Here we go again: I-5 bridge over Skagit River (Washington) collapses; cars in water

[madokie]

83. We're not talking about the member that is designed to take a vehicle hitting it

we're talking about the overhead brace that is never hit. This was not a car that hit is it was an over-sized load that generally are heavy hitting the upper part of the truss/bridge, a part that is more susceptible to causing what happened here. Did you listen to the guy who was a witness to what happened. Its not rocket science.
Listen to the interveiw with the gentleman who was right in front of this truck whose over-sized load that hit it. He explains that they were going 60 mph and when the load hit it it caused the truck to lift way up and lean way over then it dropped back down and how that section of the bridge then shuttered and then starting to collapse.
You are trying to make a mountain out of a mole hill. Once a member of a truss type bridge is compromised as this top member would have been then all bets are off in this bridge continue to stand.
You show me a bridge that has had this type of damage and its still standing. There simply isn't one and if there is its a miracle that it does.
Listen to the interview with a Mr. Ogden who was there when and witnessed what happened. its at the link provided in the op.