PUBLIC OPINION, TRAFFIC PERFORMANCE, THE ENVIRONMENT, AND SAFETY AFTER THE CONSTRUCTION OF DOUBLE-LANE ROUNDABOUTS

摘要

This study evaluated the impact of double-lane roundabout conversions on public attitudes, trafficperformance, the environment, and safety at two intersections near Bellingham, Washington, andevaluated whether older drivers avoided the roundabouts by taking an alternative route. Driver supportfor the roundabouts increased from 34% before construction to 70% one year after. One year afterconstruction, more than 40% of drivers did not believe the signs and pavement markings adequatelyconveyed information about appropriate speeds, right-of-way rules, or navigating the roundabouts in thepresence of large trucks. After accounting for other roadway changes, substantial declines were attributedto the roundabout conversions in the delays and queue lengths on minor roads, the proportion of queuedvehicles, and fuel consumption and vehicle emissions. Analyses of crash rates per entering vehiclesfound that the roundabout conversions were associated with reduced rates of injury and fatal crashescombined and increased rates of property damage-only crashes. Only the increase in the propertydamage-only crash rate at one roundabout was significant. The odds that drivers 70 and older traveled thestudy corridor versus an alternative route after the roundabout conversions was 0.32 times the oddsbefore. These findings generally are consistent with prior research finding substantial traffic,environmental, and injury-reduction benefits of single-lane roundabouts. However, it seemed the greatercomplexity of double-lane roundabouts may present challenges as some confusion persisted one year afterconstruction, there was evidence that some older drivers may have taken an alternative route to avoidthem, and property damage-only crash rates increased.