Blue Bridge #538 - (#RC1549)
View a larger map. West pier looking east during 2006 flooding
April 17, 2013 Update: A single lane closure will be in effect April 22 - May 3, 8:30am-4pm. Snohomish County PUD will relocate power poles in preparation
for this bridge project.
Blue Bridge #538 crosses the South Fork Stillaguamish River on the Mountain Loop Highway 12.06 miles outside of Granite Falls. It is a two-lane, 160-foot long structure built in 1954 consisting of three spans: a 160-foot long steel through-truss main span and two 24-foot cast-in-place concrete approach spans. The spans are supported on two concrete piers and two concrete abutments, all founded on concrete spread footings.
A major flood event in 2006 on the South Fork of the Stillaguamish River eroded approximately 150 feet of the left bank upstream from the east pier, causing the bank to recede approximately 25 feet. The flood also washed away the soil fill between the west pier and west abutment at the bridge.
Since 2006, both ends of the bridge have required extensive hydraulic, structural and environmental planning to address the repairs. An east side bank stabilization project was completed during 2010. The west side retrofit is scheduled for construction in 2013.
Snohomish County is proposing a retrofit project that will include installing new deep-drilled piers at the west end of the bridge and protecting the west side roadway with an engineered revetment to provide long term stability of the embankment. View the newsletter below for more details and photos.
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- Steve Miller, Project Manager, (425) 388-3488, ext. 4225
- Tina Hokanson, Communications Specialist, (425) 388-3789
You can check the Weekly Road Construction Update to see what else is happening on Snohomish County roads.