Design types of cycle facilities at roundabouts and their effects on traffic safety: some empirical evidence

Abstract

Roundabouts in general have a favourable effect on traffic safety, at least for crashes causing injuries. Especially the number of severe crashes (fatalities and crashes involving serious injuries) appears to decrease after converting intersections into roundabouts. Less is known about the safety effects of roundabouts for particular types of road users, such as bicyclists. A before-and-after study with the use of a comparison group on a sample of 90 roundabouts in Flanders-Belgium was conducted in order to assess the effects on crashes with bicyclists. This study revealed a significant increase in the number of severe injury crashes with bicyclists after the construction of a roundabout. Roundabouts with cycle lanes perform worse, regarding injury crashes with bicyclists, compared to three other design types (mixed traffic, separate cycle paths and grade-separated cycle paths). Roundabouts that are replacing signal-controlled intersections seem to have had a worse evolution compared to roundabouts on other types of intersections.