Roundabout Safety Analysis in the Context of Time Series: Case Study in the State of Pennsylvania

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Roundabout Safety Analysis in the Context of Time Series: Case Study in the State of Pennsylvania

Coffey, S. / Park, S. / Zoccoli, N.

Safety is always an essential consideration when planning an infrastructure system. Hence, it would undoubtedly be beneficial to design roadways in a manner that prevents crashes and reduces the severity of the crashes that still occur within the intersection. This study aims to identify the safety benefits of converting a standard intersection into a roundabout. Crash data from fourteen selected Pennsylvania intersections was used to compare the injury severity level and crash type statistics of crashes from before and after the roundabout’s implementation. The aforementioned crash data comparisons demonstrate that the conversion of a standard intersection into a roundabout leads to significant reductions in the severity of injuries during crashes. The results from the comparison also indicated a large decline in the frequency of angle and rear-end crashes, with a corresponding increase in hit-fixed-object crashes. Furthermore, economic and comprehensive crash costs of each injury severity level were acquired, and a before-after analysis determined that the fourteen intersections had saved a combined $35.6 million in comprehensive costs that include economic costs to society and the impact on driver’s quality of life. Based on the Pennsylvania roundabouts within this study, the results indicate the safety benefits of converting standard intersections into roundabouts. Future work would include expanding the analysis dataset to include multiple states to create a more statistically significant and confident conclusion.