The design speed of the Road is 60 kmph. Assume Reaction time of the driver as 2.5 sec and Co-efficient of friction as 0.6. Brake efficiency is 50%.

Given data:

V = 60 Kmph

t = 2.5 seconds

f = 0.6 and brake efficiency is 50%

As the brake efficiency is 50% the wheels will skid through 50% of the braking distance and rotate through the remaining distance. Therefore, the value of coefficient of friction developed (f) may be taken as 50% of the coefficient of friction,

i.e. f = (50/100) x 0.6 = 0.3

SSD = 0.278 V t + ( V² / 254 f)

= (0.278 x 60 x 2.5 ) + ( 60²/ ( 254 x 0.3))

= 41.70 + 47.24

SSD = 88.94 m. for one way traffic.

SSD for Two Way traffic on single lane road = 2 x SSD for one way traffic

= 2 x 88.94 m

= 177.88 m say 178 m.