# Stopping Or Non Passing Or Headlight Sight Distance

## Stopping Or Non-Passing Or Headlight Sight Distance

Stopping or non-passing or headlight sight distance is the distance required by a driver of a vehicle travelling at a given speed to bring his vehicle to a stop after an object of the road become visible. It is made of two components:

i) The distance travelled during the total reaction time i.e. the lag distance.
ii) Breaking distance

Therefore ,Stopping sight distance(Non Passing Or Headlight Sight Distance) = Lag distance + Breaking distance(in m)
= 0.278 Vt + V2/254f  .

When there is an ascending gradient (+ n %) or descending gradient (- n %),the above equation becomes:

Stopping Sight Distance(Non Passing Or Head Light Sight Distance) = 0.278 Vt + V2/254(f ± 0.01n) .

On roads with restricted width or on single-lane roads when two-way traffic movement is permitted then minimum stopping sight distance should be equal to the twice the stopping sight distance calculated above.