All About Roundabouts
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.
- Roundabouts in the United States (PDF 2.2M)
- Glorietas en los Estados Unidos (PDF 2.0M)
- Caltrans Roundabout Inventory
Watch a video:
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.
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)