Method Of Providing Superelevation - Civil Engineering

Wednesday, 24 April 2019

Method Of Providing Superelevation

Method Of Providing Superelevation

Introduction of superelevation on a horizontal curve of a road is an important feature in road construction. Superelevation is provided in the following two methods.
  1. Elimination of the crown of the cambered section.
  2. Rotation of pavement to attain full superelevation.
Method Of Providing Superelevationv
Method Of Providing Superelevation

1. Elimination of The Crown of The Cambered Section

In this method, the outer half of the camber is gradually decreased. This may be done by two methods. 

In the first method, the outer half of the camber is rotated about the crown at the desired rate such that the surface falls on the same plane as the inner half.
Outer edge Rotated about the crown
Outer edge Rotated about the crown
In the second method, the crown is progressively shifted outwards. This method is not usually adopted.
Crown Shifted Outwards(Diagonal Crown Method)
Crown Shifted Outwards(Diagonal Crown Method)

2. Rotation of Pavement To Attain Full Superelevation

In this stage, superelevation is gradually provided over the full width of the carriageway so that the required superelevation is available at the beginning of the circular curve. 
The different method employed for attaining the superelevation is as follows:

A. Revolving Pavement About The Center Line

In this method the surface of the road is rotated about the center line of the carriageway, gradually lowering the inner edge and rising the upper edge. The level of the center line is kept constant. This method is widely used.
Rotation about the center line
Rotation about the center line

B. Revolving Pavement About The Inner Edge

In this method, the surface of the road is rotated about the inner edge, raising the center and outer edge.
Rotation about the inner edge
Rotation about the inner edge

C. Revolving Pavement About The Outer Edge

In this method, the surface of the road is rotated about the outer edge depressing the center and inner edge.
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