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SR 302 Roundabout Pre-Design Study – Why Roundabouts

Why Roundabouts

Studies have shown that roundabouts are safer than traditional stop sign or signal-controlled intersections. Roundabouts reduced injury crashes by 75 percent at intersections where stop signs or signals were previously used for traffic control, according to a study by the Insurance Institute for Highway Safety (IIHS).

How do roundabouts help reduce the likelihood and severity of crashes?

Low travel speeds – Drivers must slow down and yield to traffic before entering a roundabout. Vehicle speed within the roundabout is typically between 15 and 20 miles per hour. The few crashes that occur in roundabouts are typically minor and cause few injuries since they occur at such low speeds.

No light to beat – Roundabouts are designed to promote a continuous, circular flow of traffic. Drivers need only yield to traffic before entering a roundabout; if there is no traffic in the roundabout, drivers are not required to stop. Because traffic is constantly flowing through the intersection, drivers do not have the incentive to speed up to try and “beat the light,” like they might at a traditional intersection. This is also beneficial when the power goes out. There is no confusion over an all-way stop.

One-way travel – Roads entering a roundabout are gently curved to direct drivers into the intersection and help them travel counterclockwise around the roundabout. The curved roads and one-way travel around the roundabout eliminate the possibility for T-bone and head-on crashes.

Reduce Delay and improve traffic flow – Contrary to many peoples’ perceptions, roundabouts move traffic through an intersection more quickly, and with less congestion on approaching roads. Roundabouts promote a continuous flow of traffic. Unlike intersections with traffic signals, drivers do not have to wait for a green light at a roundabout to get through the intersection. Traffic is not required to stop – only yield – so the intersection can handle more traffic in the same amount of time.

Less expensive to maintain– Traffic signals are high maintenance. They need electricity, software, and electrical components to operate. Roundabouts are more affordable to maintain.

How do I drive a roundabout? For information about driving a single lane roundabout, also known as a compact roundabout, check out this video created by the Virginia Department of Transportation (VDOT) or read our brochure. The VDOT mini roundabout is comparable to WSDOT’s single-lane roundabout. (https://www.youtube.com/watch?app=desktop&v=fUFmuf_HRDg)

Want to experience driving a similar high-speed roundabout?

Visit and drive a similar high-speed roundabout located in Spokane, Washington on SR 902 at the South Craig Road intersection. View the roundabout in the photo below, or on Google Maps.

A street view photo example of a high-speed single-lane roundabout located in Spokane, Washington on SR 902 at the South Craig Road intersection.
Example of a high-speed single-lane roundabout located in Spokane, Washington on SR 902 at the South Craig Road intersection.

If I ride a bike, what are my options at a roundabout?

Bicyclists can choose, depending upon their comfort level, whether to:

  • Ride with traffic through the roundabout
  • Walk their bicycles through a pedestrian crosswalk. For additional information, visit WSDOT’s walking and biking through roundabouts website.

For more information about roundabouts, visit WSDOT’s roundabout webpage.

To learn more about these topics and other benefits of roundabouts, visit our roundabout webpage. (https://wsdot.wa.gov/travel/traffic-safety-methods/roundabouts)