Question

what is the necessity of banking of roads

Answer 1

1. for increasing the speed limits of vehicles or object...generally in racing
2. for making turns...like in trains or railways

Answer 2

Also, the force of friction is not always reliable because it changes when roads are oily or wet due to rains etc. To eliminate this difficulty, the curvedroads are generally banked. Due to banking of the road, the necessary centripetal force is provided by the component of the normalreaction.