The spirits said:
The engineering investigation will reveal the bridge collapsed due primarily to design or construction flaws dating from the time of the bridge’s construction in 1968.
The I-35W bridge was entirely supported by two main trusses, composed of many small pieces of steel bolted or welded together like a child’s Erector Set. Though it is possible to design a steel truss bridge with redundancy, the I-35W bridge was supported only by those main trusses.
“A truss arch bridge is like a chain — if you try to take out one link, you lose the whole system,” said Abolhassan Astaneh-Asl, a UC Berkeley professor who is an expert in such bridges. “They are very vulnerable to instability.”
Astaneh compared a steel truss system to a house of cards, which will quickly collapse if one card is pulled out.
In a comment to the previous post, commentator Chel asked:
Our governor (as you know spirits, I’m a Minneapolis resident) just vetoed a 5 cent gas tax increase which would have been the 1st one in 20 years.
The spirits replied:
What happened to all the previous tax money? Insurance and maintenance cost should be part of life cycle operating cost of any system. In the private second, not accounting for such future cost constitutes fraud. . The maintenance of existing infrastructure should always take precedence over new flashy construction. What spending priorities changed?
Dorgan said there was enough money in the agency’s budget to pay for construction work on the underside of the bridge
Read the entire article for context. I am too exhausted to consult the spirits right now, but how much do you want to bet we will find out that, just as in the Challenger explosion, some group of MnDOT inspectors and engineers warned higher-ups about the strong possibility of catastrophic failure — but that the higher-ups chose to pursue the course of action which just happened to be the cheapest short-term solution?
I may hang up my shingle and go into the psychic business.