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Equilibrium Superelevation:

Equilibrium superelevation is that superelevation at which pressure at the inner and outer tyre will be equal. if the coefficient of friction is neglected i.e. f =0 then,

e=$$\frac{V^{2}}{127R}$$    , V in km/h

This means that if a road surface is super elevated by tan-1$$\frac{V^{2}}{127R}$$  then the friction force will not be called upon to act and thus the pressure on both the wheel will be equal.

eequilibrium =$$\frac{V^{2}}{127R}$$

If the superelevation provided is less than eequilibrium lateral fiction will come into play and will go on increase as the superelevation gets reduced.

Note⇒ Due to equilibrium superelevation:

• No overturning, No Toppling, No Skidding, No Sliding.
• Pressure at the inner and outer tyre will be equal.

Superelevation As Per IRC

1.Maximum Superelevation

 Type of Road Maximum Superelevation (emax) Urban Road 4% or 0.04 Plain & Rolling Terrain 7% or 0.07 Mountainous & Steep Terrain 10% or 0.10

2.The minimum superelevation

It is provided on a road must not be less than the camber of the road for the adequate drainage of water from the surface.

For Detailed Analysis of Highway Engineering Step By Step.

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