Weeklong traffic snarl starts Friday on I-90

July 14, 2014

By Sam Kenyon

New: July 14, 1:58 p.m.

Drivers heading to Mercer Island or Seattle along I-90 should ready themselves for significant delays due to a large construction project that begins July 18. Westbound I-90 will be reduced to one lane for seven straight days as the Washington State Department of Transportation (WSDOT) replaces the expansion joints on the East Channel Bridge, which links Mercer Island to Bellevue.
WSDOT recommends all drivers utilize alternative strategies to reduce the inevitable traffic buildup.
“Traffic and delays are going to be hard to judge right now,” said Kris Olsen, a spokeswoman for the WSDOT. “A lot of it depends on what drivers do.”
Drivers are encouraged to use any and all resources to reduce their westbound I-90 commute such as carpooling, alternate routes, telecommuting, delaying discretionary trips, and only using westbound I-90 early in the morning or late at night.
“We’re thinking probably two and a half, three miles of backup probably if no one really changes their habits,” Olsen said.
The two expansion joints to be replaced are each 92 feet long and were installed in 1981. In 2001, WSDOT discovered that water was leaking into the joints due to a broken rubber seal. Water and contaminants flowed into the joints causing deterioration. Emergency repairs were made, but the rubber seal must be replaced. WSDOT estimates the project will cost $1.6 million.*
“They’ve reached the end of their useful life,” Olsen said. “We need to replace them now before we encounter a more serious problem, which would be a failure of the joint altogether.”
The expansion joints are necessary to allow the bridge to have some flexibility, to expand or contract due to weather conditions or traffic. Expansion joints also help protect bridges against seismic events.
The expansion joints over the pedestrian and bicycle path will also be replaced. The path will remain open during the day but pedestrians and cyclists can expect delays of up to five minutes from 10 p.m. to 5 a.m.
This project is too large to accomplish in a shorter time frame, since the huge joints are deeply embedded in the bridge. A typical weekend construction closure is about 55 hours, not long enough to replace the joints and pour the concrete.
“There are not enough hours in the course of a weekend,” Olsen said.
State Route 520 also has multiple weekend closures scheduled this summer, and the expansion joint repair project can’t overlap with any 520 closures.
“We can’t close I-90 and 520 at the same time,” Olsen said.
There are additional timing concerns as well, such as the Fourth of July and Seafair.
“Believe me, if we could break it up into overnights and weekends, we would,” Olsen said. “But it’s simply not possible considering everything we have to take into account.”
Mowat Construction has been awarded the contract for this project. All westbound I-90 lanes are expected to be open again at 5 a.m. July 25. WSDOT has offered a financial incentive to Mowat of $50,000 per day if they finish early, up to $100,000.

Sam can be reached at skenyon@snovalleystar.com or @samuel_kenyon.


*This version corrects the cost of the project.

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