Seven bridges in Klamath Falls, Oregon to undergo seismic retrofitting

April 16, 2021

Bridges located on U.S. 97—a primary “lifeline route” in the event of a major earthquake

Seven bridges in the Klamath Falls area in Oregon will be the focus of a $32 million seismic retrofitting project that will begin this year and continue for the next four years.

The Oregon Department of Transportation says it is all part of a seismic resiliency plan spearheaded by the state of Oregon and funded by the federal government.

The bridges are located on U.S. 97, which is a primary north-south highway and “lifeline route” in the event of a major earthquake. Due to its inland location, U.S. 97 is expected to fare much better than the other primary north-south routes I-5 and U.S. 101—which will be badly damaged or completely destroyed in the wake of a Cascadia subduction event.

The state of Oregon has identified those seven bridges as the most vulnerable to a magnitude 8.0 or greater earthquake—the impact magnitude scientists expect when a Cascadia subduction event next occurs off the Oregon coast.

Geologists believe tectonic plates off the Oregon coast shift about every 300 years, causing a massive earthquake and tsunami. It has now been 321 years since Cascadia last struck, meaning it is now overdue. Additionally, the Klamath Falls has localized earthquakes, as evidenced by the Scotts Mill and Klamath Falls earthquakes in 1993.

Six of the project bridges will be retrofitted and another—U.S. 97 over Lakeport Blvd. and UP Railroad—will be completely replaced. U.S. 97 will be the first primary route to achieve its resiliency goal with the completion of the south U.S. 97 bridge bundle. A similar group was completed last year on the north end of U.S. 97 just south of Biggs Junction.

The work on the Klamath Falls bridges will be performed by a contractor who will be selected this summer by competitive bid, with bridge work starting after that and continuing for the next four years.

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SOURCE: Oregon DOT