This document describes leveling, which is a surveying method used to determine elevation differences between points. It defines key leveling terms like benchmark, backsight, foresight, and introduces two common leveling booking methods - height of instrument and rise and fall. Height of instrument determines elevations by adding/subtracting staff readings to the known elevation or last benchmark. Rise and fall codes elevations increases as rises and decreases as falls to track changes in elevation from one point to the next. The document provides examples of how to record leveling data and compute elevations using each method.

1. CHAPTER THREE
VERTICAL DISTANCEMEASUREMENT( LEVELING)
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Content :-
Introduction
Definitions of Basic Terms
Principle of leveling
The Leveling Instrument
Booking Methods of Leveling and Reduction of
Levels
Types of Leveling
Errors in leveling
Engineering application of leveling

2. 3.1 Introduction
 Leveling is a method of surveying used for determination
of the difference of elevations or
 Levels of various points on the surface of the earth.
The elevation of a point is its vertical distance above or
below a reference level, called datum.
The most commonly used datum is the mean sea Level
(M.S.L)
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3. Leveling is an important
 for many engineering works and
construction projects.
 Leveling is needed for the design of highways,
railways, and canals e.t.c and for locating the gradient
lines.
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4. Definitions of Basic Terms
Vertical line: is a line from the surface of the
earth to the earth's center.
Horizontal line: is a straight line perpendicular to
a vertical line.
Mean sea level (MSL): The average height of the
sea's surface for all stages of the tide over a
specified
Vertical control: A series of benchmarks or other
points of known elevation established throughout
an area,
Reduced level (RL): The RL of a point is its
height above or below a reference datum.
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5. 5

6. 3.2 Definitions of Basic Terms
1.Station.The station is the point where the staff is held for taking reading
(observation) from a leveling instrument.
2. Bench mark (BM): -is a permanent or semi permanent point of known
elevation that provides beginning point for determining the elevation of
other points.
3.Height of the instrument. (H.I). It is the elevation of the line of sight
with respect to the datum.
The elevation of the line of sight of the telescope
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7. 4.Backsight (BS) - It is the reading taken
on a staff held at point of known elevation or
 at the point whose elevation has already been determined.
The reading taken after setting the instrument set up(the first reading)
5.Foresight (FS) - The last sight taken before the instrument is moved
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Definitions of Basic Terms …

8. 6.Intermediate sight (IS) - It is the reading taken on a staff held
at point whose elevations is required,
Any sighting that is not a back sight or fore sight
7. Line of Collimation – Imaginary line that passes through
leveling instrument at Cross-Hairs .
8.Turning point. (T.P.) :-For leveling over a long distance, the
instrument has to be set up a number of times.
• A turning point is the point selected on the route before
shifting the instrument.
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Definitions of Basic Terms …

9. 9

10. 9. Balancing of sight. To reduce the effect of
instrumental and other errors, the distance of the point
where a back sight is taken and the distance of the point
where a fore sight is taken, as measured from the
instrument station, should be approximately equal.
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11. 2.Steps in leveling
1. When the leveling instrument has been properly
leveled, the bubble tube axis and the line of sight are
horizontal and the vertical axis of the instrument is
truly vertical.
2. In practice, the leveling instrument is set up at a
convenient position, and the one staff is kept at a
point of known elevation.
3. The reading is taken on the staff and the level of the
line of sight is determined.
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12. 4. Now the 2nd staff is kept on the point of the
unknown elevation and a reading is taken.
5. The level of the point is determined from the level
of the line of sight already computed and from the
2nd staff reading.
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13. 2.Principle of direct leveling
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14. The Leveling Instrument
The Level
 dumpy levels, tilting levels, and automatic levels
Has a set of cross-hairs
 Can be turned through 360° horizontally
 Consist of a high-powered telescope
 Attached to a spirit or bubble level that keeps the line of sight of the
telescope horizontal
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15.  The Tripod:- A fully adjustable 3-legged stand on which
the level sits.
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16. The Staff
 A measuring stick, usually 4m tall, and clearly marked in
divisions of 10mm.
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17. Reading the E Staff
• Each “E” is 50mm
• Each Part of the E is 10mm
• Millimeters are interpolated
• Staff is read to the millimeter
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18. Bubble
 Keep the staff upright
 Any tilt will disturb your readings
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19.  Methods of booking and reduction of Levels
(1)Height of Instrument (HI) method :-
The desired elevation of a point is found by:-
I. adding BS in to given benchmark to find height of
instrument
II. subtracting FS from height of instrument Or
RL of a point = ( RLBM +BS) – FS) = HI – FS
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20. Computation of Elevations
Booking Methods
1.Height of Instrument (HI) method
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21. 1.Height of Instrument (HI) method
station BS IS FS HI Elevation Remar
k
A EleA
a
b
B T.P
c
C
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S1
S2
S3
S4
S5
56
S7
H.IA=EleA+S1
Ha=H.IA-S2
Hb=H.IA-S3
HB=H.IA-S4
Hc=H.IB-S7
H.IB=EleB+S5
Hc=H.IB-S6
Σ B.S. Σ F.S.
Check: Σ B.S. – Σ F.S. = Last R.L. – First R.L.

22. • Let as done the next example
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23. Elevation 100.00
BS
12.64
FS
3.11
Stn
BM1
TP1
Elevn/R.L
BS FS HI
TP1
BM1
12.64 112.64
3.11 109.53
BS
10.88
10.88 120.41
FS
2.56
TP2
2.56
TP2 117.85
BS
9.72
9.72 127.57
BM2
FS
3.10
BM2 3.10 124.47
100.00
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1. BS + Elevation = HI
2. HI - FS = New Elev
1.Height of Instrument (HI) method

24. Change in elevation:
summation of the BS and the FS then subtract
+33.24 -8.77
Change in elevation = 33.24 -8.77 = 24.47
Point
BM1
TP1
Elevation
BS FS HI
12.64 112.64
3.11 109.53
10.88 120.41
2.56
TP2 117.85
9.72 127.57
BM2
3.10 124.47
100.00
ΣΔh = BM2Elev – BM1elev
= ΣBS – ΣFS
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25. Computation of Elevations
Example:-by Using The Following Figure
A. Prepare The Field Book
B. Fill The Staff Reading
C. Calculate The Elevations Of Points TP1 And TP2?
BS
1.27
FS
4.91
TP1
BM
BS
2.33
FS
6.17
TP2
Elevation 356.68
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26. 2.Rise and Fall Method
Rise and fall (RF) method: –
 If 2nd red reading > first rod reading ⇒ fall
 If 2nd rod reading < first rod reading ⇒ rise
 Then RL of 2nd station = RL of first station - fall or
RL of first station + rise
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27. Rise and fall method
Station B.S I.S F.S (+)Rise (-)Fall Elev Remarak
A hA
a
b
B
c
C
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S1
S2
S3
S4
S5
S6
r1=S1 – S2
f2 = S3 – S4
f1=s2-s3
f3 = S5 – S6
r2=S6-S7
ha+=hA + r1
hb = ha – f1
hB = hb – f2
hc = hB – f3
hC = hc + r2
(b) For the rise and fall method
Check:-Σ B.S. – Σ F.S. = Σ Rise – Σ Fall = Last R.L. – First
R.L.
S7
Σ B.S. Σ F.S Σ Rise Σ Fall

28. RISE AND FALL METHOD
Station B.S I.S F.S Rise(+) Fall(-) Elev(R.L Remarke
1 2.390 31.517 BM
2 1.985
3 1.318
4 0.988 1.612
5 1.502
6 1.415
7 2.420 0.316
8 0.532 TBM
Σ=5.798 Σ=2.46
0
Σ=4.146 Σ=0.808
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NOTE:- (+) donates rise and (-) fall

29. RISE AND FALL METHOD
Station B.S I.S F.S Rise(+) Fall(-) Elev(R.L Remarke
1 2.390 31.517 BM
2 1.985 0.405 31.922
3 1.318 0.667 32.589
4 0.988 1.612 0.294 32.295
5 1.502 0.514 31.781
6 1.415 0.087 31.868
7 2.420 0.316 1.099 32.967
8 0.532 1.888 34.855 TBM
Σ=5.798 Σ=2.46
0
Σ=4.146 Σ=0.808
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NOTE:- (+) donates rise and (-) fall