Explaining differences in safety performance of roundabouts

Abstract

The conversion of an intersection into a roundabout has been proven to reduce in general the number of accidents with injuries or fatalities. However, evaluation studies frequently showed considerable individual differences in safety performance of roundabouts or particular groups of roundabouts. The main purpose in the present study was to explain the variance in safety performance of roundabouts through the use of risk models on accident data, traffic data, and geometric data of a sample of 90 roundabouts in Flanders-Belgium. The resuts hsow that the variation in accident counts is relatively small and mainly driven by the traffic exposure. Bicyclists and moped riders are more frequently than expected involved in accidents at roundabouts. Roundabout with cycle lanes close to the roadway are clearly performing worse than roundabouts with separate cycle paths. Confirmation is found for the existence of a "safety in numbers"-effect for bicyclists, moped riders and -more uncertain- for pedestrians at roundabouts.