Slayden-Sundt Opens $227M Sellwood Bridge in Portland

PORTLAND, Ore. – Multnomah County and Slayden-Sundt, a joint venture of Slayden Constructors and Sundt Construction, Inc., recently celebrated the opening of  Multnomah County’s new $227-million Sellwood Bridge in Portland, Oregon.

Serving as the construction manager/general contractor for the 2,000-foot-long bridge, Slayden-Sundt replaced the original, deteriorating structure with a wider, pedestrian-friendly bridge that can accommodate the area’s growing traffic volume. Originally built in 1925, the bridge is the community’s only crossing over the Willamette River for 12 miles, making it the state’s busiest two-lane bridge as well as an iconic piece of architecture.

Designed by T.Y. Lin International as an open-spandrel steel deck arch structure, the new bridge complements the immediate surroundings and features two vehicle lanes in each direction on the west end, which narrow to one lane in each direction on the east end. The bridge also has two six-foot-wide bike lanes and two 12-foot-wide sidewalks.

Though the bridge has opened to the public, crews will continue removing the old bridge and completing additional work on the east and west sides of the Willamette River.

Slayden-Sundt broke ground on the project just over four years ago in December of 2011, and employed a number of innovative approaches along the way to help reduce disruption to the community and provide greater protection for the environment. Most notably, the team utilized a bold approach to construct the new bridge in the footprint of the existing structure without shutting down traffic flow. Rather than rebuilding the bridge in sections and shifting traffic back and forth between structures and newly completed segments, the team created a “shoofly” bridge.

The approach involved lifting the old bridge deck and truss with hydraulic jacks and moving it to one side, then placing it on a set of temporary piers and connecting it to temporary approach spans so that traffic could continue to use it while the new bridge was constructed. The 1,100-foot-long steel bridge truss was moved in a single 12-hour operation and became one of the longest bridge sections ever to be moved.