Length Of A Valley Curve Problem and Their Solution

17th April 2019 0 By Malay Sautya

Length Of A Valley Curve Problem and Their Solution

Calculate the length of a valley curve when ascending, descending gradient and design speed is given:

Mathematical Problem

A valley curve is formed by a descending gradient of 1/20 meets with an ascending gradient of 1/30. Design speed 85 km/h allowable rate of change of centrifugal acceleration is 0.61 m/s³. Find the length of valley curve for comfort.

Mathematical Solution

Given, 
c = 0.61 m/s³
Design speed(v) = 85km/h = 23.61m/s 

Now,
N = [(-1/20) – (1/30)] = 0.083

Length of Valley Curve

L = 2[Nv3 / c]1/2

L = 2 [( 0.083⨯23.613) / 0.61]1/2 

L = 2 ⨯ 42.31 = 84.6m

Read Also:

Find The Stopping Sight Distance To Avoid Head on Collision

Find Headlight And Intermediate Sight Distance