Roundabouts: A Safer Choice

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Cars and a school bus entering a roundabout
Original source photo by Lee Rodegerdts.
Photo has been altered to illustrate roundabout and updated signage.

May 2008

FHWA-SA-08-006

U.S. Department of Transportation Federal Highway Administration

Safe Roads for a Safer Future - Investment in roadway safety saves lives

What is a roundabout?

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:

roundabout characteristics

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Why consider a roundabout?

Compared to other types of intersections, roundabouts have demonstrated safety and other benefits.

Roundabouts:

  • Improve safety
    • More than 90% reduction in fatalities*
    • 76% reduction in injuries**
    • 35% reduction in all crashes**
    • Slower speeds are generally safer for pedestrians

potential vehicle conflict points

  • Reduce congestion
    • Efficient during both peak hours and other times
    • Typically less delay
  • Reduce pollution and fuel use
    • Fewer stops and hard accelerations, less time idling
  • Save money
    • Often no signal equipment to install, power, and maintain
    • Smaller roundabouts may require less right-of-way than traditional intersections
    • Often less pavement needed
  • Complement other common community values
    • Quieter operation
    • Functional and aesthetically pleasing

Tips for safely walking or biking through a roundabout

"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

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Education is key.

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:

  1. Slow down.
  2. If there's more than one lane, use the left lane to turn left, the right lane to turn right, and all lanes to go through, unless directed otherwise by signs and pavement markings.
  3. Yield to pedestrians and bicyclists.
  4. Yield at the entry to circulating traffic.
  5. Stay in your lane within the roundabout and use your right-turn signal to indicate your intention to exit.
  6. Always assume trucks need all available space — don't pass them!
  7. Clear the roundabout to allow emergency vehicles to pass.

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.

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* "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.

Program Contact

What’s New

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South Carolina Case Study: Systematic Intersection Improvements

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Roundabouts: An Informational Guide, Second Edition (NCHRP Report 672)

Roundabouts Peer-to-Peer Assistance

How to drive a roundabout (WSDOT)

Modern Roundabouts: A Safer Choice

Highlights

FHWA's Intersection Resources Library CD-ROM

Roundabouts Technical Summary

Mini-Roundabouts Technical Summary

Access Management in the Vicinity of Intersections Technical Summary

Intersection Safety Case Studies

Intersection Safety Technologies

Presentation: Intersection Safety

Example Intersection Safety Implementation Plan

Intersection Safety Implementation Plan Workshop

Example Data Analysis Package and Straw Man Outline