# 6 Stopping Sight Distance Formula

The stopping sight distance formula, based on the road surface condition and speed of the vehicle units(m/sec or km/h) is divided into 6 types:

## A. Level Surface With Friction Coefficient

Stopping Sight distance formula(SSD) for level surface with a coefficient of friction:

1. SSD = Vt + V

**/2gf (when V in m/sec).**^{2}2. SSD = 0.278 Vt + V

**/254f (when V in km/h).**^{2}## B. Inclined Surface with Coefficient of Friction

Stopping Sight distance formula(SSD) for inclined surface with a coefficient of friction. Where ‘n’ % gradient.

1. SSD = Vt + V

**/2g(f ± 0.01n) when V in m/sec.**^{2}2. SSD = 0.278Vt + V

**/254(f ± 0.01n) when V in km/h**^{2}Where ‘n’ % gradient and + sign for ascending gradient, – sign for descending gradient.

## C. Level Surface With Braking Efficiency

Stopping Sight distance formula(SSD) for level surface with braking efficiency η.

1. SSD = Vt + V

**/2gfη where V in m/sec.**^{2}2. SSD = Vt + V

**/254fη where V in km/h.**^{2}