Determine the length of transition curve having 6 degree curvature. The speed of the curve is 60 kmph and cant is 12 cm. Assume the track to be metre gauge.

Determine the length of transition curve having 6 degree curvature. The speed of the curve is 60 kmph and cant is 12 cm. Assume the track to be metre gauge.

Sol. Given,
Degree of curve, D= 6°
Speed, V= 60 kmph
Cant, e= 12 cm

We know that,
Radius of curve, R = 1718 / D= 286.33 m

Now the length of curve (transition curve) can be obtained by using following relations –

(i) Length of transition curve according to formula based on arbitrary gradient of 1 in 720,

L = 7.20 x e = 7.20 x 12 = 86.4 m

(ii) Length of transition curve according to formula based on rate of change of cant deficiency,

L= 0.073 x D X Vmax
L= 0.073 x 5.1 x 60 = 22.34 m

(:: D = 5.1 cm upto 100 kmph speed)

(iii) Length of transition curve according to the formula based on rate of change of superelevation,

L= 0.073 x e x Vmax
L= 0.073 x 12 x 60 = 52.56 m

The length of transition curve is adopted as maximum of the above three values. Hence,

Length of transition curve = 86.4 m

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