This file contains an obstacle chain survey- obstacle is basically of 3 type obstacle in chaining but not in ranging, an obstacle in range but not in changing and obstacle in both.

1. Alok Sharma

2.  Obstacle to ranging (Vision obstacle)
 Obstacle to Chaining
 Obstacle to both

3.  A hill is an obstacle to ranging but not
chaining.

4.  A pond is obstacle in chaining but not in
ranging.

5.  Building are obstacle in both ranging as well
as chaining.

6.  The principle of chain surveying is triangulation.
This means that the area to be surveyed is
divided into a number of small triangles which
should be well conditioned. In chain surveying
the sides of the triangles which should be well
conditioned. In chain surveying the sides of the
triangles are measured directly on the field by
chain or tape, and no angular measurements are
taken. Here, the tie lines and check lines control
the accuracy of work.

7.  Survey stations
 Main survey line
 Base line
 Tie line
 Check line
 Well condition trinagle
 Chainage
 Offsets

8.  Closed traverse
 Open traverse

9. True meridian-
True meridian is defined as the plane that
passes through true north
poles (geographical north pole) and true
south poles (geographical South Pole) at the
place of observation.True meridian can be
established by astronomical observation as it
passes through true north and south.

10.  When the magnetic needle freely suspended
and balance properly in the atmosphere,
unaffected by atmosphere and magnetic
substance, it shows north and south
direction. Called magnetic meradian.

12.  True bearing- Angle through true north and
true south.
 Magnetic bearing- Angle through magnetic
north and south.
 Arbitrary bearing- Angle through arbitrary
Line.

13.  Whole circle bearing- angle up to 360 D ,
Angle always calculated through N
 Quadrantel bearing or Reduce bearing-
 Angle 0 to 90 D.
 Angle calculated through north or south.

14.  lFB-BBl=180