An epidemiological approach to explain crash risk and crash severity for different types of road users at roundabouts

Abstract

Although roundabouts exist almost as long as cars do, they only became common in continental Europe during the 80’s and the 90’s of the twentieth century. In North America they even emerged only recently. Knowledge and insights on traffic operations and safety on roundabouts have evolved considerably. Roundabouts have some intrinsic properties that are believed to improve traffic safety when they are constructed: they reduce speeds considerably and they decrease the number of possible conflict points between road users. Apart from their effects on traffic safety, roundabouts are considered to be adequate intersection types for accommodating high traffic flows, particularly in case of high quantities of left turning traffic. Nevertheless some uncertainties exist on the safety effects of roundabouts. Particularly for bicyclists and pedestrians the effects are less clear. Also the effects of some design elements are not yet fully understood. These elements justified the execution of a PHD project on safety issues at roundabouts. The main objective of this dissertation was therefore to extend existing scientific knowledge on safety performance of roundabouts, based on state-of-the-art empirical research. ...