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Friday, July 25, 2014
Kris Olsen, WSDOT communications, 206-440-4704
Hien Trinh, WSDOT project engineer, 206-768-5601
Congestion kept to a minimum during around-the-clock closures on the westbound East Channel Bridge
MERCER ISLAND – While contractor crews toiled to replace two massive expansion joints on the westbound Interstate 90 East Channel Bridge near Mercer Island, most drivers heeded the warnings and steered clear of the construction zone for the week.
Contractor crews working for the Washington State Department of Transportation closed all but one lane of westbound I-90 near Bellevue Way and three lanes across the East Channel Bridge from 9:30 p.m. Friday, July 18, to 4:25 a.m. Friday, July 25.
The lane closure threatened to cause large backups, but commuters took WSDOT’s advice to heart.
“We thank commuters for doing their part,” said Northwest Region Administrator Lorena Eng. “We asked them to do something different this past week by delaying trips, taking time off, telecommuting, carpooling, biking or leaving early. We even heard that people were boating across the lake. The bottom line is every time we need commuters’ help during big projects like this, they step up and respond.”
Generally, traffic engineers observed that the morning and evening commutes began and ended earlier than is typical. The longest average travel time was recorded on Monday morning, July 21, when it took drivers 34 minutes to travel from Issaquah to Seattle. At the peak of the morning commutes, there was a 40 to 60 percent diversion of vehicles off I-90. The diversion rate during the evenings averaged 35 to 46 percent.
Expansion joint work
During the past seven days, Mowat Construction crews worked around the clock replacing the expansion joints near each end of the westbound East Channel Bridge.
The previous joints were 33 years old and deteriorating. Despite previous repairs, the steel had continued to crack in spots and the protective rubber seals had broken. Removing the old expansion joints required crews to chip through concrete a foot deep and nearly three feet on either side of both expansion joints, cut through rebar and pull the expansion joints free.
The two new bridge expansion joints were installed in two halves, secured in place and welded together at the center points. New concrete was then poured around each 82-foot-long expansion joint.
Expansion joints are a critical component of how a bridge functions. They allow sections of a bridge to expand and a contract with temperature changes and different traffic volumes. Failing expansion joints are a safety hazard to drivers because they can pop up and damage vehicles. A failing expansion joint can also damage a bridge and, if the damage is severe enough, result in an unplanned, long-term closure while the expansion joint is repaired.
The new expansion joints have an expected life span of 30 years.
Nighttime I-90 trail expansion joint work next
The two bridge expansion joints under the I-90 bicycle/pedestrian trail will be replaced beginning Monday, July 28:
- Crews will close the two right lanes of westbound I-90 on the East Channel Bridge weeknights from 10 p.m. to 5 a.m. to access the trail and place construction equipment.
- One lane of the Interstate 405 ramp to westbound I-90 will also be closed nightly although the ramp will remain open.
During work hours trail users will be required to stop at the construction zone and then wait for a flagger to give them permission to proceed. No work will be performed from 5 a.m. to 10 p.m. At all times, users should use caution and be prepared to cross large steel plates on the trail at the expansion joint locations. This work is expected to last approximately two weeks.
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