Roundabouts have been a popular system for intersections outside downtown zones in urban areas in Switzerland for more than 10 years. One form of small roundabout becoming more common in Switzerland is the system with short two-lane approaches and a single-lane extrawide circulatory roadway. Research shows that small roundabouts with two-lane entries with a single-lane extrawide circulatory roadway have capacities 20% to 30% higher than those with single-lane entries, although the space requirements are almost identical. The fact that roundabouts with two-lane entries and a single-lane extrawide circulatory roadway have shown good performance with respect to capacity, traffic flow, and driver behavior, as well as a high level of safety, has led to an increasing use of this type of roundabout in Switzerland.
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