Burnside Bridge Seismic Resiliency Study

CLIENT Multnomah County

Location Portland, OR

Oregon is located on the Cascadia Subduction Zone, a fault that causes regularly occurring megathrust earthquakes.

Portland’s Burnside Bridge was designated as a lifeline route across the Willamette River in the event of an emergency, supporting traffic for emergency services, evacuation, and recovery immediately after a major disaster. Constructed in 1926, the Burnside Bridge was not designed with seismic resiliency in mind and the existing bridge is not expected to withstand a major seismic event.

Shannon & Wilson participated in a study to determine how the Burnside Bridge will respond to an earthquake, and to identify replacement or rehabilitation alternatives. The Burnside Bridge is a relatively complex structure sited in a dense urban area, and understanding how it will react to an earthquake is further complicated by the variable geology supporting the bridge. Our study used FLAC 2D numerical modeling to model the complex interactions of the subsurface soils and the structure itself.

Based on subsurface explorations, laboratory testing, and FLAC analysis, Shannon & Wilson provided Multnomah County with options for both retrofitting the Burnside Bridge to withstand a significant seismic event, and for constructing a new bridge that would be both compatible with existing infrastructure and economically sustainable long term.

transportation Highways / Roads
GIS / Database Management Geotechnical Engineering Geologic Hazards
Portland Seattle


2018 Oregon ACEC Engineering Excellence Awards - Honor Award


Elizabeth Barnett
Senior Geologist

Jeremy Butkovich
Vice President

Adrian Holmes

Aimee Holmes
Senior Engineer & Geologist

Jerry Jacksha
Senior Associate

Eric Paslack

Bill Perkins
Vice President, Earthquake Engineering Services

Park Piao
Vice President

Ali Shahbazian

James Walters

Seattle Website Design