Test: Superelevation - Civil Engineering (CE) MCQ

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.

Superelevation:
It is the transverse slope to counteract the centrifugal force and to reduce the tendency of the vehicle to overturn or skid.
It is the rise of the outer edge of the pavement w.r.t inner edge on a horizontal curve thus providing a transverse slope throughout the length of the horizontal curve
It is also known as cant or banking.
Rate of Super elevation = e = tan⁡θ = E/B
Where,
E = Total superelevated height of the outer edge
B = Width of the pavement
General equation,

where,
f = Coefficient of lateral friction = 0.15
R = Radius of horizontal curve
It can be seen that the superelevation is directly proportional to the velocity of the vehicle
Mistake point:
The rate of superelevation is inversely proportional to the width of the pavement, but the superelevation is not. Superelevation is directly proportional to the velocity of the vehicle.

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.

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.

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