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.