MEHODS OF TRAVERSING
Traverse survey may be conducted by the
following methods :
following methods :
1.
Chain
traversing (by chain angle)
Chain
traversing (by chain angle)
2.
Compass
traversing (by free needle)
Compass
traversing (by free needle)
3.
Theodolite
traversing (by fast needle) and
Theodolite
traversing (by fast needle) and
4.
Plane
table traversing (by plane table)
Plane
table traversing (by plane table)
1.Chain traversing Chain traversing is mainly conducted when
it is not possible to adopt triangulation. In this method, the angles
between adjacent sides are fixed by chain angles. The entire survey is
conducted by chain and tape only and no angular measurements are taken. When it
is not possible to form triangles, as, for example, in a pond, chain traversing
is conducted,
it is not possible to adopt triangulation. In this method, the angles
between adjacent sides are fixed by chain angles. The entire survey is
conducted by chain and tape only and no angular measurements are taken. When it
is not possible to form triangles, as, for example, in a pond, chain traversing
is conducted,
The formation of chain angles is
(a) First Method Suppose a chain
angle is to be formed to fix the directions of sides AB and AD. Tie
stations T1 and T2 are fixed on lines AB and AD. The
distances AT1, AT2 and
T1T2 are
measured. Then the angle T1AT2 is said to be the chain angle. So, the chain
angle is fixed by the tie line T1T2.
angle is to be formed to fix the directions of sides AB and AD. Tie
stations T1 and T2 are fixed on lines AB and AD. The
distances AT1, AT2 and
T1T2 are
measured. Then the angle T1AT2 is said to be the chain angle. So, the chain
angle is fixed by the tie line T1T2.
(b) Second Method Sometimes the chain
angle is fixed by chord. Suppose the angle between the lines AB and AC is to be
fixed. Taking A as the centre and a radius equal to one tape length (15 m), an
arc intersecting the lines AB and AC at points P and Q, respectively, is
drawn. The chord PQ is measured and bisected at R.
angle is fixed by chord. Suppose the angle between the lines AB and AC is to be
fixed. Taking A as the centre and a radius equal to one tape length (15 m), an
arc intersecting the lines AB and AC at points P and Q, respectively, is
drawn. The chord PQ is measured and bisected at R.