March 25, 2002
Roundabout will reduce severe accidents and keep traffic moving
The Washington State Department of Transportation (WSDOT) is planning to construct a two-lane modern roundabout on State Route 203 at NE 124th Street near Duvall. Given the nature of the intersection, and increasing traffic volumes, a roundabout is an ideal fit to keep severe accidents to a minimum while keeping the traffic flowing smoothly. There are several compelling reasons to install roundabouts at intersections, but the most important one is safety. Roundabouts have been shown to reduce injury crashes as much as 76 percent.
Currently, there are over 300 roundabouts in use throughout the United States and 21 existing or planned roundabouts in the state of Washington. Many studies show that roundabouts are significantly safer than traffic signals. The number and severity of accidents is reduced by the lower speeds that vehicles travel through the intersection.
Roundabouts are generally cheaper to construct than intersections with traffic signals because less space is required and there are fewer potential environmental impacts. A signalized intersection on SR 203 at NE 124th would require grading, realignment and left and right turn pockets long enough to keep the through lane moving and prevent traffic backups. The additional asphalt creates more environmental requirements and increases costs. Yearly signal maintenance costs are also avoided with a roundabout.
The roundabout on State Route 203 at NE 124th Street has been designed to accommodate the long truck and trailer combinations that use the intersection. We are also planning more public education to ensure that the drivers who will be using the roundabout fully understand how to use them.
Last summer, a roundabout was constructed in Monroe at the State Route 522 off-ramp to 164th St./Tester Road. Accidents have been reduced and long traffic backups on the off-ramp and Tester Road from the local high school dissipate much faster than before the roundabout was constructed.
I hope that this letter answers many of the questions that have been raised concerning the modern roundabout project on State Route 203 at NE 124th Street. If you have any other questions about the SR 203 Roundabout project, please feel free to contact me at (206) 440-4312 or firstname.lastname@example.org.
David Edwards, Design Engineer, WSDOT Northwest Region office in Shoreline