Washington is home to approximately 7,500 bridges currently open to traffic, the Washington State Department of Transportation (WSDOT) recently reported.
While bridges open to traffic are safe to drive over, WSDOT has continued to receive less funding over several years than what is needed to maintain and preserve these structures, the department stated in a news release last week.
Lewis County has 420 bridges, 49 of which need repair or corrective action, two that are closed, 16 that have poor ratings from the United States Department of Transportation, and 20 that are structurally deficient.
WSDOT crews regularly inspect bridges and classify them as in good, fair or poor condition. Poor does not mean the bridge is failing, but that it needs more preservation from WSDOT.
A good rating means there are no problems or minor problems with structural elements. Fair means all primary structural elements are sound but might have some deficiencies such as minor section loss, deterioration, cracking, spalling or scour. Poor means these deficiencies have advanced and are affecting primary structural components. Poorly rated bridges may have truck weight limits but are not unsafe for travelers.
Bridges are inspected every two years, and bridges with concerns receive more inspections. Inspections can include dive teams for work under water, aerial inspections, under-bridge inspections and mechanical and electrical inspections for moving bridges.
While King County has a much higher population and more bridges, it has fewer poor-rated bridges — 22 — compared to Lewis County. WSDOT emphasizes that people should still feel safe crossing any open bridge and that ratings are more for the long-term outlook of the bridge.
WSDOT engineers say it is less costly to spend money on bridges earlier in the life of the bridge rather than wait for the bridge condition to worsen. Bridges tend to have a life expectancy of 75 years, but Washington has over 300 bridges that are 80 years or older. Age, however, is just one indicator of lifespan, and the overall condition of the bridge is more crucial.
Preventative maintenance, such as painting steel bridges, protects them against corrosion. However, when there is a lack of funding to paint bridges, rust and weakening of the structure can occur when otherwise the bridge would have been preserved.
WSDOT engineers say federal funding is helping, but there is a significant backlog in work on the state’s bridges.
Bridge collapses have made headlines nationwide as America’s infrastructure ages, including a bridge collapse over the Skagit River on Interstate 5 in 2013 in northwest Washington. Washington has an added factor to bridge health in seismic activity. WSDOT has a seismic retrofit program that works to minimize or avoid failures during an earthquake. More than 900 bridges in the state have gone through the program.
The state will also work on minimizing scour (the removal of soil by flowing water) around bridge piers and abutments. Streams and rivers can scour soil away, leaving a bridge foundation exposed and undermined. Scour is actually the leading cause of bridge failures nationwide.
There are more than 600,000 bridges in the United States, and Washington isn’t the only state grappling with bridge condition issues, WSDOT stated.
