A roundabout is a type of circular intersection with a central island where traffic flows counter-clockwise. Vehicles entering the roundabout yield to vehicles already circulating, and vehicles operate at low speeds. According the U.S. Federal Highway Administration, roundabouts are often safer, more efficient, less costly and more aesthetically pleasing than conventional intersection designs.¹
Difference Between Roundabouts and Traffic Circles
Roundabouts are much smaller than older traffic circles (also known as rotaries) and require vehicles to negotiate a sharper turn to enter, forcing traffic to proceed at a lower speed – usually 15-25 miles per hour. Traffic circles typically allow higher speeds on the approach and within the traffic circle. With roundabouts, the potential for serious crashes is virtually eliminated due to lower speeds and because all vehicles travel in the same direction.²
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Each year, 7,000 people are killed and nearly 1 million people are injured in intersection-related crashes in the U.S. According to the AASHTO Highway Safety Manual, compared to conventional stop-controlled and signalized intersections, roundabouts reduce the types of crashes where people are seriously hurt or killed⁷.
Roundabouts are safer than traditional intersections, providing a 90 percent reduction in fatalities; a 76 percent reduction in injuries; and a 35 percent reduction in all crashes.³
In the video, Modern Roundabouts: A Safer Choice⁴, published by FHWA, roundabouts are noted as being more efficient, with lower costs and longer life span. The video states, “Traffic can move freely through roundabouts. This makes them more efficient than signalized or stop-controlled intersections.” Furthermore, the video notes that “Reduced vehicle idling means fewer emissions and less wasted fuel.” While initial construction costs can be higher than conventional intersections, roundabouts can often have lower operating and maintenance costs compared to signalized intersections. The Modern Roundabouts video reports that, “Roundabouts have longer service lives than traditional intersections resulting in better economic value over the long time, especially when you factor in the reduction of fatal and injury crashes.”⁵
Roundabouts are used around the world, and their use in the United States is growing as drivers experience, and appreciate, the benefits of improved traffic flow. Washington State alone has more than 150 roundabouts and the number is increasing.⁶
Highly visible reflective signs and pavement markings alert drivers they are approaching a roundabout, and instruct them on how to safely and correctly navigate through it. These guides play important roles in increasing drivers’ comfort level, confidence and perception of safety, particularly for drivers age 65 and older.⁷
¹,³,⁶ U.S. Department of Transportation Federal Highway Administration. Roundabouts and Mini Roundabouts, retrieved Nov 9, 2017.
²,⁷ Insurance Institute for Highway Safety Highway Loss Data Institute. Roundabouts, retrieved Nov 9, 2017.
⁴,⁵ U.S. Department of Transportation Federal Highway Administration. Roundabouts and Mini Roundabouts > Modern Roundabouts | A Safer Choice (PDF, 23.48 KB), retrieved Dec 6, 2017.