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 on the road becomes 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 the minimum stopping sight distance should be equal to twice the stopping sight distance calculated above.