Bridge Aging is the Biggest Threat Across the State

 US Highway 97 as it runs through Klamath Falls near Lake Ewauna. This stretch of US97 has several bridges that connect through the city of Klamath Falls. (file photo, Brian Gailey)

US Highway 97 as it runs through Klamath Falls near Lake Ewauna. This stretch of US97 has several bridges that connect through the city of Klamath Falls. (file photo, Brian Gailey)

SALEM – ODOT’s 2017 Bridge Condition Report (PDF) shows that, thanks to transportation investments over the past 16 years, the 2,742 bridges on the state highway system are in pretty good shape when judged by federal and state performance measures. Fewer than a quarter of ODOT’s bridges are rated as distressed, meaning they have structural or other deficiencies that limit their function or require attention (note: any bridges deemed unsafe for travel are closed immediately).

Still, state highway bridges are aging — nearly 50 percent of ODOT’s bridges were built more than half a century ago. With age comes a growing need to replace and repair bridges. HB 2017, the transportation funding package passed by the Oregon Legislature last year, will help maintain current conditions and prevent more bridges from falling into poor condition. ODOT’s economic analysis found that when bridges are weight-limited — meaning they can no longer carry heavy trucks due to structural problems — it becomes more expensive to get products from Oregon’s farms, forests and factories to market. This, in turn, makes Oregon’s trade-dependent economy less competitive.

Oregon’s aging bridge network has a number of vulnerabilities, such as many interstate bridges beginning to reach the end of their design life. We also have bridges built before modern seismic standards that will likely collapse or become unusable in an earthquake. Old timber bridges need regular repair, and coastal bridges need special treatment to withstand constant exposure to salt in the environment. ODOT’s budget prioritizes bridge preservation and maintenance to keep these bridges open to traffic, reducing impacts to businesses and communities.

ODOT has also developed a seismic strategy that will invest in replacing or retrofitting vulnerable bridges in phases. The first part of the first phase, which will secure U.S. 97 and Oregon 58 so that relief supplies can get into the state and across the Cascades into the Willamette Valley, has been funded. A triage route that will ensure southern Oregon is accessible was also funded by HB 2017, and ODOT expects to make continued progress on seismic resilience as a result of the investments made by HB 2017.

Here is an overview of the changes in the latest version of the Bridge Condition Report (PDF):

  • Bridge needs were updated using a model that is consistent with other analyses presented in the 2017 legislative session, such as that used in the Rough Roads Ahead 2 (PDF) report.
  • Bridge Program accomplishments are presented in two funding areas; there is also an update on seismic improvements due to funding in HB 2017.
  • Bridge Condition Summaries by District tables and the appendices are only available online this year. They can be accessed by clicking the “hot links” on the title of each appendix listed in the Table of Contents on page 3 of the report (you’ll need to wait a few seconds for the large files to load).