A brief introduction describes the development of modern, small roundabouts in Switzerland. Recent case studies show the effects on safety, Public Transportation and environmental impact. The results indicate that small roundabouts have a lower casualty rate than any other type of intersection. At accident black spots, small roundabouts generally decrease the accident rate. Small roundabouts do help improve pedestrian and cyclist safety. However careful design is required to provide the best results. Cyclists should be integrated in the roundabout lanes and there should be no separate cycle routes. Motorists should be forced to decrease speed by the layout of the roundabout and traffic islands should be provided at every approach. As regards environmental impact, studies showed that the introduction of the roundabout decreased fuel consumption by up to 16%, which indicates that exhaust fumes would also be decreased. The reduced amounts of acceleration and deceleration should also produce less traffic noise. Two different methods (VSS/Emch and Berger and Bovy) for the estimation of capacity are also presented and are compared to international formulas. Finally a concise overview on the recently published Swiss Roundabout Guide is given.
Samenvatting