This paper was presented at the session titled `Risk management in the roads sector - geometric design'. Modern roundabouts have been in widespread use in Europe and in Australia for many years; however, their introduction into North America came much later. Interest in roundabouts has grown rapidly in the United States during the past few years, but has only recently caught the attention of Canadian organisations. Many municipal engineers and even traffic experts are, however, reluctant to implement roundabouts. Roundabouts of the past, or rather traffic circles, had their share of critics, rendering their rebirth and the refocusing of interest in this area difficult. It is important to differentiate the modern roundabout from the traffic circle of the past. The objective of this paper is to distinguish the differences between the two and to eliminate misperceptions associated with roundabouts in terms of capacity and operating characteristics. To begin, an historical review of modern roundabout development is presented. Traffic experts often compare roundabouts to signalized intersections or to 4-way stop intersections. These three intersection types will be compared on several levels, focusing on safety, capacity, and how they fit into the urban planner's context. The results of well-accepted methods of capacity analysis will be presented. A few roundabouts designed for municipalities within the Montreal region will serve as references during this presentation, and their conceptual design plans will be given to those present. In conclusion, it illustrates the signing used in this first roundabout in Eastern Canada and will review its history. (A)
Abstract