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I-90 Eastbound Ramps and Canyon Road Intersection Improvements – How to drive a roundabout

Roundabouts are designed to make intersections or interchanges safer and more efficient for drivers, pedestrians and cyclists. There are two types of roundabouts: Single-lane roundabouts and multi-lane roundabouts.

The roundabout we will be building at the intersection of the eastbound ramps of I-90 and Canyon Road is a single-lane roundabout.

Single-lane roundabout
An example of single-lane roundabout.

Driving single-lane roundabouts

As you approach a roundabout, you will see a yellow “roundabout ahead” sign with an advisory speed limit for the roundabout.

Roundabout ahead road sign

Slow down as you approach the roundabout, and watch for pedestrians in the crosswalk.

Continue toward the roundabout and look to your left as you near the yield sign and dashed yield line at the entrance to the roundabout. Yield to traffic already in the roundabout.

Once you see a gap in traffic, enter the circle and proceed counterclockwise to your exit. If there is no traffic in the roundabout, you may enter without yielding.

Look for pedestrians and use your right turn signal before you exit.

The benefits

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). Studies by the IIHS and Federal Highway Administration have shown that roundabouts typically achieve:

  • A 37 percent reduction in overall collisions
  • A 75 percent reduction in injury collisions
  • A 90 percent reduction in fatality collisions
  • A 40 percent reduction in pedestrian collisions

There are several reasons why roundabouts help reduce the likelihood and severity of collisions:

  • Low travel speeds – Drivers must slow down and yield to traffic before entering a roundabout. Speeds in the roundabout are typically between 15 and 20 miles per hour. The few collisions 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 don’t have the incentive to speed up to try and “beat the light,” like they might at a traditional intersection.
  • 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 collisions.