Find Headlight And Intermediate Sight Distance

Here, a mathematical problem is taken to determine the value of headlight sight distance and intermediate sight distance, when the value of the design speed is given.

Mathematical Problem

Find headlight sight distance and intermediate sight distance for a design speed of 65 Km/h (Use f=0.36, t=2.5 sec)

Mathematical Solution

Design speed = 65 Km/h = 18 m/sec

Now,

Stopping Sight Distance (SSD) =( vt + v²/2gf ) = 18⨯2.5+ 18²/(2⨯9.81⨯0.36) = 91m.

Another way, when design speed is taken as 65 Km/h.

SSD = (0.278V.t + V²/254f) = 0.278⨯65⨯2.5 + 65²/254⨯0.36 = 91m so,

Headlight Sight Distance(HSD) = SSD = 91m
Intermediate Sight Distance(ISD) = 2(SSD) =2⨯91=182m