A roundabout is a type of circular intersection where entering traffic yields to traffic within the center circle. The modern roundabout is designed with splitter islands on the approaches, and appropriate roadway curvature to reduce vehicle speeds. The term ‘modern roundabout’ is used to differentiate today’s roundabout from other circular intersections. For example, roundabouts are typically smaller than the large, high-speed rotaries still in use in some parts of the country. Additionally, roundabouts are typically larger than neighborhood traffic circles used to calm traffic.
The following benefits of modern roundabouts were assembled from the Federal Highway Administration website:
- Up to a 90% reduction in fatalities
- 76% reduction in injury crashes
- 30-40% reduction in pedestrian crashes
- 75% fewer conflict points than four way intersections
Slower vehicle speeds (under 30 mph)
- Drivers have more time to judge and react to other cars and pedestrians
- Advantageous to older and novice drivers
- Reduces the severity crashes
- Keeps pedestrians safer
Efficient traffic flow
- 30-50% increase in traffic capacity over four way intersections
Reduction in pollution and fuel use
- Improved traffic flow for intersections
- Reduced need for storage lanes
- No signal equipment to install and repair
- Savings estimated at an average of $5,000 per year in electricity and maintenance costs
- Service life of a roundabout is 25 years (vs. the 10-year service life of signal equipment)
- Traffic calming
- Aesthetic landscaping
For video describing how roundabouts work, see the Insurance Institute for Highway Safety.
See the Washington Department of Transportation for information on how to drive through a roundabout.
Five Part Video Series on Roundabouts:
Part 1: Roundabouts: What they are and what they are not.
Part 2: How do I drive a roundabout?
Part 3: Pedestrians and cyclists.
Part 4: Safety benefits.
Part 5: What does this mean for me?