# What is the limit of reduction in cant for a speed of 120 kmph on broad gauge track?

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What is the limit of reduction in cant for a speed of 120 kmph on broad gauge track?
1. 7.6 cm
2. 8.6 cm
3. 8.0 cm
4. 10.0 cm

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Correct Answer - Option 4 : 10.0 cm

Explanation:

The cant at which loads on two rails are equal is called equilibrium cant.

Cant deficiency is the difference between equilibrium cant necessary for maximum permissible speed on a curve and the actual cant provided.

Given,

Speed = 120 kmph > 100 kmph

∴ Cant Deficiency for BG Track for V > 100 kmph is 100 mm = 10 cm

Maximum cant deficiency:-

 Gauge For speed   up to 100 kmph For speed   > 100 kmph B. G 75 mm 100 mm M. G 50 mm – N. G 40 mm –

Equilibrium cant $= \frac{{{\rm{G}}{{\rm{V}}^2}}}{{127{\rm{R}}}}$

V - Design speed (kmph)

R - Radius of curvature (m)

For B.G track G = 1.676

$\begin{array}{l} {\rm{Cant}} = \frac{{1.676{\rm{\;}}{{\rm{V}}^2}}}{{127{\rm{\;R}}}}{\rm{m}}\\ {\rm{e}} = \frac{{1.315{\rm{\;}}{{\rm{V}}^2}}}{{\rm{R}}}{\rm{cm}} \end{array}$