Question

What will be the length of transition curve required on a horizontal curve of radius 500 m on a highway passing through rolling terrain for a design speed of 80 kmph? (Answer correct upto one decimal place)

Answer 1

R = 500 m, V = 80 kmph

Length of transition curve as per:

(a) Rate of change of centrifugal acceleration criterion
$L=\frac{V^3}{CR}$
where,
$C=\frac{80}{75+V}=\frac{80}{75+80}$
$=0.516m/s^3$
$\therefore L=\frac{(80\times 5/18{)}^3}{0.516\times 500}=42.54m$

(b) As per IRC guidelines
$L=2.7\frac{V^2}{R}\text{(For plain/rolling terrain)}$
$=2.7\times \frac{{80}^2}{500}=34.56m$
$\therefore L=42.54m$