Portland City Council Authorizes $28M for Seismic Retrofits of Historic Willamette River Bridges

PORTLAND, OR — The Portland City Council and the Multnomah County Board of Commissioners authorized a joint $28-million seismic resiliency funding package on Sunday afternoon to upgrade foundational structural supports on historic Willamette River crossings.

Engineering Scope and Seismic Damper Architecture

The capital investment finances Phase 1 of the Willamette River Seismic Lifeline Program, focusing on the Hawthorne Bridge (constructed in 1910) and the Morrison Bridge (constructed in 1958). Civil engineering contractors will install high-capacity fluid viscous dampers, reinforce underwater concrete piers with steel jackets, and replace aging mechanical expansion joints.

The engineering retrofits are designed to ensure that critical river crossings remain structurally passable for emergency medical and first responder vehicles following a major Cascadia Subduction Zone seismic event.

"Our bridges are essential lifelines that connect East and West Portland," Multnomah County Chair Jessica Vega Pederson said. "Investing in seismic retrofits today ensures our city can respond effectively and maintain emergency connectivity after a major earthquake."

Transit and River Navigation Protection

The Hawthorne Bridge carries over 30,000 daily motor vehicles, 12 TriMet bus routes, and 8,000 daily cyclists and pedestrians. County engineers confirmed that the seismic reinforcement work will occur primarily from river barges, minimizing daytime traffic lane restrictions on bridge decks.

Maritime commercial river operators confirmed that navigation channels beneath the vertical lift spans will remain fully operational during construction.

Construction Timeline

Marine construction bids will be awarded in late autumn 2026, with on-water pier retrofits commencing in spring 2027.