Our engineers played a key role on the design-build team for the federally funded rehabilitation of this historic 1,700-foot-long bridge—a combination concrete girder and steel truss movable structure spanning the Thea Foss Waterway and the BNSF mainline. The project involved extensive structural repairs, including the replacement of the truss bottom chord, gusset plates, steel stringers, and bridge decks; installation of steel floor beams at expansion joints; and seismic retrofitting, which included strengthening truss members and tower columns, adding restrainers, jacketing columns, and replacing expansion bearings with isolation bearings. The team also modernized the bridge’s power distribution system.
Our Bridges and Structures group led the structural inspection and rehabilitation design for nine spans plus the fill portion of the Port Approach. Civil and structural design services included stormwater drainage and treatment design, engineering of the pedestrian access steel stairway, and design of protective fencing for the BNSF railway, as well as signage and striping for the entire bridge. Additionally, our team handled the seismic analysis, design, and load rating of the Port Approach. Due to the bridge’s location on the industrialized Thea Foss Waterway and the likelihood of contaminated soil and groundwater, the project required advanced stormwater runoff control. We designed an aboveground wet vault and storm filter system to capture runoff from the City Approach and portions of the Center Truss Span, as well as a bioswale to treat and infiltrate runoff from the Port Approach. To manage runoff from the movable lift span, we used a system of suspended troughs and catchment basins.
This project earned the 2013 Best Highway/Bridge Project Award from Engineering News-Record Northwest.