NTSB: Design flaw led to Minnesota bridge collapse

[babylonsister]

updated 4:43 a.m. EST, Sat November 15, 2008


NTSB: Design flaw led to Minnesota bridge collapse


(CNN) -- Federal regulators said support plates that were about half as thick as they should have been were the likely cause of the August 1, 2007, bridge collapse in Minnesota that killed 13 people and injured 145.


Thirteen people were killed and 145 were injured in the August 1, 2007, Minnesota bridge collapse.

The gusset plates -- metal plates that are meant to strengthen joists -- are believed to have failed on the I-35W bridge over the Mississippi River in Minneapolis, Minnesota, causing the collapse, according to the National Transportation Safety Board.

There were 111 vehicles on the portion of the bridge that collapsed, dropping them 108 feet into the 15-foot-deep river.

An NTSB report released Friday said the board's investigation found that 24 "under-designed" gusset plates were not discovered in reviews during the bridge's design and construction. The bridge opened in 1967.

more...

http://www.cnn.com/2008/US/11/14/bridge.collapse/

[Deja Q]

1. When you design it, not thinking that in 40 years' time it'll get a lot more use from bigger trucks,

methinks there's a more compelling reason for the collapse...
:dunce:

Besides, the last I'd heard, on the radio, 3 days ago, was that placing too much weight in the vicinity, back when they were repairing the thing before the crash had taken place, was a contributing factor...

What next, they'll bring back that quaint theory that a bunch of pigeons started a war and took a collective dump on said gusset plates; the subsequent formation of rust corroding and weakening them to the point of disintegration?! Yeah, that's the ticket...

[mn9driver]

2. The NTSB has been politicized like every other govt agency.

The gusset plates were undersized? Ok, fine.

There are photographs of these gusset plates taken by bridge inspectors in 2003 that CLEARLY show that they are bending and deforming under the load. I invite any structural engineers here to step in and tell us whether that might or might not be a MAJOR ALARM BELL that something was seriously wrong with this bridge---more than four years before it finally fell:

http://minnesota.publicradio.org/display/web/2008/03/24/bridgeinvestigation/?rsssource=1

The NTSB has brushed EVERYTHING else away, saying that only the design flaw, and nothing but the design flaw is responsible for this, even though the bridge stood for 40 years before it collapsed. I have never seen an NTSB investigation that completely ignored contributing factors like this one has. It is a basic, basic tenet if mishap investigations that there is a "chain of events" that leads to something like this. The NTSB has decided that this particular 40-year-long chain has only one link.

It is bizarre, ridiculous, and another indication of the kind of house cleaning that has to happen to make the government function properly again.