Question

While doing the levelling process on a steep slope, the instrument should preferably be set up successively along a: 
1. Triangular path   
2. Curved path 
3. Zig-zag path   
4. Straight path

Answer 1

Correct Answer - Option 3 : Zig-zag path   

Explanation

Difficulties in Levelling

Leveling across a hill

• The instrument should be set on one side of the hill rather than on the top. Such a setup saves time.

Leveling across a hollow

• Set up the instrument sufficiently low to enable the levels of the hollow to be obtained. Also setting up the instrument to one side of the hollow saves time.

Leveling on a steep slope

• To equalize BS and FS distances, take the instrument along a zigzag route. To keep the staff vertical, use a plumb bob or a circular level.

Leveling across a pond

• The surface of still water is a level surface. The RL of the water surface could be determined from one side and the leveling can be continued from the other side of the pond. Alternatively, reciprocal leveling could be done.

Leveling across a high wall

• The RL of the top of the wall is determined and the leveling continued from the other side of the wall