The Pennsylvania Department of Transportation says data collected from nearly a dozen roundabouts across the state reveal their design has resulted in a significant decrease in crashes, injuries and fatalities.

PennDOT recently reviewed data for 11 roundabouts on state routes that were previously stop sign or signal-controlled intersections.

The roundabouts were selected based on having at least three years of data available before and after they were installed.

For the years 2000 through 2017, crash reports submitted by police show fatalities and serious injuries were reduced by 100 percent while the total number of accidents dropped by 47 percent.

PennDOT Project Development Engineer Jeff Bucher said the safety of roundabouts can be attributed to vehicles moving through the curved design at slower speeds and at an angle as they yield to circulating traffic.

“Crashes are typically minor in nature and are sideswipes instead of the severe T-bone and head-on collisions that occur at other types of intersections,” Bucher said.

Bucher noted that there are factors that would disqualify an intersection for conversion into a roundabout.

“If it’s on a hillside or if there is a sensitive cultural resource or property in one of the quadrants, that could result in us going with a different option than a roundabout,” he added.

Bucher also said any roadway that sees more traffic than about 20,000 vehicles a day would not be an ideal location for this design.

Two of the 11 roundabouts reviewed were in southwestern Pennsylvania. One is at the intersection of Ewing and Resurrection roads in Moon Township. The second location is where Route 68, Adams Street, intersects Brighton Avenue in Rochester Borough.

In addition to the 11 roundabouts studied, PennDOT says 32 others have been installed on state routes and 26 are in design. In Allegheny County, PennDOT is proposing construction of a roundabout at the intersection of McLaughlin Run and McMillan Road in Upper Saint Clair Township.