Question

Total angle of deflection of a transition curve is
1. Spiral angle
2. Spiral angle / 2
3. Spiral angle / 3
4. Spiral angle / 4

Answer 1

Correct Answer - Option 3 : Spiral angle / 3

Explanation:

• The deflection angle, ϕ, at a set-up on the T. S . from the tangent to any point on the spiral is the angle whose tangent is x/y.
• It is unnecessary to compute x and y since the deflection angle is very nearly equal to one-third of the spiral angle. 
• The correction is small for small values of the spiral angle and less than half a minute for the values less than 21°.

Spiral angle:

The angle between the initial tangent and the common tangent at the junction of the transition curve and the circular curve is called the spiral angle.