Davis Slough Bridge, SR 532
- Oct 10, 2012
The original Davis Slough highway and bridge was built in the 1950s and spans the mount of the Stillaguamish River and a railroad spur line. It is the only bridge to Camano Island.
The replacement 400-ft long 3-span bridge meets current earthquake standards, requires less maintenance, and provides wide shoulders to accommodate disabled vehicles and emergency responders. The new bridge was built with precast concrete girders and a cast-in-place concrete deck containing epoxy-coated reinforcing steel. The 190-ft main span represents one of the longest precast, prestressed girder spans in the Pacific Northwest.
The new bridge is designed to withstand a 1,000-year seismic event without collapsing, despite deep onsite alluvial fills that have a high potential for liquefaction during a significant earthquake. Impacts to the surrounding estuarine wetlands and streams were also minimized during construction.