Question

For MG track standard specifications, concrete sleepers, wherever provided, should have a minimum ballast cushion of:
1. 250 mm
2. 300 mm
3. 200 mm
4. 400 mm

Answer 1

Correct Answer - Option 3 : 200 mm

Concepts:

Ballast is the granular material which is placed and packed below and surrounding the sleeper such that it transmits the load from sleepers to subgrade and also provide good drainage.

The depth of ballast for different type tracks is:

For BG- 20-25 cm

For MG- 15-20 cm

For NG- 15 cm

Therefore, for MG track, depth of ballast cushion is 200 mm.

Additional Information:

1. The minimum depth of Ballast can be calculated as:

D = (S-w)/2

Where,

S = spacing between Sleepers

W = width of sleeper

2. The size of ballast depends on type of sleeper and location of track and its is given as:

For Wooden sleeper- 5 cm

For Metal sleeper- 4 cm

For turnouts and cross-over- 2.5 cm