ROUNDABOUTS--THE STATE OF THE ART IN GERMANY

This article discusses the state of the art in roundabout design and operation in Germany and the issues related to both capacity and safety for motorists, pedestrians, and bicyclists. Compact, single-lane roundabouts have many advantages for intersections with traffic volumes of up to 25,000 vehicles per day. Within this range, roundabouts can be used to realize efficient and orderly traffic flows with very low delays and an exceptional level of traffic safety. Moreover, this innovative type of intersection usually results in lower construction (not counting potential additional right-of-way costs) and maintenance costs as a result of the reduced area and the absence of traffic signals. The possibility for aesthetically pleasing architectural or landscape treatments also argues for the use of compact roundabouts rather than conventional intersections. These positive experiences have resulted in an explosion in popularity for compact roundabouts throughout Europe. However, the success of roundabouts relies heavily on carefully following design guidelines and a thorough analysis of the likely operational characteristics to ensure that adequate capacity will be available to accommodate traffic demands.