Friction course, which is known as porous asphalt, is often used as surface material in high speed roads and expressway. It is porous in nature which allows for speedy drainage of surface water. Road safety can be improved because it reduces the chance of hydroplaning/aquaplaning (i.e. there is a layer of water between the tires of the vehicle and the road surface. It may lead to the loss of traction and thus prevent the vehicle from responding to control inputs such as steering, braking or accelerating). It also decreases the splash and spray from vehicles in wet weather. It serves as a drainage channel for water to flow beneath the pavement surface.
Friction course has larger texture depth and this enhance improved skid resistance for vehicles traveling at high speed. It also has other benefits like the reduction of noise generated by vehicle tyres.
This question is taken from book named – A Self Learning Manual – Mastering Different Fields of Civil Engineering Works (VC-Q-A-Method) by Vincent T. H. CHU.
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