Large-Scale Microscopic Traffic Behaviour and Safety Analysis of Québec Roundabout Design

Roundabouts are a staple of European road design with many international studies demonstrating important reductions in collision severity and, to a lesser extent, frequency, among other bene-fits. With the promise of better safety, roundabouts have recently proliferated across across North America as well. However, regional adoption has not been smooth and questions still remain regarding roundabout design and suitability in the context of North American driving culture. In-deed, driving behaviour is a vital component of a well functioning roundabout as all movements within are managed entirely by driving etiquette. To obtain a better understanding of how roundabout design affects driving behaviour at Québec roundabouts, a study of 37 instrumented weaving zones across 20 roundabouts throughout the province of Québec was conducted. The instrumentation captured continuous, high-resolution, microscopic movements and speeds fifteen times per second (trajectories) of over 80,000 individual vehicles over a combined 9,500 veh-km, one of the largest studies of its kind to date. This study looks at the effects of several geometric design and built-environment factors on the behaviour and safety indicators of speed and time-to-collision