Question

The radius of a horizontal circular curve on a highway is 120 m. The design speed is 60 km/hour, and the design coefficient of lateral friction between the tyre and the road surface is 0.15. The estimated value of superelevation required (if full lateral friction is assumed to develop), and the value of coefficient of friction needed (if no superelevation is provided) will, respectively be

Answer 1

Given R = 120 m, V = 60 kmph and f = 0.15

$\Rightarrow e+f=\frac{V^2}{127R}$

$\Rightarrow e+0.15=\frac{{60}^2}{127\times 120}$

$\Rightarrow e=\frac{1}{11.6}$

Also, if e = 0

$\Rightarrow f=\frac{V^2}{127R}=\frac{{60}^2}{127\times 120}\simeq 0.24$