Question

Which of the following advantages are correct regarding Poly-centric shape tunnel?

1. It can be conveniently used for road and railway traffic

2. The number of centres and lengths of radii cannot be fixed

3. It can resist external and internal pressure due to its arch action
1. 1 and 2 only
2. 2 and 3 only
3. 1 and 3 only
4. 1, 2 and 3

Answer 1

Correct Answer - Option 3 : 1 and 3 only

Poly-centric Tunnel:

1. This tunnel section consist number of centres.

2. The base of tunnel is flat enough for traffic, hence can be used for radius and railways.

3. The number of centres and length of roads can be fixed as per the local conditions hence required greater skilled persons.

4. The tunnel can resist effectively external and internal pressure for their arch shape.

5. Disadvantages: Their construction and lining is very difficult.