Explain the Stopping Sight Distance
Stopping Sight Distance Is the Sum of Two Distances
(1) The distance traversed by the vehicle from the instant the driver sights an object necessitating a stop to the instant the brakes are applied; and
(2) The distance needed to stop the vehicle from the instant the brake application begins.
These are referred to as brake reaction distance and braking distance, respectively.
SSD = 1.47Vmpht + V2mph / 30 ((a/32.2) + G)
Where:
SSD = Stopping Sight Distance, ft;
V = design speed, mph;
t = breaking reaction time, 2.5 sec2
a = deceleration rate, 11.2 ft/sec
G = percent of grade divided by 100, it is in decimal
First part of the equation represents brake reaction distance and the second part represent braking distance.