How To Calculate Minimum Non Passing Sight Distance -Mathematical Example - Civil Engineering

Saturday, 30 March 2019

How To Calculate Minimum Non Passing Sight Distance -Mathematical Example

Calculate Minimum Non Passing Sight Distance

Mathematical Example: Calculate the minimum non passing or say stopping sight distance on a highway at a descending gradient of 6% with following data: 
a) Design speed = 80 Km/h
b) Reaction time of driver = 2.5 Sec
c) Coefficient of friction between tire and road surface = 0.4

Mathematical Solution

Given, 
a) Design speed(V) = 80 Km/h
b) Reaction time of driver(t) = 2.5 Sec
c) Coefficient of friction between tire and road surface(f) = 0.4
d) Gradient (n) = 6%

We know, for descending gradient,
Stopping sight distance/non passing Sight distance 
= 0.278V.t + V²/254(f-0.01n)
= 0.278 ⨯ 80 ⨯ 2.5 + 80² / 254(0.4 - 0.01⨯6)
= 129.71 m
Answer: Non Passing sight distance or say stopping sight distance should be 129.71 m

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