Question

The rate of super-elevation for a horizontal curve of radius 400 m in a national highway for a design speed of 80 kmph is _______

• A. 0.07

Answer 1

The correct option is A 0.07

Design super elevation is done for mixed traffic condition
$e=\frac{V^2}{225R}=\frac{{80}^2}{225\times 400}=0.071>0.07$

Check for lateral friction

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

$\Rightarrow 0.07+f=\frac{{80}^2}{127\times 400}$

$\Rightarrow f=0.055<0.15$

Hence OK

So, provide
$e=0.07$