From the Washington Policy Center:
The West Seattle Bridge was first opened to traffic in 1984, replacing a twin drawbridge (or bascule bridge) that had been struck in 1978 by the freighter Chavez. Its replacement – a segmental bridge supported by concrete girders – was supposed to last 75 years. It has, instead, lasted 35. This is unacceptable.
As I keep reading reports and articles, the questions that will not leave my mind are, “How could a bridge deteriorate so badly at only half of its intended lifespan?” and “Who didn’t do their job?”
Reports indicate that unless there are interim repairs to cracks and restrained bearings, and the 150-foot bridge is supported as soon as possible, there is a risk of failure, partial collapse, and potentially a full collapse of the entire main span. The Seattle Times reports what failure might look like here.