The bridge inspection by MnDOT would have noted any significant casson erosion. The safety factors on these bridges would allow you to park trucks stacked 3 high on top of each other in bumper to bumper before you’d be at the limits. It’s the simultaneous and complete failure of both trusses that bother me. This thing should have twisted if 1 side went. It didn’t.
That’s what I would think as well.. Thanks re: the load limit.
also, They did have a heavy water flow scenario not so long ago. Just a thought.
I am sure they will be looking at every possibility as to any contributing factors for the collapse.
When its brand new, yes. But over time, exposed to de-icing and nature, elements deteriorate, concrete has a half life of 20 years, less when exposed to the spray from traffic.
They were working on this bridge, had the two outside lanes open to traffic, and equipment parked in the inside lanes. It looks like the bridge seperated at an expansion joint.
My original comment last night about the bridge looking like it had dropped straight down was close.
Why did those supports fail? My guess right now would be construction operations.
Same thing almost happened to a bridge I was working on in 1998.
Interesting how both ends seem to have given way at once.
One lesson that has to be learned from past experiences is that erosion is not a linear-rate process. Unfortunately, many engineers have not learned that simple geologic fact, from channel erosion to beach loss.
That being said, I don't think there's much evidence that caisson/pier failure was involved in this case, and I certainly don't know the qualifications of the MnDOT inspectors.