Definition
The convexity provided to of the surface the carriageway is called as Camber or Cross slope.
Or
Definition
The rise given to the centre of carriageway above its edges on a straight portion of a road is called as Camber or Cross slope

Purpose

Purposes of providing camber to carriageway are:

i. To drain off rainwater from the road surface as quickly as possible to prevent the entry of surface water into the subgrade soil or into the bituminous pavement layers.
ii. To regulate the vehicles to the proper lanes.
iii. To improve the architectural appearance on the roadway.

Recommended values of camber for different types of Road Surfaces