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https://www.nationalacademies.org/trb/events

Crash Modification Factors for 2 by 1, Peanut-Shaped and Oval-Shaped Roundabouts

Roundabouts are well-regarded for their positive impact on road safety. Their unique design and traffic flow characteristics contribute to smoother traffic patterns, decreased congestion, and reduction in crashes and severity of collisions compared to traditional intersections controlled by traffic signals or stop signs. Studies conducted in various countries, including the United States, have consistently shown that roundabouts lead to a substantial decrease in both the frequency and severity of crashes. While there may be a learning curve for drivers unfamiliar with roundabouts, the long-term safety benefits are undeniable. As a result, many communities across the US have embraced roundabouts as a proactive measure to improve road safety and reduce traffic-related injuries and fatalities. North Carolina Department of Transportation (NCDOT) has been involved in various intersection and interchange rebuild projects in recent decades. 2x1, peanut, and oval-shaped roundabouts could prove to be a good alternative in many situations. The current literature on the safety impact of 2x1, peanut, and oval-shaped roundabouts is limited. The purpose of this project is to help NCDOT make optimum decisions on roundabout conversions. To realize this purpose, the primary objective of this research is to develop crash modification factors (CMFs) for 2x1, peanut, and oval roundabouts. Having reliable CMFs would allow NCDOT to compare the potential safety impacts of 2x1, peanut, and oval roundabouts to other intersections. By using a reliable CMF, NCDOT can make decisions that are expected to provide the biggest bang for the buck and reduce crashes and injuries.