Minneapolis Bridge Collapse

I'm betting that many local governments and corporations decided it was cheaper to take the chance on a failure rather than spend the money to detect and fix what might be a problem; and the dice has been rolled a few too many times.

Butrflynet wrote:

I'm betting that many local governments and corporations decided it was cheaper to take the chance on a failure rather than spend the money to detect and fix what might be a problem; and the dice has been rolled a few too many times.

I would not doubt it one bit.

MINNEAPOLIS ?- As cranes carefully began the process of removing cars, trucks and a school bus from the twisted concrete and steel wreckage of a collapsed Minneapolis bridge Sunday, divers found another body in the Mississippi River, raising the official death toll to nine.

Steel plates connecting beams in the Interstate Highway 35W bridge in Minneapolis were too thin by half and fractured, "the critical factor" in the collapse that killed 13 people and injured 145, the National Transportation Safety Board said Tuesday.

The connectors, called gusset plates, were roughly half the 1-inch thickness they should have been because of a design error, NTSB Chairman Mark Rosenker said. Investigators found 16 fractured gusset plates from the bridge's center span.

"It is the undersizing of the design which we believe is the critical factor here. It is the critical factor that began the process of this collapse. That's what failed," Rosenker said at a news conference.

What caused the bridge to collapse during rush-hour traffic in the early evening of Aug. 1 ?- "the straw that broke the camel's back," as Rosenker put it ?- is not yet known, he said. A final report by the NTSB is expected this fall.

[...]

However, the NTSB can't discount the possibility of similar errors in similar bridges, he said, adding that states and contractors should look at the original design calculations for such bridges.

The NTSB issued a safety recommendation to the Transportation Department's Federal Highway Administration suggesting that the agency require bridge owners to do so.

[...]

Abolhassan Astaneh-Asl, a professor of civil and environmental engineering at the University of California at Berkeley and an expert on gussets, spent 10 days in Minneapolis after the collapse gathering information.

"I concluded that the construction load may have been the last straw," he said.

The bridge was deemed "structurally deficient" by the federal government as far back as 1990, and the state's maintenance of the structure has been questioned. But Rosenker said the NTSB investigation has found no evidence that cracking, corrosion or other wear "played any role in the collapse of the bridge."