Transition Curve

In this article we discussed the following :-

what is transition curve 

what are the purpose of transition curve

what are the requirements of transition curve

types of transition curve

Transition curve

Transition curve

It is a  non- circular curve introduced between a straight and circular curve is known as transition curve. The curvature of such curve varies from zero at its beginning to a definite value at a point of meeting with with circular curve.

Purpose of transition curve

to increase curvature gradually 

it is an medium for gradual introduction of super elevation 

to Provide Extra widening gradually 

to Increase comfort to passenger on curve 

to Reduce overturning 

to Allow higher speed 

to reduce wear on gear, tyre 

Requirement of transition curve

Tangential to straight

Meet circular curve tangentially

At origin curvature should zero.

Curvature should be same at the junction of circular curve.

Rate of increase of curvature should be equal to rate increase of super elevation.

Length of transition curve should be equal to full super elevation attained.

Types of transition curve

Cubic parabola used For railway 

Spiral or Clothoid  it is Ideal transition curve 

Lemniscates used for road