Federal investigators say design error, too much weight doomed I-35W bridge [Minnesota]

Pioneer Press ^ | 11/14/08 | Jason Hoppin

[Enchante]

WASHINGTON — The Interstate 35W bridge collapsed because of forces so great a massive piece of steel was stretched as if it were latex, eventually ripping apart and causing one of the biggest transportation disasters in U.S. history.

Holding the first of a two-day hearing before it releases final findings and recommendations, the National Transportation Safety Board said Thursday the collapse in Minneapolis was caused by a fatal design error. The error allowed an accumulation of weight added to the bridge over its 40-year lifespan — plus the weight associated with a new construction project — to finally topple it, killing 13 and injuring 145.

"On the final day, the day of the collapse, there was this concentrated location of construction materials and equipment on the bridge. And all of those things combined to overload the gusset plates and cause the collapse," said Carl Schultheisz, who conducted a sophisticated computer analysis of the collapse for the NTSB.

The NTSB cited a number of factors contributing to the overall weight on the bridge, including a new layer of concrete added in 1977 and new medians added in 1998. The federal investigators said summer heat and rush- hour traffic also could have stressed the bridge's steel gusset plates.

While the NTSB stopped short of saying what actually pushed the bridge past its breaking point on the evening of Aug. 1, 2007, it did say that the more than 250 tons of construction materials and equipment were a significant factor, while ruling out rust, maintenance problems and even terrorism.

[Enchante]

NTSB rules out maintenance issues - says collapse of I-35W bridge was due to fundamental design flaw plus amount of weight (250 tons) added to bridge for construction project.

[Enchante]

Wow, and I thought the bridge collapse was entirely due to President Bush and the Iraq War..... at least that’s what the libs were saying at the time.

[ButThreeLeftsDo]

Lack of taxes in Minnesota brought the bridge down.

That will never happen again.

Because taxes in Minnesota will explode in the next four years.....

[pankot]

250 tons too much? Even a freshman in engineering knows you design with a safety-factor. Shoddy design or someone was cutting corners to save a buck likely cause.

[Nathan Zachary]

How does a bridge accumulate weight over 40 years. does it grow, get fat like all Americans?

If it overloaded the gusset plates, then surely regular maintenance would have spotted it. Sounds like crappy maintenance to me, along with oversight engineers not doing their job when it was built in the first place.

[Spktyr]

Bookmark for later.

[gogov]

[Nathan Zachary]

Lack of government doing their jobs, just rubber stamping projects without bothering to inspect blueprints, looking for exactly these things. That's what they blow fortunes on engineering consultants for every year. Guess they "missed" this one, or something a little more shady

National Transportation Safety Board said Thursday, shifting blame as far away from themselves as possible.

[Enchante]

Well I’m no engineer but what I took from the article is that in 1977 and 1998 they added weight with concrete and then medians, but presumably if they had understood the initial design flaw with the gusset plates, they would have realized that the bridge was flawed and certainly shouldn’t have any weight added?

I don’t know how regular maintenance would catch a problem that had to do with the original design specs (unless the gusset plates went bad slowly and it should have been detected, but the article makes it sound like the crisis was sudden). But as I said I claim no expertise here at all............

[proudtobeanamerican1]

This interview took place at 5:00 p.m. on August 1, 2007. Exactly 35 minutes later at 5:35 p.m. the bridge collapsed. This Keith Ellison is a democrat from the Minnesotta district where the bridge was located. He was sworn in on the Koran and has defended Calypso Louie. From the International Herald Tribune http://www.iht.com/bin/print.php?id=6948843 Only Muslim in US Congress to return to Israel in group meeting with Palestinian Abbas The Associated Press Wednesday, August 1, 2007 WASHINGTON: The only Muslim member of Congress said Wednesday he will return for a second visit to Israel during this month's congressional recess. Rep. Keith Ellison, a first-year Democrat in the House of Representatives, will travel to Israel with about 20 other Democratic lawmakers on a trip sponsored by the American Israel Education Foundation. The foundation in an independent, nonprofit charitable organization affiliated with the America Israel Public Affairs Committee, or AIPAC, the pro-Israel lobby. In an interview, Ellison noted that much has changed since his last trip to Israel in the spring with a congressional delegation led by the top House Democrat, Speaker Nancy Pelosi. A Palestinian national unity government was dissolved after Hamas seized power in the Gaza Strip, while Palestinian President Mahmoud Abbas, who leads the rival Fatah faction, formed a government on the West Bank. This month's delegation, which will be led by House Majority Leader Steny Hoyer, will visit with Abbas in the West Bank but not with members of Hamas, which the United States considers a terror organization. The Muslim congressman said one message of his trip will be to promote dialogue. "I'm a firm believer that dialogue never hurt anybody � the cost of dialogue is very low," he said. "It's the best way to solve a problem." But asked if that dialogue ought to include Hamas, Ellison tread carefully. "Whenever you're talking about dialogue with Hamas, it's something that's extremely controversial," he said. "I'm not trying to step into some controversy, but I am trying to be a voice for dialogue. "I'm trying to go there to be a helpful figure, not a person who's going to stir up controversies." The delegation, geared to first-term members of Congress, also will meet with Israeli Prime Minister Ehud Olmert and other Israeli and Palestinian officials, academics and journalists. They plan to visit areas including the Golan Heights and Israeli border areas with Jordan, Lebanon and Gaza. It will mark Ellison's third trip to the Middle East this year, after a trip to Iraq last weekend. The American Israel Education Foundation also is sponsoring a separate trip of Republican lawmakers to Israel, said AIPAC spokesman Josh Block. The foundation organizes the first term-oriented trips every other year. "They meet with a very diverse group of people who represent opinions and views across the political spectrum in Israel, and a diverse group of representative views among both Israelis and Palestinians," Block said. He estimated the cost at about $5,000 (�3,660) per member.

[Nathan Zachary]

bridges of that type, where all the load is carried on those gusset plates aren’t all that complicated. That is the first thing you look at, calculate your loads, and beef up your steel load bearing plates accordingly. Those joints also expand and contract, so they are inspected and cleaned regularly, or are supposed to be, and checked for even the tiniest indication of stress.

You are exactly right, curbing being added should demanded that the specs be re-examined to see if the extra weight was safe with maximum traffic wieght figures.

[Nathan Zachary]

And with all that extra concrete and curbing, there should have been plenty of sign that the bridge was at it’s limits.

250 tons of extra weight isn’t a whole lot. less than 10 semi trucks crossing at the same time. which would be fairly regular traffic.

[proudtobeanamerican1]

http://www.frontpagemag.com/Articles/Read.aspx?GUID=9422068B-1775-43F8-A424-793655F91D86

This is also very interesting. Seems like he will be a key player with Obama.

[Smokin' Joe]

Nothing like travelling across a low-bid item...we do it with amazing regularity—like riding in an elevator in a government building.

[proudtobeanamerican1]

http://www.frontpagemag.com/Articles/Read.aspx?GUID=3A78305E-B13D-44A4-B452-A7166532ACC7

More Cair, Muslim Brotherhood and Ellison

[brityank]

Ping to you for verification of your well-done analysis, jeffers.

But questions remain about the collapse, including why the St. Louis-based company that designed the bridge used gusset plates — the large steel plates than connected the bridge's lattice of steel beams — that were too thin at more than a third of the span's critical locations, underscoring just how flawed Bridge No. 9340 was from the day it opened in 1967.

At some gusset locations — including at a gusset plate known as U10 West, the location where investigators suspect the collapse began — the half-inch steel was half as thick as it should have been in order to withstand the forces acting upon it.

Investigators for the NTSB, which had previously said it was focusing on the interaction of a flawed design and too much weight, displayed a computer model of the U10 West location showing what they believe happened. With too much weight pushing down on a critical connection, a diagonal beam began pushing out against a gusset plate that was already under tremendous stress. It began to flex until finally snapping, triggering a massive chain reaction that brought the entire bridge crashing into the Mississippi River.

[UnbelievingScumOnTheOtherSide]

...underscoring just how flawed Bridge No. 9340 was from the day it opened in 1967.

And in 1967, the President was a
DEMOCRAT!
(Anybody notice the similarity with the delayed-reaction banking crisis? With 9/11?)

[Right Wing Assault]

Meanwhile, a similar bridge in Cleveland is in trouble:

http://blog.cleveland.com/metro/2008/10/how_serious_are_the_inner_belt.html

http://blog.cleveland.com/metro/2008/11/plain_dealer_review_finds_odot.html

http://blog.cleveland.com/metro/2008/11/inner_belt_truck_ban_to_begin.html

[jeffers]

I thought, and still think that U10 East failed first, since the bridge had to sag lower and quicker to the east, early during the failure sequence, to fall sideways to the east as the post collapse images show.

It is quite possible for buckling or even fracture to occur first at U10 West, overloading U10 East, and triggering the precise failure sequence we got, but we’re talking milliseconds of difference in timing, structurally, those two sets of plates are coupled to the Nth degree.

However, from a semantics point of view at least, the bridge “survived” any possible U10 West failure, if even for a fraction of a second, and the U10 East fracture was the critical one, as it was the failure that most affected the final disposition of the debris.

Put as simply as possible, U10 West may have fractured first, but it was largely still doing its job, holding up the West Truss center span, when U10 East failed completely, letting the East Truss drop and twist both trusses to the East.

[downwdims]

I was on that bridge 3 days before (stuck in traffic) it went down. Unless the stuff was delivered after I was on it there wasn’t 250 tons of construction equipment on it.