Multnomah County, Ore., selected Burnside Bridge Partners last month as the construction manager/general contractor for its $895-million Earthquake Ready Burnside Bridge project in Portland, Ore. The contractor is a joint venture of Stacy and Witbeck Inc. with Traylor Bros. Inc. and American Bridge Co.
The project is currently in the design phase led by prime consultant HDR. The project team is currently drilling for soil samples near the existing bridge to help inform the design, according to the county.
The project is planned to replace the existing Burnside Bridge over the Willamette River, which was completed in 1926. The bridge is a main route connecting the east and west sides of Portland—a designated emergency route in the event of a disaster and the only crossing in the area carrying a local road—but county officials say it was built with only light reinforcement on shallow timber piles embedded in soft soil, making it unlikely to withstand a magnitude 8 earthquake. The Cascadia Subduction Zone, which stretches from British Columbia to California, is estimated to be “overdue” for a major earthquake, based on historical data, officials say.
The new bridge is planned to be designed to modern seismic standards and to have a 100-year service life, according to HDR. It would include a movable bascule span in order to allow river traffic to pass with unlimited clearance.
The Burnside Bridge currently carries about 45,000 vehicles per day across the river plus thousands more pedestrians and cyclists. It crosses over nine interstate highway lanes, two railroad tracks, two light rail lines and parks, according to HDR. The planned 2,200-ft-long replacement bridge would include four lanes plus a dedicated bike and pedestrian path, and would be designed to accommodate future streetcar loads, the engineers say.
The Stacy and Witbeck-led team beat out a Skanska Flatiron Joint Venture for the job, county records show. The contractor did not immediately respond to inquiries. A county spokesperson says the selected joint venture “brings extensive experience with CM/GC delivery, construction of technically challenging and signature bridges and has demonstrated a dedication to diversity and equity in both subcontracting and workforce development in previous projects.”
County officials say use of the GC/CM model will allow for collaboration from the builders during design. They anticipate selecting a bridge type, form and materials by next summer, and completing the design with public input in 2026.
Construction and demolition of the existing bridge are scheduled to start mid-2026, and the new bridge is expected to open in spring 2031.