Correct Answer - Option 4 : 1 in 30
Explanation:
Gradient: Gradient is the rate of rise or falls along the length of the road with respect to horizontal.
Expressed as ‘1' vertical unit to 'N' horizontal units.
Types of Gradient:
i) Ruling gradient: The gradient is fixed in such a way that maximum power developed by the engine is equal to the power required to overcome the resistance to the motion on the grade at design speeds.
ii) Limiting gradient: A gradient steeper than the ruling gradient which may be used in restricted length, where the ruling gradient is not possible.
iii) Exceptional gradient: A gradient steeper than the limiting gradient which may be used in very short stretchers only in an exceptional case.
Terrain
|
Ruling
|
Limiting
|
Exceptional
|
Plain/Rolling
|
3.3
|
5.0
|
6.7
|
Hilly
|
5.0
|
6.0
|
7.0
|
Steep
|
6.0
|
7.0
|
8.0
|
∴ The value of the ruling gradient in plains as per IRC is 1 in 30 or 3.3%.