U.S. Department of Transportation
Federal Highway Administration
1200 New Jersey Avenue, SE
Washington, DC 20590
Original source photo by Lee Rodegerdts.
Photo has been altered to illustrate roundabout and updated signage.
A roundabout is a type of circular intersection with yield control of entering traffic, islands on the approaches, and appropriate roadway curvature to reduce vehicle speeds.
Modern roundabouts are different from rotaries and other traffic circles. For example, roundabouts are typically smaller than the large, high-speed rotaries still in use in some parts of the country. In addition, roundabouts are typically larger than neighborhood traffic circles used to calm traffic.
A roundabout has these characteristics:
Compared to other types of intersections, roundabouts have demonstrated safety and other benefits.
"Personally, I love them, and I'll tell you why. You only have to stop one lane of traffic, then go to the middle and wait. The cars can't go much faster than 20 mph through the roundabout so the crossing aspect is great."—Denise Haltom, School Crossing Guard, Suamico, Wisconsin, Green Bay Press-Gazette, February 6, 2001
"We have had a lot of people not very happy about the idea of roundabouts, but after they are constructed, those fears mostly go away."—Brian Walsh, Washington State Department of Transportation, Seattle Times, June 5, 2002
"We all know people speed up to get through a yellow light. But at the roundabout, all the vehicles have to slow down … we have almost 50 roundabouts now, we have a lot [fewer] personal injuries. We have fewer fatalities."—James Brainard, Mayor, City of Carmel, Indiana, www.nbc17.com, November 8, 2007
Education is vital to the acceptance and success of a roundabout. Navigating a roundabout is easy. But because people can be apprehensive about new things, it's important to educate the public about roundabout use.
There are just a few simple guidelines to remember when driving through a roundabout:
Visit safety.fhwa.dot.gov to learn more about roundabouts.
Source: Roundabouts: An Informational Guide. Federal Highway Administration, Washington, D.C., latest version, except as noted.
Note: Design standards for roundabouts continue to evolve, and not all features of existing roundabouts meet current recommended practice. Please refer to FHWA's web site for recommendations on current design practice.
* "Safety Effect of Roundabout Conversions in the United States: Empirical Bayes Observational Before-After Study." Transportation Research Record 1751, Transportation Research Board (TRB), National Academy of Sciences (NAS), Washington, D.C., 2001.
** NCHRP Report 572: Roundabouts in the United States. National Cooperative Highway Research Program, TRB, NAS, Washington, D.C., 2007.