Transportation Committee: March 2020 Connections Article

Ronald J. Young, Jr.
M.P.A., PA Department of Transportation
​Engineering District 5

Roundabouts are frequently installed to address intersections with safety issues but may also be installed to improve traffic flow as well as other reasons such as traffic calming, and to facilitate pedestrian mobility. 


The main characteristics of a modern roundabout include: generally circular shape; yield signs at the entrances; geometry that forces slower speeds; and counterclockwise circulation of traffic. Also, unlike traffic signals, roundabouts do not depend on electricity to function, so they are not susceptible to power outages. 

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PennDOT reviewed data for 11 roundabouts at intersections that were previously stop or signal controlled, and the review showed: 

· Fatalities were reduced by 100 percent (from two to zero); 
· Serious injuries were reduced by 100 percent (from seven to zero); 
· Minor injuries were reduced by 95 per- cent (from 19 to one);Crashes causing only property damage decreased by percent (from 49 to 48); and 
· Overall crashes dropped 47 percent (from 101 to 54). 


PennDOT’s District 5 opened round- abouts last year at US 222 and PA 662 in Berks County, and at the intersection of Broad Street, River Road, Foxtown Hill Road and the Interstate 80 Exit 310 ramps in Monroe County. 


Roundabouts are planned on the US 222 corridor at US 222, PA 863 and Schantz Road in Lehigh County, and several locations in Berks County. Learn more about these and other projects at www.projects.penndot.gov. 


Although roundabouts are safer and typically more efficient than signalized intersections, in many cases they may not be the best option due to topography or other reasons, such as property impacts, capacity issues and proximity to other intersections. Additional information on roundabouts can be found by searching at www.penndot.gov, key- word “roundabouts.

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