A Review of the Literature on Design and Performance of Multi Lane Roundabouts in Canada: The Case for Turbo Roundabouts

Abstract

AbstractAs transportation system improvements, roundabouts have garnered support and interest from many countries due to traffic flow and safety improvements over traditional intersections. Despite growing application of roundabouts, knowledge and experience is lacking within Canada for design of multi lane roundabouts. Turbo roundabouts are an emerging multi-lane roundabout design successfully implemented in Europe over the past 20 years, however nowhere yet applied in Canada. Proven to reduce safety risk for all users (not just automobile), turbo roundabouts present a multi lane roundabout design option that warrants consideration for Canada; there is also more opportunity to implement this design due to increased capacity over a single lane roundabout. Many European research teams have demonstrated injury risk being significantly lower to auto and non auto road users by implementing this design. This lower risk is due to several design features, including spiral circulating lanes, physical lane dividers, and adequate separation for pedestrian crossings—among others. Existing Canadian design guidelines are mute on the topic of turbo roundabouts, and no manuals have been written pertaining to Canadian specific requirements. There are currently two roundabouts constructed in Canada that aspire to some aspects of turbo roundabout design features, despite hundreds constructed in Europe. This review identifies differences between available NA and EU multi-lane roundabout design literature, reasoning behind successes of the design, knowledge gaps, opportunities for improvement, and suggestions for development of consistent turbo-roundabout design guidelines in Canada.