The main function of a roundabout is to secure the safe interchange of conflicting traffic flows with the minimum of delay to the road user. This is achieved by a combination of geometrical layout features related to the volume, type and speed of traffic using the junction, taking into account the needs of all road users (including pedestrians and pedal cyclists) and any site specific local conditions which may apply. The emphasis placed on any one factor varies and is dependent upon both physical and economic restraints. Vehicle entry deflection on the approach to the roundabout, and the angle at which the vehicle enters the roundabout, are the two characteristics which have the clearest influence safety because these features control vehicle speed. The purpose of this safety practice note is to highlight these and other features which have a direct bearing on the safe operation of roundabouts. (A)
Abstract