OP-ED: The bridge is history; It's time for an Immersed Tube Tunnel
By Bob Ortblad
Civil Engineer (ret), MBA, CPA
All the king's horses and all the king's men
Couldn't put Humpty together again.
The West Seattle-High Level Bridge is a shallow arch bridge supported by two box girders. These box girders have a thin concrete shell. Restoring the strength of these cracked girders can be compared to super-gluing a cracked egg. Cracks have crossed the box girder floors and climbed up the walls at 45 degrees to within inches of their roofs.
These cracks are forming a 200-foot long, 4,000-ton upside-down keystone.
Even if the bridge is somehow repaired, it will be forever crippled. Nevertheless, the city plans to spend a stopgap $33 million to shore it up and prevent a complete collapse.