Camber is provided to the road to drain off the surface water from pavement. It is provided by riding middle portion of the road surface. Camber is provided to allow flow of water from the road surface to drainage system in lateral direction, where as minimum gradient is provided to allow gravity flow of water inside the drainage system in longitudinal direction.
It is measured in in 1 in n or n %. Main advantage of providing camber are quick drying of pavement which in turn increases safety and sub-grade protection protection by drainage.
Types of Camber or Cross-slope :
- Straight Line Camber
- Parabolic or Elliptic Camber
- Combination of Straight and Parabolic Camber
Straight Line Camber :
Made up of strong material mainly used for concrete or rigid pavement design.
Equation of camber,
Parabolic or Elliptic Camber :
For fast moving vehicle, most of time constructed by using bituminous material.
Equation of camber,
Where,
W = Width of pavement
N = Camber slope ( taken from IRC )
Combination of Straight and Parabolic Camber :
Camber Slope as per IRC:
|
Type
of Road |
High
Rainfall Area |
Low
Rainfall Area |
|
High type
Bituminous or Cement Concrete Surface |
2
% (1 in 50) |
1.7
% (1 in 60) |
|
Thin Bituminous
Surface |
2.5
% (1 in 40) |
2
% (1 in 50) |
|
Water Bound Macadam
or Gravel Surface |
3
% (1 in 33) |
2.5
% (1 in 40) |
|
Earthen Surface |
4
% ( 1 in 25) |
3
% (1 in 33) |
The camber of shoulder should be at least 0.5 % steeper than the cross slope of adjoining pavement, subjected to a minimum of 3.0 % and a maximum of 5.0 %.
Gradient provided for pavement is consider as a twice of camber, superior the road flatter the camber.
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