SYNTHESIS OF ROUNDABOUT IMPLEMENTATION PRACTICES

摘要

Roundabouts are a relatively new type of intersection control in Canada, and as such there is growing interest in how they compare relative to established types of control using stop signs and traffic signals. Roundabouts have a clear set of advantages and disadvantages compared to these traditional intersections, which are set out in Section 2 of this paper. Intersections play an critical role in the operation of a road network. Therefore it is important to make sound defensible decisions about type of intersection control, both when implementing a new intersection and when modifying an existing intersection (or road section) due to motor vehicle capacity or user safety issues. When stop and traffic signal control were the only alternatives this process was straightforward and accomplished using traffic signal warrants based on side street delay and historic safety performance. Now that roundabouts are a possible alternative the process is potentially much more complicated. A number of road agencies in Canada and the United States have developed practices to aid in making a decision about type of control. A selected range of these practices is described in Section 3 of this paper as well as practices in Australia, which is a country with similar density and road network characteristics as Canada and the US but a much longer history of roundabout implementation. Section 4 of this paper synthesizes the various roundabout implementation practices descried in Section 3 as being either basic intersection-level, "enhanced" intersection-level, or network-level.