Geometric Design MCQ with answer and solution

Concept

Minimum superelevation criteria for road drainage

Formula

e_min = Camber

Step-by-step solution

1. Superelevation is calculated based on design speed and curve radius (e = v² / (225R)). 2. If this value is smaller than the road's cross-slope (camber), water drainage across the outer edge could be impeded. 3. IRC specifies that minimum superelevation must not be less than the camber slope. 4. Hence, the minimum superelevation required is equal to camber. Answer: D

Explanation

According to IRC specifications, if the calculated superelevation on a horizontal curve is less than the camber rate of the road, the minimum superelevation provided should be equal to the camber of the road surface to ensure efficient cross-drainage.

Why the other options are wrong

A) 10% is the maximum superelevation for hilly roads without snow bound conditions. B) 7% is the maximum superelevation for plain and rolling terrain. C) 4% is the maximum superelevation for urban roads with frequent intersections.

Shortcut

Calculated e < Camber -> Provide e = Camber.

Common mistake

Selecting 7% (max superelevation for plain terrain) or 4% (for urban areas) instead of understanding minimum drainage slope requirement.