Friday, 31 August 2018

Length Of Transition Curve Design Method

Length Of Transition Curve

In this article i will show you how to design the length of transition curve,or say how to calculate or determine the length of transition curve.

The length of transition curve is designed to fulfill the three condition as mention below.The length of transition curve for design should be highest of the three values.

1.The rate of change of centrifugal acceleration to be developed gradually.From this consideration the length transition curve is given by the following equation:

Ls = 0.0215 V³/ CR
Where ,Ls = Length of transition curve in m, V = Speed of vehicle in Km/h , C = Rate of change of centrifugal acceleration, R = Radius of circular curve in m .
The minimum and maximum values of C are limited to 0.5 & 0.8 respectively.

2.The rate of introduction of designed super elevation to be at a reasonable rate.From this consideration the length of transition curve is given by the following :

Ls = e.N (W + We)/2
Where, e = The rate of designed super elevation ,W = Normal pavement width in m , We = Extra widening pavement at the circular curve in m. 1/N = Rate of change of super elevation (Minimum value of N is 150 to 60 ).

3.By Empirical formula: According to I.R.C standards, the length of horizontal transition curve should act ,than the value given by the following equations:

a)For plain and rolling terrain ,Ls = 2.7 V²/R
b)For mountainous and steep terrain, Ls = V²/R