Concept: Extra widening of road is given by, We=Wm+Wps W=nl22R+
V
9.5√R
We = where, Wm = mechanical widening Wps = psychological widening n = No. of lanes l = length of wheel base R= radius of curve V= velocity of vehicle (kmph) Calculation: Given, n = 2 l = 5 m R = 250 m V = 70 km/h Wm = 2× ( 52 ) / (2 × 250) = 0.1 m