New State Study Shows Roundabouts’ Continued Safety

HARRISBURG PA – Fatalities, injuries, and crashes decreased overall after intersections at 33 locations were replaced with 36 roundabouts, according to results of a review of Pennsylvania Department of Transportation data for roundabouts on state routes with intersections previously controlled by stop signs or signals, the department reported Monday (Sept. 19, 2022).

The review included the roundabout opened during 2009 at Route 29 and Route 73 in Zieglerville, Lower Frederick Township (at top); as well as one in Berks County and three in Chester County. They and 31 other sites were selected because each had at least three years of crash data available before and after the roundabouts were built.

Data from 2002 through 2021 shows suspected serious injuries were reduced by 76 percent, suspected minor injuries were reduced by 22 percent, the number of possible and unknown severity injuries was reduced by 70 percent, and the total number of crashes decreased by 9 percent. One fatality has occurred in one of the roundabouts, compared to three fatalities before the installation of roundabouts.

The department published results of similar studies during 2021, 2020, and 2018.

Roundabouts that met the state’s selection requirements represent roughly half of all built in the state. Thirty-eight others are elsewhere on Pennsylvania highways; 16 more under construction; and 15 more are in final design stages, according to the department. They are often installed to solve intersection safety issues, but may also be built to improve traffic flow, traffic calming, and pedestrian mobility.

Roundabouts are safer and typically more efficient than traditional signalized intersections. However, the state said, they may not always be the best option due to topography or other reasons, such as property impacts, capacity issues, and proximity to other intersections.

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