# What should be the actual ruling gradient if the ruling gradient of 1 in 200 is accompanied by a curve of 3° at B. G. section?

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What should be the actual ruling gradient if the ruling gradient of 1 in 200 is accompanied by a curve of 3° at B. G. section?
1. 0.5%
2. 0.44%
3. 0.38%
4. 0.41%

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Correct Answer - Option 3 : 0.38%

Concept:

The ruling gradient is the maximum gradient on a particular section, but if a curve lies on a ruling gradient, the resistance due to gradient is increased by that due to curvature, and this further increases the resistance beyond the ruling gradient. In order to avoid resistances beyond the allowable limits, the gradients are reduced on curves, and this reduction is known as the grade compensation for the curve.

Grade compensation (GC) for BG = 0.04% per degree of curve
Grade compensation (GC) for MG = 0.03% per degree of curve
Grade compensation (GC) for NG = 0.02% per degree of curve

Calculation

Given,

Degree of curve D = 4°

Ruling Gradient = 1/200 × 100 = 0.5 %

So for 3° curve, compensation,

= 0.04 × 3 = 0.12%

Compensated gradient = 0.5 - 0.12 = 0.38 %