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 + V2/2gf (when V in m/sec).
2. SSD = 0.278 Vt + V2/254f (when V in km/h).
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 + V2/2g(f ± 0.01n) when V in m/sec.
2. SSD = 0.278Vt + V2/254(f ± 0.01n) when V in km/h
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 + V2/2gfη where V in m/sec.
2. SSD = Vt + V2/254fη where V in km/h.