# How To Calculated Superelevation || Mathematical Example

5th April 2019## 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

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,

- Amount of superelevation for 7.5m wide road = 0.06 ⨯ 7.5 =0.45m
- Equilibrium superelevation (e) = V² /127R = 80² /127 ⨯ 240 = 0.21 = 1 in 4.75

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