44. Gate and wali.
41. Katcha drain.
-
47. Foot path. 48. Lawn.
45. Pasture. 46. Cemetry
Department of Civil Engineering
PROCEDURE-
) To find the foot of the perpendicular from the object the eross staff is held
approximately in position and one pair of slits is directed in the direction of the
ranging rod fixed at the forward and the chain line. The observer then looks
through the other pair of slits and sees whether the particular object is bisected or
not. If not the cross staff is moved to and from till the necessary
bisection is
obtained. Before noting down the foot of the perpendicular care
chainage of the
see that one pair of slit is the direction of chain or
not. While
must be taken to
shifting the position of the cross-staff it may get twisted and hence precaution is
necessary.
line at a given point one pair of slits is
2) To set a perpendicular to the chain
at the ranging rod fixed at the
oriented in the direction of chain line by looking
of slits ranging rod is fixed in the
forward and by looking through the other pair
this pair.
direction of the line of sight provided by
ESULT:
line object are created using cross-staff survey
arious perpendicular to the chain
(8) Viva- 2uestions
het is the U&ef Cross - s tatf
Coss-tqff is Used to Set out the erpendicular
The
odi'rctions foT offrets.
wha is the meamim1 t offset in Surveyimj?
The ateral mea SUment ken trom an object
t h e chain me.
How
How many
man mumberTs ot a w are egu're d tor chaim
chaimn
SUrvey ?
Gene yallyy lo aows Cmarking Pins) a Hd ith
a chain.
Mow Many inks at m a 20 mmetmc c hain
loo links 1 link 20 Cm
what is he pmincipal of
sUrYy
Two basic Pm'neiples of Su Yveyiny at
Always
Always woTk trom whole to +he part, and
To locat a mew stution by at lengt two
measUYements Tnear oY anjular) from ixed
refence points.
Depurtment of Civil Engineer1ng
EXPLNMENT NO- a)
AJM Levelling: Using Tiaing Dunap utomatic Level: To dtenmine the reduced kvels
in iosed circuinL
APPARATUS: Dumps ienel. eveling aff
Figure-
ETCLE
NG SRE
Duups Level
THEORY
Levelling: The art of detennining idpresenting the relative height r clevation of different
objetpuints on the surlace of earth i alled leveling. It deals with measurement in vertical
plane 15 leveling operatin. the relativ position oftwo points is known whether the points are
near or iur off. Similarly. he point al illerent elevation with respect to a given datum can be
established by leveling
Levelling Instruments: i.. ins1rumei shich are directly used for leveling operation are:
Level. Levelling stafl
Levei: - An instrument which is used ur observ ing statt reading on leveling statf keptover
difierent points after creuting a line o1ght is called a level.
0o The ditlerence in elevation between tiie point then can Worked out. A level essentially consists
O1 the following points:
) Levelling ieads
v<
ag<
Basic Civi Engineering
81d
Department of Civil Engineering
2) Limb plate
3) Telescope
4) Bubble tube
5) Tripod stand
Telescope consists of two tubes, one slide into the other and fitted with lens and diaphragm
havig cross hairs. It creates a line of sight by which the reading on the staff is taken
The essential parts ofa telescope are
1) i50dy 2) object glass 3) Eye-piece 4) Diaphragm 5) Ray shade 6) The rack and pinio
arrangenmcnt 7) Focusing serew 8) Diaphragm serew.
Dunpy level;
The dumpy level is simple. compact and stable instrument. The telescope is rigidly fixed to
ts supporls. Hence it cannot be rotated about its Longitudinal axis or cannot be removed
ils support. The nane dumpy is because of its compact and stable construction. The
fron is
axis of lelescope is perpendicular to the vertical axis of the level. The level tube
but itis
perancntly placed so that its axis lies in the same vertical plane of the telescope
adjustable by means of captain head nv at one end. The ray shade is provided to protect
in modern level to control
the ubject glass. A clamp and slow motion serew are provided
the vencnt of spindle. about the verlical axis. The telescope has magnifying power
of about tirty diameters
has normally a sensitiveness of
The level tube is gradualed to 2nmm divisions and it
be internally focusing or external
20 econds of are per gradeation. The elescope may
Focu ng Iype.
Adju tnent of the level
The level needs two type of adjustmeni
Temporaryadjusipment and
2) Permanent adjusnient
level
Temporary adjustments of dunpy
are performed ai cach set-up the level before taking any observation.
hese adjustments
level:- this incudes
Sctting up the
-
in the the tripod leys are well spread on the
tripod:
) Fixing tlie nstrument
head nearly level and al convenient height. Fix up the
ground w ith tripod
level on iihe tripod.
-
r.ig all the loot screws level in the centre of
tment: of the
2 Leg adju
Department of Civil Engineering
their run Fix any two legs
firmly into the ground by pressing them with
hand and move the tlhird
leg to leg to right or left until the main bubbleis
roughly in the centue.
Finally the
legs are fixed after centering
approxinatcly botlh bubbles. This operation will save the time required
for leveliug.
3) Levelling: Levelling is done with the help of foot serews and bubbles. The
purpose of levelling is to make the vertical axis truly vertical. The method of
leveling the instrulnent depends upon whether there are three foot screws or four
Toot serews. In all modern instruments three foot serews are provided and this
method only is deseribed.
FOOT SCREW=
UNGI TUDINAL BUBBLE
TUBC
1) Place the teleseope parallel to pair of foot screws.
2) Hold these two fuut serew between the thumb and first finger of each
hand ani turn thenm unilormly so that the thumbs move either toward each
other until the bubble is in centre.
3) Turn the telescope lhrough 90°so that it lies over the third foot screw.
4) Turn this fout serew ouly until the bubble is centred.
5) Bring ihe telescope back to its original position without reversing the eye
piece and object glass ends.
6) Again bring the bubble to the centre of its run and repeat these operation
until the bubble remains in the centre of its run in both position which are
at right angle to eacl other.
7) Now rotate the instrument through 180°.the bubble should remain in
centre provided the instrument is in .it needs
adjustment: il not permanent
adjustment.
c)Focusing tie eye picee: - To focus the eye piece, hold i white paper in front of
te object glass. and move tiic cye piece in or oul tull the eross hairs are distinctly
asic Civ ngineering
Department of Civil Engineering
seen. Partieular
graduation position to suit his eyes, this will
tocusing the eye pieee. save much time of
d) Foeusing the -
object glass: Direct the telescope to the
looking througlh the lelescope. lurn the
leveling staff and on
clears and focusing serew until the imuge appears
sharp, The image is thus formed
Parallax, if any is inside the plane of eross hairs,
removed by exact
completely eliminated when focusing, It may be noted that parallax is
there is no
eye up and down. clhange in stalf reading alter
moving the
) Bubble tube
2) Tripod stand
Reduced Levels
The system of working out the reduced
level of the points from stall
the field is called as reading taken in
redieed level (R.L) of points is the elevatin of the
Telerence to the same datum. with point
There are two
systens of reduced levels
)The plane of colimation sy stem (H.l.method)
2) The Rise and tiull
system
) The plane of collimation
system (H.I.method))
ln this sy stem, the R.L. of
plane of collimation (1.I) is found out lor
every set-up
level and then the reduced levels of the
of the
points are
worked out with the
respective plane
ofcollimation as deseribed below.
) Deternine the R.L. oi plane of collimation lor the
lirst set up of the level
by addig B.S. to
the R.L. of B.M. i.e.( R.L of
plane ol eollimation= R.L.
ofB.M. 3.S.)
2) Obtained the R.IL. o the intermediate points and fiusi change point by
subtracting the statî readings (1.S. and F.S. from the R.l.. of
collimaion plane of
(li.i). (RI. of a point=R.L of plane of coliimation H.I.-1.S or
F.S)
3) When the instruneni is shilted and set up at new
posiIOn a new plane of
collimation is deteruuined by addition of B.S. to the s.L of
Thus the levels ironi two set-ups ol the instruments e:an
clhange point.
be correlated by
means orB.S. and S. taken on C.P.
4) Find oui the R.L.s ol the succesSive
pots and tie secord C.P. by
subtracg tlieir stli readings from this plane of colimation R.L
Basic CivErgineeiing
by Lmahao
Department of Civil Engineering
5) Repeal the until all the R.Ls
procedure are worked out.
Observation table:-
Reading R.L. of plane Reduced
Station B.S I.S
Remarks
F.S collimation (1.) Level
sum
Arithmetical check: The diflerenee between the of the back sigl1ts and thc sum of
the lore sights should be to
equal the difference between the last :and icduced levels.
ie =
B.S-F.S. LAST R.L -FIRST R.L
2) The Rise and Tall system
ln this system, there is no need to determine R.L. of
plane of' eollmation .The
dillerenee of level betiween consecutive poinls is obtaned as deser.d below.
1) Determine the dilferenee in staff readings between the conseeutive
points
comparing cach point after the first with that imniediately preceding it.
Obtained the rise or fall fronm the difference of their staff reading accordingly
to the staff reading at tlhe is smaller or lhil of
point greater than proceeding
pOn
2) Find out ilie redueed level of each point by adding tde rise ur
subtracting
fall from he R.l.. uta proceeding point.
3) Observalion table:-
Reading Rise Fall Reducedl
Station 13.S 1.S
Remarks
F.S Level
Basic Civil Engineering
1 Srn
Department of Civil Engineering
Tfesulis are tabulated as below:
B.S. L.S F.S . R.
2.795 Remarks
97.215 100.000 B.M.Staff
inverted
1.500 95.715 Point A
When the reading on the inverted staff is a foresight or intermediate sight. It should also be
Tecorded in lield book witlh minus
sign
The R.L. of such points may be worked at as:
R.I.of the point (wlhere the inverted staff is held) =R.L. of H.I +F.S. or
I.S.reading
RESULT:
The various reduced levels re caleulated by rise and fall method and by usily
height or
plune of collimation method and are shown in observation table.
3.CA)
whatis
levellin in
Survey
Lvellin is
banch of
he elevations of
given
Sunveyiy18 used
poits
sed to
t fmd
fmd
assu SSU withrpect to Jiven
med datum.
) wha+ is
datum in lvellin?
A Datum is CU ImagimaTy
rel surtace DY level line
homhich heyer hical disten
points
ces of diflernt
poimts an een SUtd.
.3) what is Bench Mar k (B-m) im
avellim
evellim
) &m is a la
e nre whose
tively perma ment point ot
elevation with
respect to
assum ed datum s Some
knowm.
9.)whas reduced leve (R-L) m Levelliing2
) The Verhcal distamce of poit a bove or
be low the
datum s kmown as the
OT RL fa
of elevahon
poiyt. it may be ve oT or ve
ve
9-s) wnite down minPasts of evel instrumet ?
Tele Scope *Foot Scztws
ye piece *
Uppev parallel plate
*objeetive lems C TribTach)
Focusimg ScHw Feot plaBt ( Tivet )
Bubble Tube Slow motion Scw
Tipod
