[scirocco22]

Originally Posted by GR8Scott

Sean, are you serious...2 out of 3. That's scary.

I really don’t think you should be that scared, GR8Scott. Personally, I’d be more scared about steel bridges failing like the one that recently collapsed in Minnesota. Both the Hood Canal bridge and the I-90 bridge sank during windstorms.

The Hood Canal bridge drawspan was open at the time to relieve pressure and closed to traffic because of the weather. The winds at the time were 80 MPH, gusting to almost 120 MPH. There’s always been a controversy about the bridge being built on salt water where it is subject to tide fluctuations but the bottom line for the February 1979 sinking was specifically the wind.

The I-90 bridge was under renovation and was closed to traffic to begin with. Some blame that disaster on bad decisions and errors pertaining to the reconstruction process that the bridge was undergoing at the time. The actual sinking in 1990 was due to water getting into the pontoons due to a storm which was happening. The bridge no longer has a drawspan to open during a wind storm but is engineered to now sustain high winds. The old I-90 bridge did have a drawspan and a buldge in the middle where motorist had to swerve twice around this obstacle and to add to that danger, it had reversible lanes where rush hour where traffic would be swerving around this buldge with only inches to spare between oncoming traffic. Oh, the memories!

The point is, that during high winds, conditions are monitored closely and traffic will be stopped. This is especially true on the SR-520 bridge where the wind conditions are monitored very closely and the bridge closed if warranted. It’s known that the SR-520 bridge is under-engineered and eventually will fail if not replaced soon. That is scary for its own reasons.

Here is a news clip for King5 of the I-90 bridge sinking on YouTube for those who have not seen it:


YouTube - I90 Bridge Sinks

We’ve posted this vid before but here is a simulation of a failure of the SR-520 bridge from the WDOT website on YouTube:


YouTube - SR 520 Floating Bridge - Simulated failure by wind storm