Commuters, prepare for huge Interstate 90 delays

July 15, 2014

By Sam Kenyon

One westbound lane will close for seven days

Drivers of westbound Interstate 90 should ready themselves for significant delays due to a $1.6 million construction project that begins July 18.

Westbound I-90 will be reduced to one lane near Bellevue Way for seven days as the Washington State Department of Transportation replaces the expansion joints on the East Channel bridge, which connects Mercer Island to Bellevue over a small channel of Lake Washington.

Prepare for traffic backups June 18-25 as workers repair two 92-foot-long expansion joints that  are deteriorating on Interstate 90 near Mercer Island.

Prepare for traffic backups June 18-25 as workers repair two 92-foot-long expansion joints that are deteriorating on Interstate 90 near Mercer Island.

Three lanes of westbound I-90 will be open at the Bellevue Way interchange as the ramps from Bellevue Way and Interstate 405 join I-90.

WSDOT recommends all drivers change their driving habits to reduce the inevitable traffic buildup.

“Traffic and delays are going to be hard to judge right now,” Kris Olsen, a spokeswoman for the WSDOT, said in a phone interview last week. “A lot of it depends on what drivers do.”

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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.

During the closure, WSDOT engineers expect the best times to travel will be before 6 a.m., between 11 a.m. and 2 p.m., and after 7 p.m. More than half of the 85,000 drivers who use westbound I-90 each day must use an alternate travel mode to keep travel time from Issaquah to Seattle at less than one hour.

“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, each 92 feet long, were installed in 1981. In 2001, WSDOT discovered that water was leaking into the joints due to a broken rubber seal. Water and contaminates flowed into the joints causing deterioration. Failing expansion joints are a safety hazard to drivers and can cause a bridge to bend, crack or even collapse. Emergency repairs were made, but the rubber seal cannot be fixed. It must be replaced.

“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.

The project is too large to accomplish in a shorter time frame, like a weekend closure. 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.

“It’s just the nature of this particular work, unfortunately,” 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.

Mowat Construction has been awarded the contract for the 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.



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