How To Calculated Superelevation || Mathematical Example - Civil Engineering

How To Calculated Superelevation- Mathematical Example

Here one mathematical example of superelevation is given below and showing how to determine superelevation.

Mathematical Example

Calculate the superelevation required for a road 7.5m wide on a curve of 240m radius for a permissible speed of 80 Km/h. Assume the coefficient of lateral friction as 0.15. Also, calculate the equilibrium superelevation for the condition when the pressure on the inner and outer wheel will be equal.

Mathematical Solution of Superelevation

Given,
• Road Width(b) = 7.5m
• Radius of curve(R) = 240m
• Permissible speed(V) = 80 Km/h
• Coefficient of lateral friction(f) = 0.15
We know, e + f = V² /127R
Where e = Rate of superelevation
Therefore, e + 0.15 = 80² /127 ⨯ 240
or, e = 0.06 = 1 in 16.67
Now,
1. Amount of superelevation for 7.5m wide road = 0.06 ⨯ 7.5 =0.45m
2. Equilibrium superelevation (e) = V² /127R = 80² /127 ⨯ 240 = 0.21 = 1 in 4.75