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Potential Flaw Found in Design of Fallen Bridge
NY Times ^ | August 9, 2007 | MONICA DAVEY and MATTHEW L. WALD

Posted on 08/08/2007 7:59:09 PM PDT by neverdem

MINNEAPOLIS, Aug. 8 — Investigators have found what may be a design flaw in the bridge that collapsed here a week ago, in the steel parts that connect girders, raising safety concerns for other bridges around the country, federal officials said on Wednesday.

The Federal Highway Administration swiftly responded by urging all states to take extra care with how much weight they place on bridges of any design when sending construction crews to work on them. Crews were doing work on the deck of the Interstate 35W bridge here when it gave way, hurling rush-hour traffic into the Mississippi River and killing at least five people.

The National Transportation Safety Board’s investigation is months from completion, and officials in Washington said they were still working to confirm the design flaw in the so-called gusset plates and what, if any, role they had in the collapse.

Still, in making public their suspicion about a flaw, the investigators were signaling they considered it a potentially crucial discovery and also a safety concern for other bridges. Gusset plates are used in the construction of many bridges, not just those with a similar design to the one here.

“Given the questions being raised by the N.T.S.B., it is vital that states remain mindful of the extra weight construction projects place on bridges,” Secretary of Transportation Mary E. Peters said in a statement issued late Wednesday.

Since the collapse, the concern among investigators has focused on “fracture critical” bridges, which can collapse if even a single part fails. But neither the safety board nor the federal Department of Transportation on Wednesday singled out any particular design of bridge in raising its new concerns about gusset plates and the weight of construction equipment.

Concerns about the plates emerged not from the waters of the Mississippi River...

(Excerpt) Read more at nytimes.com ...


TOPICS: Front Page News; Government; News/Current Events; Technical; US: Minnesota
KEYWORDS: 35w; bridges; civilengineering; collapsedbridge; designflaw; engineering; engineeringdisasters; minneapolis; ntsb
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To: neverdem
The Federal Highway Administration swiftly responded by urging all states to take extra care with how much weight they place on bridges of any design when sending construction crews to work on them.

Cool, I have a bridge crew out tearing up a bridge deck at this very moment. Tomorrow at 6 AM, they will finish up their workday, and I'll have 2 more crews working on differnet bridges. Yeah, we have to calc loads, but nothing exceeds the loading of an 80,000 lb. tractor trailer.

Woohoo, now everyone cares about bridges. Looks like I'll have job security until about christmas, when nobody will care any more.

41 posted on 08/08/2007 8:56:39 PM PDT by Clam Digger (NO REAL THAN YOU ARE!)
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To: crazyshrink
Bush was here on saturday to check his work and was seen smirking.

Friday, Laura Bush visited friend on Hennepin avenue before visiting with the MSM at the bridge. /s

42 posted on 08/08/2007 8:59:08 PM PDT by EGPWS (Trust in God, question everyone else)
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To: exit82

I have been reading your work on here before and find it very interesting. Thjank you for your insight. It has helped me to understand this.

From the video I saw, the center section just drops. First one side and soon the other. Once freed from the center section, the shore sections simply fall back on themselves pulling and twisting on the pilings on the shore on each side of the river. 1 of These pilings is only in the river when it is high.

My opinion only.


43 posted on 08/08/2007 9:01:16 PM PDT by crazyshrink
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To: TXnMA
They did not fall simultaneously. In fact, the north side didn't collapse until a full quarter-minute (15 seconds) after the south end started falling

I think he meant both sides of the roadway, not both ends of the bridge. It did look like both sides failed at the same time, the bridge didn't seem to twist much as it fell.

44 posted on 08/08/2007 9:02:42 PM PDT by El Gato ("The Second Amendment is the RESET button of the United States Constitution." -- Doug McKay)
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To: neverdem
Crews were doing work on the deck of the Interstate 35W bridge here when it gave way

How could this be? I thought Bush spent all the country's money on the Iraq war and there was none left for "infrastructure". Maybe they were volunteers.

45 posted on 08/08/2007 9:04:12 PM PDT by Mannaggia l'America
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To: Clam Digger
now everyone cares about bridges. Looks like I'll have job security until about christmas, when nobody will care any more.

Ah contraire for coal mines are the money grab in real time now.

46 posted on 08/08/2007 9:04:24 PM PDT by EGPWS (Trust in God, question everyone else)
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To: commish

Explain to me what you think they were doing dumping rock onto the bridge?

They were resurfacing the bridge. That means they were taking off a layer of rock and then removing the broken pieces. The next portion of the job is to lay a new layer of cement.


47 posted on 08/08/2007 9:04:57 PM PDT by trussell (Prayer is good for the soul)
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To: exit82
JUst to run with your opinion a little, and hopefully I am not too far into left field here -- what if there is a combination of all these factors working together to create a instantaneous catastrophic failure.

I can't fully tell exactly where in the center span all the trucks and rock we were discussing was, but IF it was all concentrated toward that south pier -- and the pier was possibly weakened by scouring -- is it plausible to suspect that the excessive weight concentrated in one spot may have placed stress on the pier in just the right angle or something to cause the pier to fail as you suspect -- or even if a gusset plate or a girder failed right there could that create the stress needed to cause the southern pier to shift and fail???

48 posted on 08/08/2007 9:05:11 PM PDT by commish (Freedom tastes sweetest to those who have fought to protect it.)
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To: trussell

Cement wouldn’t do much, it’s just a fluffy powder. :)


49 posted on 08/08/2007 9:05:52 PM PDT by Clam Digger (NO REAL THAN YOU ARE!)
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To: There You Go Again
>>>President Bush screwed up the design of this bridge.<<<

This is an obvious ploy by the Bush administration to foist the blame off on some poor underpaid state engineers. It won't work because everyone knows the administration has final approval of all state bridge designs.

America's lawyers and media would have you believe that every accident is an evil act perpertrated by the people that actually make our society work!!

50 posted on 08/08/2007 9:05:54 PM PDT by HardStarboard (Take No Prisoners - We're Out of Qurans)
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To: El Gato

I couldnt see both shore sides on the security video from the lock. The shore sides of this bridge were quite different. One had an off ramp (extra support) right at the shoreline. One side was higher up than the other.


51 posted on 08/08/2007 9:06:15 PM PDT by crazyshrink
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To: crazyshrink

I forgot to “sarc” it; next time.


52 posted on 08/08/2007 9:07:34 PM PDT by Atchafalaya (When you are there thats the best)
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To: trussell

The reports the last few days said the crew was jackhammering the concrete away, and then was applying a 2 inch layer of crushed rock that the new roadway would sit on — the reports specifically said 100 tons of crushed rock were on the bridge ready to be spread (or already spread - that point was unclear)


53 posted on 08/08/2007 9:08:00 PM PDT by commish (Freedom tastes sweetest to those who have fought to protect it.)
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To: There You Go Again
President Bush screwed up the design of this bridge.

What did design have to do with it? That Gusset plate went when the cruise missile hit!

54 posted on 08/08/2007 9:08:27 PM PDT by burzum (None shall see me, though my battlecry may give me away -Minsc)
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To: Mannaggia l'America
I thought Bush spent all the country's money on the Iraq war and there was none left for "infrastructure".

PSSST!

Don't tell anyone for it's our little secret but President Bush's tax cut's created more revenue than what raising taxes to pay for infrastructure has.

55 posted on 08/08/2007 9:09:34 PM PDT by EGPWS (Trust in God, question everyone else)
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To: burzum

hmm come to think of it — have they completely ruled out the Bridges center fuel tank exploding yet????? ;-)


56 posted on 08/08/2007 9:10:06 PM PDT by commish (Freedom tastes sweetest to those who have fought to protect it.)
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To: neverdem

“Bush was here on saturday to check his work and was seen smirking.”
He’s got his mother’s mug doesn’t he?


57 posted on 08/08/2007 9:10:42 PM PDT by ArtyFO (I love to smoke cigars when I adjust artillery fire at the moonbat loonery.)
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To: EGPWS

You mean MN’s 2.2 billion $ budget surplus this year was real? Sarc/off


58 posted on 08/08/2007 9:11:55 PM PDT by crazyshrink
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To: crazyshrink
>>>And as the article says, these gusset plates are used in bridges and structures of all kinds and sizes all over the country.<<<

I would bet there are thousands of rivited gusset plates in the Empire State Building and every other major building and bridge built before 1965.

59 posted on 08/08/2007 9:13:13 PM PDT by HardStarboard (Take No Prisoners - We're Out of Qurans)
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To: burzum
That Gusset plate went when the cruise missile hit!

I'll know that to be true when I can travel 35W instead of 280 and see a sign showing a cruise missile in a red circle with a line through it just before crossing the bridge.

60 posted on 08/08/2007 9:13:14 PM PDT by EGPWS (Trust in God, question everyone else)
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