March 11, 2002
Engineers: Roundabout is safest alternative for SR-203 and N.E. 124th
by Lisa Allen
Valley View Editor
DUVALL-First, the good news. The state has enough money budgeted for right-of-way purchases and design engineering for the planned roundabout on SR-203 and N.E. 124th.
Now, the bad news. The project is currently unfunded for construction.
Washington State Department of Transportation (WSDOT) engineers say their hope is to have the roundabout completed in the fall of 2003. But, said DOT Project Engineer David Edwards at a Duvall Chamber of Commerce meeting last week, "It is still a maybe. If the gas tax goes through, the project should be funded, but we still don't know."
WSDOT engineers have been planning the roundabout for the increasingly dangerous and congested intersection for several years. Many residents, though, have questioned whether a roundabout is the right design for that particular intersection. Some say they would prefer a traffic light, claiming the roundabout would take too long to build, be too expensive and is not appropriate for the 55 mph road.
But state engineers favor the roundabout for safety reasons.
"There are many benefits and advantages of roundabouts," Edwards pointed out. "(Because of the safety issue) more and more roundabouts are being built in the U.S. They work well to address traffic accidents and congestion."
Edwards explained that the large traffic circles were created in Great Britain and are commonly used there and in Europe. There are 300 in the U.S. in operation and 300 more are planned, he said.
Twenty-one roundabouts are in use or planned in Washington state. The closest one to Duvall was recently constructed on SR-522 at164th St./Tester Road in Monroe. The state is also planning one for the SR-202 and SR-203 junction in Fall City.
Edwards said statistics have proven that roundabouts reduce the number and severity of accidents, increase capacity and reduce delay, provide traffic calming, reduce operating and maintenance costs, decrease overall costs of construction and minimize impacts to the environment.
Roundabouts, Edwards explained, operate on a one-way traffic circulation that is regulated by a "yield at entry rule." The driver enters when there is a gap in traffic. Speeds run about 25 mph and splitting islands direct traffic to the right.
"The safety improvement is substantial," he said. "They have resulted in considerable reduction in injury accidents. There are only eight vehicle conflict points, as opposed to 32 in a signalized intersection."
Edwards said accident reduction can be traced to the facts that there are fewer contact points, lower speeds and less decision-making needed by the driver.
Roundabouts also require less maintenance as opposed to signals and there are environmental benefits because motorists don't have to wait at intersections, which results in less exhaust and pollution, he added.
Five significant benefits, he said, are improved safety, increased capacity, economy (less pavement widening), environmental improvements and appearance, which is enhanced if the island is landscaped.
Studies have indicated that delays per car would be 5.4 seconds using the roundabout, and 21.7 seconds with a traffic light.
Several residents at the meeting remained skeptical, however, and wondered about the larger size of trucks used in this country (as opposed to Europe and England), and how they would navigate their way around the island.
Edwards responded that the roundabout has been designed to accommodate the largest trucks, including trucks and trailers from Cadman Gravel.
He said the state looked at other options for the heavily used highway (considered in state language as a rural, minor arterial), including a signalized intersection with turn lanes or a divided highway, but concluded the accident rate and traffic delays would remain high with those alternatives as growth in the area continues.
"With those options, in a few years, we would be back to square one," he said. "The roundabout will increase capacity. One-way circulating traffic is the only movement. Right turns are used for entry and exit. It is a continuous flow."
He cited figures that show roundabouts reduce all accidents by 39 percent, injury accidents by 76 percent and fatal accidents by 90 percent.
The state DOT will hold a public meeting on the proposed roundabout on Wednesday, March 27, 5-8 p.m. at Cedarcrest High School in Duvall.