survey levelling

1. 1

2. The process of establishing
intermediate point on a
straight line between two
end points is known as
ranging.”
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3. There are two types of ranging:
1. Direct ranging
2. Indirect ranging
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4. Ranging if the points are inter visible
A P Q R B
S
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Direct ranging is done when the two ends of
the survey lines are inter visible. In such
cases , ranging can be done by eye or
through some optical instrument such as
theodolite etc.

5. Ranging when points are not visible
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6. 1. Linear measurements
2. Angular measurements
Linear measurements are further classified as
follows:
i) Horizontal Distance
ii) Vertical Distance
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7. • A horizontal distance is measured in
horizontal plane.
• If a distance is measured along a slope, it
is reduced to its horizontal equivalent
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8. There are two methods for determining horizontal
distance on sloping ground.
1. Direct Method
2. Indirect Method
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9.  This method is also known as “Stepping Method”.
 The horizontal distances are directly measured by the
process of stepping.
 Horizontal distance PQ = S1 + S2 + S3 + S4 + S5
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10.  In this method, the sloping side is measured on the
ground and later it is converted into the horizontal
equivalent.
The following methods are adopted for
calculating horizontal distance indirectly:
i) By measuring angle of inclination
ii)By measuring difference of levels
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11. 2
2
h
L
D 

A
B
C
α
D
L
h
D = L . Cosα
ii)By measuring difference of levels
(Distance along the slope and the
difference in elevation between A and
B are measured.)
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12.  A triangle is a simple figure which can be
plotted from the lengths of three sides
even if the angles
are not known.
 In chain survey, the area to be surveyed is
divided into a framework consisting of
triangles.
 For good results in plotting, equilateral
triangles(as nearly as possible) are
preferred.
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13. The principle of chain survey is chain triangulation.
Survey station:
 It is a prominent point on the survey line and can be
either at beginning or end of chain line
 It is marked on the ground by driving pegs, if ground is
soft.
 If the surface is hard like roads, survey station can be
marked with reference to 2 or 3 permanent objects near
the station.
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14.  Main survey lines:- Lines joining the main survey
stations are called main survey lines.
 Base line:-The biggest of the main survey line is
called base line.
 Check line:- Check lines or proof lines are run in
the field to check the accuracy of the work.
A,B,F & C = main survey stations
AB = base line
DC & EF = Check line
A
B
C
D
E
F
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15.  https://youtu.be/x8FaSZCPbM8
 https://youtu.be/9gs-mnpla3Y
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