Skip Navigation LinksDOT > Projects & Programs > Road Design & Environment > Road Design > Roundabouts

ROUNDABOUTS

Safety

Roundabouts offer improved safety over other at-grade intersection forms because roundabouts have fewer conflict points, slower speeds, and easier decision making. When comparing a roundabout to a signal, studies show that roundabouts provide a 90 percent reduction in fatal crashes, 75 percent reduction in injury crashes, 30-40 percent reduction in pedestrian crashes, and 10 percent reduction in bicycle crashes. Roundabouts improve pedestrian safety offering two simple crossings of one-way traffic moving at much slower speeds.

 

Capacity

Roundabouts typically carry about 30 percent more vehicles than similarly sized signalized intersections during peak flow conditions. During off-peak conditions, roundabouts cause almost no delay, but traffic signals can cause delay to side street and left-turning traffic from the major street. Increased capacity at roundabouts is due to the continuously flowing nature of yielding only until a gap is available, versus waiting turns at a signal.


Videos

Because Pennsylvania is on track to install more roundabouts in the coming years, we've created this video to show you just how easy they are to navigate. After you watch the video, you'll know how to use both single and multi-lane roundabouts whether in a vehicle, on a bicycle or on foot. Keys to navigating a roundabout are to slow down and yield.

Swarthmore Borough in Delaware County constructed a roundabout on Chester Road (SR 0320). The video below gives an overview of the development and execution of the roundabout project to create a safer route for drivers and pedestrians. (Courtesy of McMahon Associates)