Questions have come up about the state of Seattle’s bridges in the wake of the I-5 Skagit River bridge collapse last week. Bridges are rated on a “sufficiency” scale of 0 to 100, with 100 meaning a sufficient bridge and 0 meaning a deficient bridge. As described on the Washington State Department of Transportation website, “The sufficiency rating doesn’t necessarily indicate a bridge’s ability to carry traffic loads. It helps determine which bridges may need repair or replacement, not potential for collapse.”
The I-5 Skagit River bridge was rated 57. As of last December, 37 of Seattle’s bridges had a sufficiency rating lower than 57, with several of those the subject of current or planned replacement or repair projects. A full list is available here.The Seattle Department of Transportation made a presentation on the status and condition of our city’s bridges in January. The slides from that presentation include some interesting charts and data points.