Kerb indicates the boundary between the pavement and median or footpath or island or shoulder. It is desirable to provide kerbs on urban roads. Kerbs may be mainly divided into three groups based on their functions.

a) ‘Low kerb’ or’ mountable type kerb’ encourages traffic to remain in the through traffic lanes, yet allows the driver to enter the shoulder area at slow speed. The height of this type of kerb is about 100mm above the pavement edge with slop or batter to enable vehicles to climb the kerb at slow speed. This type of kerb is provided at medians and channelization schemes and is also useful for a longitudinal drainage system.

b) ‘Semi-barrier type kerb’ is provided on the periphery of a roadway where the pedestrian traffic is high. This type of kerb has a height of about 150mm above the pavement edge with a barrier of 1:1 on the top 75mm. this kerb prevents encroachment by the parking vehicles, but at cute emergency, it is possible to drive over this kerb with some difficulty.

c) Barrier type kerb is provided in built-up areas adjacent to footpaths with considerable pedestrian traffic. The height of kerbstone is about 200 mm above the pavement edge with a steep batter of 1.0 vertical 0.25 horizontal.

At times submerged kerb is provided on rural roads between pavement edge and shoulders. The submerged kerb provides lateral confinement and stability to the flexible pavements in general and to the granular base course of pavements in particular.