Bellevue's first two roundabouts were full roundabouts, installed on West Lake Sammamish Parkway Southeast/180th Avenue Southeast, just north of Interstate 90. They were built by the state Department of Transportation, which maintains them. The most recent one was completed in 2013.
In 2019, the Bellevue Transportation Department added two “mini-roundabouts" to enhance safety and improve travel efficiency. A third one will be added in 2020. The mini-roundabouts will be at:
- 138th Avenue Southeast and Southeast 40th Street (completed, project mailer)
- 164th Avenue Southeast and Southeast Newport Way (completed, project mailer)
- 100th Avenue Northeast and Northeast 10th Street (scheduled for construction February-May 2020, project webpage)
A roundabout is a circular intersection with a center island that can be safer and more efficient than intersections with no island. In roundabouts, drivers and cyclists circulate counterclockwise around the island and those entering the roundabout yield to those already circulating. Vehicle speeds are kept low due to the curved design, and, unlike a four-way intersection with stop signs, stopping is not required unless one needs to yield before entering.
A mini-roundabout is a compact style of the roundabout, larger than a traffic circle but smaller than a full-size roundabout. The center island is designed to be driven over by the occasional large truck or bus.
- How Roundabouts Work video (2 minutes, Insurance Institute for Highway Safety)
- Driving Modern Roundabouts video (9 minutes, state Department of Transportation)
- Modern Roundabouts: A Safer Choice video (10 minutes, Federal Highway Admin.)
- Driving a semi-truck through a mini-roundabout video
- Driving a school bus through a mini-roundabout video (at 4:25 mark)
- How to drive a roundabout webpage (state Department of Transportation)
- 100th Avenue Northeast/Northeast 10th Street construction budget: Approximately $800,000 (partially funded by the Neighborhood Safety, Connectivity and Congestion Levy)
- 138th Avenue Southeast/Southeast 40th Street. The mini-roundabout is one of several construction elements in the Eastgate/Tyee Traffic Safety Improvement Project. The budget for the entire project is $925,000 (partially funded by the Levy)
- 164th Avenue Southeast/Southeast Newport Way construction budget: Approximately $600,000 (fully funded by the Levy)