California Department of Transportation District 1
 

All About Roundabouts

Cordata Parkway Roundabout, Bellingham, WA
The multi-lane Cordata Parkway Roundabout in Bellingham, Washington. Photo courtesy of Reid Middleton, Incorporated

What are roundabouts, and what are their benefits?

A roundabout is an intersection where traffic travels around a central island in a counterclockwise direction. Vehicles entering or exiting the roundabout must yield to vehicles, bicyclists, and pedestrians.

Roundabouts can have many advantages over traffic signals when constructed in the right location, including:

  • They provide traffic calming, resulting in reduced speeds.
  • They require less maintenance, have lower yearly operational costs, and have a longer service life.
  • They reduce greenhouse gas emissions by reducing vehicle idling time.
  • The median islands provide refuge for pedestrians, allowing them to cross one direction of traffic at a time.
  • They provide additional opportunities for landscaping in the community.

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Tips for motorists navigating roundabouts
Taken from the Department of Motor Vehicles' California Driver Handbook

When you approach a roundabout:

  • Slow down as you approach the intersection.
  • Yield to pedestrians and bicyclists crossing the roadway.
  • Watch for signs and pavement markings that guide you or prohibit certain movements.
  • Enter the roundabout when there is a big enough gap in traffic.
  • Drive in a counterclockwise direction. Do not stop or pass other vehicles.
  • Use your turn signals when you change lanes or exit the roundabout.
  • If you miss your exit, continue around until you return to your exit.

roundabout lane control sign example

For roundabouts with multiple lanes, choose your entry or exit lane based on your destination. For example, to

  • Turn right at the intersection, choose the right-hand lane and exit in the right-hand lane. (Blue car)
  • Go straight through the intersection, choose either lane, and exit in the lane you entered. (Red car)
  • Turn left, choose the left lane, and exit. (Yellow car)

Multi-lane roundabout image