Washington bridge collapse

Yesterday a deck truss in Washington state near Mount Vernon collapsed while carrying four-lane Interstate traffic over the Skagit River.

The new mentions a truck present at the time of the collapse and may have struck an overhead member. Typically you would not think of sway bracing or other lateral members when you think of fracture critical bridges like a truss. This collapse has me thinking of a ways that might improve future designs, ratings and inspections of bridges (trusses).

Could the force of a collision cause a gusset plate to fail at a diagonal or vertical member of a truss?

Should gusset plate ratings incorporate checks for these addition collision loads?

Should we design our lateral members to shear at a desired force to not cause a collapse?

As always for inspections we need to check the vertical clearance at the portals and any lateral members over the roadway and verify that signs are in place in advance and at the bridge.

I look forward to hearing more about this collapse (that sounds bad) so that we can improve future designs, inspections and ratings.