The document discusses the classification and principles of surveying, specifically focusing on levelling, which is the process of determining the relative heights of various points. It covers definitions, instruments used in levelling, types of levelling methods, benchmarks, and common errors encountered during the process. Key topics include different types of levels, levelling staffs, and adjustments necessary for accurate measurements.

1. CLASSIFICATION OF SURVEYING
Mr. Kaviraj M S, Assistant Professor,
Department of Civil Engineering,
Adithya Institute of Technology,
Acdemic Year: 2021-2022

36. Levelling & Contouring

37. Definition, Principle, & Object of
Levelling
Definition:- Levelling is defined as“an art
of determining the relative height of
different points on, aboveorbelowthe
surface”.

38. Principle of
levelling
Principle:- The principle of levelling is to obtain
horizontal line of sight with respectto which
vertical distancesof the points aboveorbelow
this line of sight are found.

39. Object of levelling
Theobjective of levelling is to
1) Findthe elevation of given point with
respectto someassumedreferenceline called
datum.
2)T
oestablish point at requiredelevation
with respectto datum.

41. Definitions used in
levelling
 Levelsurface:- It is the surfaceparallel to
the mean spheroidal surface of the earth
 Levelline:- Linelying onlevel surface.
 Horizontal plane:- Horizontal planethrough
apoint is aplane tangentialto level surface.
 Horizontal line:- It is astraight line
tangential to level line.

42.  Datum:- “Itis an arbitrary level surfacefromwhich
elevation ofpoints maybereferred”.In India meansea
level is consideredasdatum of zeroelevation it is situated
at Karachi.
Meansealevel is the averageheight of seafor all stagesof
tides it is derived by averaging the hourly tide height over
a period of 19 years.
 Elevation or Reduced level:- It is height or depth of
any point above or below any datum. It is denoted as
R.L.

43.  BenchMark(B.M.):- It is a fixed referencepoint of known
elevation with respectto datum.
 Line of collimation:- It is aline joining the intersection of
crosshairs of diaphragmto the optical centreof object
glass and its continuation. It is also knownasline of
sight.
 Height of instrument:- It is the elevation of line
of collimation with respectto datum
 Backsight:- It is astaff reading taken at a known
elevation. It is the first staff reading taken after setup
of instrument.

44.  For
e sight( F
.S.):- It is the last staff reading taken
denoting the shifting of the instrument.
 Intermediate sight.(I.S.):-It is staff reading taken ona
point whoseelevation is to bedetermined.All staff
reading betweenB.S. and F
.S.areIntermediate sight.
 ChangePoint:- It is apoint onwhichboth foreand
back sight are taken.

45. Instruments for
levelling
 The following instruments areessentially
required
 for levelling
 Level
 Levelling staff

46. Level and types of
level
 Level:- The instrument usedtofurnishhorizontal
line of sight forobservingstaff readingsand
determining R.L.s
 T
ypes
 Dumpy level
 Tilting level
 W
ye level
 Automatic level

47. The Dumpy level is a simple,
compact and stable
instrument. The telescopeis rigidly fixed to its supports.
Henceit c
a
n
n
o
tDb
eurmo
t
apt
e
dyalbeo
uvtehlo
r
i
z
o
n
t
a
l
axis.

48. It is alsoknownasI.O.P
.level (Indian officePattern). In
this levelthe telescope tilts about its
horizontal axis henceit is calledTtiillttini
ng
gl
e
vleel vel

49. Wye
level
Theessential differencebetweenwyelevel andotherlevelsis
thatin wyelevel the telescopeis carried bytwovertical wye
supports.The telescopecanberotated, movedorevenraised
in wyes.

50. Automatic
level
It is alsoknownasself aligning level. It is arecent
development.
Thefundamental differencebetweenauto level andotherlevels
is that the levelling is not manually but it is levelled
automatically. It is achievedbyinclination compensating
device.

52. Levelling
Staffs
 Levelling staffs arescalesonwhichthesedistances
are measured.
 Levelling staffs areof two types
 Self reading staff
 T
arget staff

53. Self reading
staff
 The self readingstaff canbereaddirectly bythe
level manlooking through the telescope.
 Commontypes of self reading staffs
 Ordinary staff
 Sopwith telescopic staff
 Folding Staff

54. Target
staff
 For very precise works and sight target staff are used.A
movable target is provided in this staff.A vernier is
provided on target to give precise reading. In target staff
level man directs the staff man to
move the target up and down until it bisects by
the line of sight.The staff man observe the staff
reading

56. Bench
Marks
 Benchmarkis apoint of known elevation
 Thereare4 kinds of bench marks
 GTS(Greattrigonometrically surveybench
mark)
 Permanentbench mark
 Arbitrary bench mark
 T
emporarybench mark

57. GTS Bench
mark
 They are the bench marks established with veryhigh degree
of precisionat regularintervals bythe surveyof India
Department all overthe country Their position andR.Ls
valuesabovemean seallevel at Karachiaregivenin catalogue
formedbythe department.
 Meansealevel

58. Permanent Bench
mark
Permanent bench marksare fixed in between GTS bench marks by
govt. agencies such as railways, PWD,etc. This bench marks are
written on permanent objects such as milestones, culverts,
bridges etc their value are clearly written and their position are
recorded forfuture reference.

59. Arbitrary benchmarks:- Thesearereferencepoints whose
R.L.s arearbitrarily assumed.They areusedin small
works suchbenchmarkmaybeassumedas100. or50 m
T
emporarybenchmarks:- They arethe referencepoints
established during the levelling operationswhenthere is
a breakin work,orat the endof day’
sworkthe value of
reducedlevels aremarkedonsomepermanent objects
such asstones, trees etc.

60. Temporary Adjustments of a
level
 Theseadjustments areperformedat everysetup
of instrument
 Setting up of level
 Levelling of telescope
 Focusingof the eye peace
 Focusingof object glass

61.  Setting up the level:- Thisincludes
 A)Fixing the instrument ontripod
 B)Levelling the instrument approximately byTripod
 Levelling:- LevellingLevelling is donewith the help of foot screws.
The purposeoflevelling is to makevertical axis truly vertical. It is
donewith the help of foot screws
 A)Placethe telescopeparallel to apair of foot screwthen hold
the foot screwsbetweenthumb andfirst finger andturn them
either inwardoroutwarduntil the longitudinal bubblecomesin
the centre.
 B)Turnthe telescopethrough 900 sothat it lies parallel to third foot
screw
,turn the screw until the bubble comes in the centre.

62.  Focusing the eye piece:- T
o focus the eye piece, hold a
white paper in front of object glass, and move the eye
piecein or out till the crosshair aredistinctly seen.
 Focusingof object glass:- Direct the telescopeto the
levelling staff and onlooking through the telescope,
turn the focusing screwtill the imageappearsclearand
sharp.

63. Classification of
levelling
 Simple levelling
 Differential leveling
 Fly levelling
 Check levelling
 Profile levelling
 Cross levelling
 Reciprocal levelling
 Precise levelling
 Trignometric levelling
 Barometric levelling
 Hypersometric
levelling

64. Simple levelling:- It is the simplest methodused, whenit is
requiredto find the difference in elevation between2
points.
Differential Levelling:- This methodis usedto find the
difference in the elevation betweenpoints if they aretoofar
apart orthe difference in elevation betweenthem is too
much.

66. Flylevelling:- Flylevelling is just like differential levelling
carried out to checkthe accuracyoflevelling work.In fly
levelling only B.S.andF
.S.are taken

67.  Checklevelling:- This kind of levelling is carried out to
checkthe accuracyof work.It is doneat the end of the
days workin the formof fly levelling to connectthe
finishing point and starting point.
 Profile levelling orL-Section:-This method is usedfor
taking levels along the centreline of any alignment
like road, railwaycanal etc.The object is to determine
the undulations of the ground surfacealong the
alignment

69.  Cross-sectioning:- This operation is carried out
perpendicular to alignment at an interval of 10,
20 ,30, 40 m.The idea is to makean estimate of
earthwork.
 Preciselevelling:- It is usedforestablishing benchmarks
for future public use. It is carried out with high degreeof
accuracyusing advanced instruments
 Trignometriclevelling:- In this methodvertical
distances betweenpoints arecomputedbyobserving
horizontal distances and vertical angle between
points.

70.  Barometric levelling:- In this method the altitude difference
is determined bymeansof a barometer
.
 Hyposometric levelling:- The working of Hyposometry for
determining the elevation depends upon the fact that the
temperature at which water boils varies with the
atmospheric pressure. The boiling point of water reduces at
higher altitude thus knowing the boiling point of water
,
the atmospheric pressure can be calculated and knowing
the atmospheric pressure altitude or elevation can be
determined

71. Reciprocal
levelling
 Reciprocal levelling:-This method is adopted to accurately
determine the difference of level between two points which are far
apart. It is also used whenit is not possible to setup level in mid way
betweentwo points
 Let A and B be the two points on opposite banks of a river. It is
required to find out the level difference between A&B
 Set up the level very near to Aand take the reading at Aand Blet
the reading be a1 and b1
 Shift the level and set up very near to B and observe Aand B to
get reading a2 and b2
 Let d is the true difference of level between Aand B, and e= error
due to curvature, refrection and imperfect adjustment.

72. b1’
e
b1
 Thus to eliminate the error take an average of the difference
in elevation taken from 2 points
 i.e. from Athe true difference will be =(bb11-’e)-a1
From Bthe difference will be= b2-((aa2-’e)
 Therefore dd=={{(bb11-’a1)+(b2-a‘2)}/2
a1
Line of
collimation
level
Line
A B
Rive
r

73. b2
e
a2’
Line of
collimation
level
Line
a2
A B
Rive
r
 Thus to eliminate the error take an average of the difference in
elevation taken from 2 points
 i.e. from Athe true difference will be=(b1’-e)-
a1
 From Bthe difference will be= b2-(a2’-e)
 Therefore d={(b1-a1)+ (b2-a2)}/2

74. Methods of Reducing
levels
Height ofInstrumentMethod:-This methodconsist of
finding H.I. foreverysetup of instrument, and then
obtaining the R.L. of point of referencewith respectto
H.I

75. Station B.S I.S F
.S H.I R.L Remark
A 0.9 100.9 100.00 B.M
B 1.1 99.800
C 1.450 1.05 101.3 99.850 C.P
.
D 1.550 99.750
F.S=1.55
m
A100
m
I.S
B
9
91..
18m
m
F
.
S1.05m B.S 1.45m
C 99.85
m
D 99.750
m
B.S 0.9m
B.
M
100
M.
H
I
C .P
.

76. This methodconsist of determining the difference
of
level betweenconsecutivepoints bycomparingeach
point w
i
tRhiismem
e
dai
ant
edp
rfeac
eldli
nmg
peo
itnht
.o
d

77. Rise And Fall
Method
Station B.S I.S F
.S Rise Fall R.L Remark
A 0.9 100.00 B.M
B 1.1 0.2 99.800
C 1.450 1.05 0.05 99.850 C.P
.
D 1.550 0.1 99.750
F
.S
1.05m
B.S
1.45m
F.S=1.55
m
A100
m
I.S 1.1m
B
99.8m C 99.85
m
B.S 0.9m
B.
M
100
M. D 99.750
m
C .P
.

78. Exampl
e
The followingstaff readingswere observed successively with
a level the instrument is moved by third sixth and eighth
readings.
 : 2.228 :1.606 :0.988 :2.090 :2.864 :1.262 0.602 :1.982
:1.044 :2.684 m enter the reading in record book and
calculate R.L. if the first reading was taken at a B.M
of 432.383m

79. H.I.
Method
Station B.S I.S F
.S HI RL REMAR
KS
1 2.228 434.612 432.384 M B.M.
2 1.606 433.006
3 2.090 0.988 435.714 433.624 3RD C.P
.
4 2.864 432.850
5 0.602 1.262 435.054 434.452 6TH C.P
6 1.044 1.982 434.116 433.072 8TH C.P
7 2.684 431.432
5.964 6.916
CHECK ∑ B.S- ∑ F.S= 5.964-6.916= -
0.952
= LASTR.L- FIRSTR.L= 431.432-432.384=-
0.952

80. Rise and fall
method
Station B.S I.S F
.S Rise Fall RL REMARKS
1 2.228 432.384 M B.M.
2 1.606 0.622 433.006
3 2.090 0.988 0.618 433.624 3RD C.P
.
4 2.864 0.774 432.850
5 0.602 1.262 1.602 434.452 6TH C.P
6 1.044 1.982 1.38 433.072 8TH C.P
7 2.684 1.64 431.432
5.964 6.916
CHECK ∑ B.S- ∑ F.S= 5.964-6.916= -0.952 =
LASTR.L- FIRSTR.L= 431.432-432.384=-
0.952
∑RISE- ∑ FALL= 2.842-3.794=-0.952

81. Contou
r
100
105 110
120
Acontour is animaginary line joining points of
equal elevation

82. Contour
Interval
The vertical distance betweenany twoconsecutive
contoursis knownascontour interval
Contour interval

83. Characteristics of contour
lines
 Aseriesof contourlines with higher value
inside indicate a hill
 Aseriesof contourlines with lowervalue inside the
loop alwaysindicate depression
 Closecontour linesindicate steep slope
 Widecontour linesindicate flatter slope
 Contourlines nevercrosseachother exceptin case
of overhanging cliff.
 All points ona contourlines haveequal elevation

85. Uses of
Contours
 Thenature of ground surfaceof aregion canbe
known
 Contourmaphelps in locating propersite for
bridges, dams,reservoirs etc.
 Capacity of areservoircanbecalculated with the
help of contour map
 The quantity of cutting and filling canbe
determined fromcontour maps.
 Routes forroads,railways,canalsetc canbe traced.

86. Errors in
Levelling
Thefollowingarethe different sourcesof Errors
 Personal Error
 The Instruments maynot be leveled
 The focusingof eyepieceand objectiveglassmaynot
be perfect
 Theparallax maynot be eliminated
 The position of staff mayhave changed
 Entry andrecordingin the field bookmaynot be
correct
 The staff maynot befully extended, maynot be
held vertical.

87.  Instrumental Error:
The Permanent adjustment of the instrument may
not be perfect. That is the line of collimation may
not be horizontal line
The internal arrangement of focusing tube may
not be correct
The graduation of the staff may not be perfect

88.  Errors due to Natural Causes:
TheCurvature of the Earth may affect the
staff readings when the distance of sight is long.
The effect of refraction may cause a wrong staff
reading
There are some errors in staff readings
due to high velocity wind.

89. Curvature
Correction
 For long sights the curvature of earth can effect staff
readings. The line of sight is horizontal but the level line is
curved and parallel to the mean spheroidal surface of the
earth. The vertical distance between the line of sight and
level line at particular place is called the curvature
correction
 The effect of curvature is to cause the object sighted to
appear lower than they really are.
 Curvature correction is always Subtractive (-)
 True staff reading= (Observed staff reading- 0.0785 D2) m
 Where D= distance in Km.

90. Curvature
Correction
(-)
Curvatur
e effect

91. Refraction
 The ray of light pass through layers of air of different
densities and refract or bent down. The effect of refraction is
to make the object appear higher then they really are.
Refraction varies considerably with climate conditions.
 However it is taken as
Cr= 0.0112 D2m (+)
 Refraction is always additive
 True staff reading= Observed staff reading + Refraction
correction.

92. Refraction
(+)
Refraction
effect

93. GPS Surveying
GPS -- how it works
GPS -- Garmin 12

94. The Garmin 12
GPS
Change
windows
Get back to a point
Use to scroll and for keying
Confirm
TURN ON

96. Trilateration and a 4th for timing

97. First page up….
4 important
pieces of data
The satillite
It’s signal
Nav
Error

98. Once you
have a
fix
Are you late?
Where you are
Your elevation
(flaky)
Are you
moving?

99. Getting back
to where you
started
Hit GOTO
Pick a Waypoint
Follow the
arrow Monitor
Speed Check
Distance

100. GPS Accuracy
Non-corrected 5-30
m
Beacon-corrected
1 m Radio-corrected
cms Post-processed dm

101. Differential GPS for precision
surveying of river terraces and
alluvial fans

102. Crash Course in Surveying With
an Auto Level:

103. :
(
(
1
First thing first: Gotta level the
it

104. CENTERLINE - ELEV
ATION 
BOTTOM = DISTANCE
TOP= DISTANCE
1

105. 1
The Auto
Level:
The
Instrument
And Tripod
The Stadia Rod
Or Surveyor’s
Staff
= l (m) * 100
(m)

106. How to read the Stadia
Rod:
11 meters on the
dot
10.8 meters on the
dot
Each Black
Rectangle
= 1 cm
Same for
Each
white one
So what’s
this height?
10.66 meters

107. What you’ll see through the
eyepiece:
Stadia
Lines
Height = 10.85
m
Top Stadia = 10.91
m
Bottom Stadia = 10.79
m
To Get Distance Away:
1) (Top - Bottom Stadia) = 0.12 m
2) Multiply difference by 100: Distance = 12 meters

108. 1
For your X-section, be sure to get
any Major changes in slope
Distance
Heigh
t
(X,Y)

109. How to collect the
data:
NOTE:When shooting features off your line, you
will also need a bearing

111. ?

112. Side-Scan LiDAR:
GeoArcheology

114. “Project North” is at the white
house, And that is BM1
Figure out appropriate scale for x:
1 box = 1 meter? 10 meters? Y
ouwant your entire survey to
fit!
Same
scale
as
x-
axis
BM
1
BM
2
BM 4
PN
BM 3