# Railway Engineering Questions and Answers – Superelevation

This set of Railway Engineering Multiple Choice Questions & Answers (MCQs) focuses on “Superelevation”.

1. What is the definition of Superelevation?
a) Difference in height between outer and inner rail
b) Height difference from outer rail to centre of track
c) Height difference from inner rail to centre of track
d) Slope at which rail is laid

Explanation: Superelevation or cant is the difference in height between outer and inner rail on a curve. The outer rail is gradually lifted above the inner rail to provide this.

2. Which of the following is also known as another name of inner rail?
a) Slope rail
b) Fixed rail
d) Cant rail

Explanation: Inner rail is also known as Gradient rail. It is taken as reference rail while determining superelevation and is normally maintained at its original level.

3. In case of equilibrium speed what is the angle between resultant of weight and radial acceleration and plane of rails?
a) They are perpendicular
b) Inclined at 45°
c) Tangential
d) Between 45° and 90°

Explanation: Equilibrium speed is when the effect of centrifugal force is completely balanced by the cant provided. The resultant of weight and radial acceleration is perpendicular to plane of rails.

4. What should be done if maximum permissible speed is less than maximum sectional speed?
a) More cant should be given
b) Another Curve should be inserted
c) Permanent speed restrictions should be implemented
d) No alterations should be made

Explanation: Maximum permissible speed is the highest speed at which a train is permitted to travel on a curve. If it is less than maximum sectional speed, permanent speed restrictions should be imposed.

5. Which of the following occurs when train travels at a speed greater than equilibrium speed on a curve?
a) Cant deficiency
b) Cant excess

Explanation: Cant deficiency is the difference between theoretical cant required and the actual cant provided. When train travels at a speed lesser than equilibrium speed on a curve cant excess occurs.
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6. Which of the following is the correct formula for equilibrium superelevation in millimetres?
a) e = GV2/254R
b) e = GV2/381R
c) e = GV2/127R
d) e = GV2/96R

Explanation: Equilibrium superelevation, e = F x G/W
= W/g x V2/R x G/W
= GV2/gR
e = GV2/127R in millimetres.

7.The superelevation that is to be provided on a curve depends only on the maximum speed of the fastest train.
a) True
b) False

Explanation: The superelevation to be provided also depends on the average speed of the goods traffic moving on the section. This is done to make sure that slow trains move safely without any chances of derailment due to excess cant.

8. A per the prescribed value, what should be the maximum value of cant excess on Broad gauge?
a) 65mm
b) 75mm
c) 92mm
d) 100mm

Explanation: Higher cant excess on a section that carries predominantly goods traffic can lead to wear of the inner rail. Thus it is limited to 75mm on BG and should not be more than 65mm on MG.

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