# Which one of the following is the correct standard for provision of curves on railway track?

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Which one of the following is the correct standard for provision of curves on railway track?
1. Cant excess on B.G. shall not be allowed to exceed 105 mm
2. Minimum radius of vertical curves for group A, Brand Gauge track is 4,000 m
3. The minimum value of super-elevation according to Railway Board is $\frac{1}{{10}}$th of gauge
4. The speed potential of curve is given by formula $e= \frac{{{V^2}}}{{127\;R}}$ where, e is super elevation in mm.

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Correct Answer - Option 2 : Minimum radius of vertical curves for group A, Brand Gauge track is 4,000 m

Statement I: False

The maximum allowable cant excess is

For BG – 75 mm

For MG- 50 mm

For NG- 40 mm

Statement II: True

The minimum value of radius of vertical curves for Brand Gauge track for various groups is as follow:

For Group A – 4000 m

For Group B-  3000 m

For Group C, D and E- 2500 m

Statement III: False

The maximum value of super-elevation of different gauges is given below:

 Track Speed < 120 kmph Speed > 120 kmph BG 16.5 cm 18.5 cm MG 10 cm - NG 7.6 cm -

As one can see from the above table, the maximum value of super-elevation lies in between 1/10th to 1/12th of the gauges.

Statement IV: False

The equilibrium super-elevation for given speed or speed of the curve for given super-elevation is calculated from the formula:

$e = \frac{{G{V^2}}}{{127\;R}}$

Where E is super-elevation in mm; G is the gauge of track width of railhead in mm; R is the radius of the curve in meters.