February 11, 2002
Engineers mitigating traffic impacts of bridge closure
by Lisa Allen
Valley View Editor
DUVALL—Traffic will be monitored and flaggers will be stationed at critical intersections to help mitigate the impacts of this summer's Woodinville-Duvall Bridge closure, King County engineers told residents at an informational meeting last week at Cedarcrest High School.
The bridge will be closed for repair from June 24 to Sept. 30. The project will cost $2.5 million.
Traffic Systems Engineer Norton Posey, who helped steer motorists through the six-month Novelty Bridge closure in 2000, said King County did an extensive study on the impacts of either a three-month total closure or five months of a one-lane closure.
"We discovered the impacts on traffic would be similar," he said. "So we decided to close the bridge to get it all done in three months."
He said flagging will occur at SR-203 and N.E. 124th and SR-203 and 203rd St. during peak hours. The new light at W. Snoqualmie Valley Road and N.E. 124th will be monitored by traffic cams and adjusted by technicians as needed, and signals will be retimed at all the major intersections, he added.
"We decided flagging is as good or better than signals," he said. "Officers can respond quickly to changing traffic patterns and it will be much cheaper. At a cost of $125,000 to $200,000 for a signal, it's just not viable."
Jim Markus, supervising bridge engineer, said King County engineers want to repair the bridge on their schedule and not wait until the1,182-foot-long structure is in such poor condition it has to be closed.
He said the bridge is not in danger of falling down, but that engineers don't know how long it will be before the structure could be considered too dangerous to use.
"We have serious concerns," he said. "There are a lot of deficiencies. It is an important bridge and we want to restore the community's ability to use the bridge. We need to do it now on our own terms."
Engineer Ken Wilson said there is significant cracking on the main and approach spans which carry 17,000 cars daily.
"The bridge was built in 1951 for vehicles with a 27-ton capacity, but the current truck load is 36 tons, which is 33 percent more weight," he said. "This has increased the damage, reduced the useful bridge life and has meant more maintenance. There are four deficiencies: load capacity, deck condition, rail deficiency and seismic vulnerability."
The Virginia Street transition to the bridge will also be improved, which will aid trucks making turns, he said.
"Completion of the project will assure community mobility, maintain the useful life of the bridge, improve public safety and allow for the removal of the posted load limit," he concluded.