35W Freeway Bridge Collapse

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Considering what they knew

CNN is reporting:

"A 2001 study conducted by the Minnesota Department of Transportation found "several fatigue problems" in the bridge's approach spans and "poor fatigue details" on the main truss.

The study suggested that the design of bridge's main truss could cause a collapse if one of two support planes were to become cracked, although it allowed that a collapse might not occur in that event. But, the study concluded, "fatigue cracking of the deck truss is not likely" and "replacement of the bridge ... may be deferred."

Two years ago, the U.S. Department of Transportation's National Bridge Inventory database said the bridge was "structurally deficient."

The Minneapolis Star Tribune quoted Jeanne Aamodt, a spokeswoman for the Minnesota Department of Transportation, as saying the department was aware of the 2005 assessment of the bridge.

The bridge received a rating of 4 on a scale of 1 to 10. A bridge receives a rating of 4 when there is "advanced section loss, deterioration.""

Somehow I don't understand "could cause a collapse" and "replacement of the bridge ... may be deferred." within the same report. The over due bill for the repairs and replacements required in this country is truly staggering, but as long as we insist on further tax cuts, and securing oil sources in hideous parts of the world, the deterioration will continue.
 
Robert, I got into my car after getting a haircut yesterday evening, turned on the radio and heard about the bridge and immediately thought of you. I haven't even met you but through this site it feels like you are a part of my circle of friends. I have not had access to a computer until now and was glad to see your quick post advising us that you guys are both OK.

It will take a while for the numb feeling to go away. Like Rich said above, this is reminiscent of the Cypress structure collapse on the 880 freeway in Oakland back in 1989, and the images will stay with you forever.

You will definitely be in my thoughts as this tragedy continues to unfold.

Ralph
 
20 to 30 people still missing

Imagine the fear and the horror, theirs and the people who watched the road they were driving on fall into the river as their cars followed. And the terror and sadness of all of our friends who live in the area and must deal with such a tragedy. It would be the same as if the Peace Bridge fell into the Niagara River. Unimaginable! Everyone would know someone involved.

And Robert working a half mile away--this scares us half to death.

So relieved that you're all safe. But those missing people, still under water---God help them and their loved ones.

Sending my heart out to my magnificent friends in Minneapolis,

Michael

XXOO
 
When I heard of this disaster, I just couldn't stop thinking about Robert, Eugene, and all of the other members who might have inadvertantly been endangered by this disaster, and it really came into my heart how quickly all the little resentments and squabbles disappear when you realize that life is at stake.

The only thing positive I can think of is to just ask forgiveness of any members I may have offended in the past, and mention how glad you folks are a part of this online community, and how much I've gotten from "knowing" all of you.

In regards to the bridge....yep, the deterioration of our vital infrastructure is a HUGE problem here, because our city is so old.

I think we as a nation have to begin paying more attention to this, even if the Minneapolis bridge disaster proves to be from other causes (or, as Toggle mentioned, a combination of factors).

The rust on the bridge in that picture is nothing compared to the disrepair on some of the beautiful old bridges we have here, and it's always better to preserve and restore in advance than it is to have to just junk the old structure and live without it, until some cheap thing (that costs a lot of money anyway) is thrown up.

I also believe that the weight of our vehicles and trucks is a problem. A lot of these structures simply weren't meant to hold our behemoth vehicles suspended in midair, especially when they sit for extended periods of time in our epic traffic jams.
 
I am convinced I will be perfectly fine in life, because:

~It could have been a whole lot worse......
See the link- thank God it wasnt 10 seconds before!(see the bit about the School bus!)

G-d protects fools and children.

When your time is up and your number is called, there is no denying it or avoiding it. Worrying solves nothing.
 
Back 40 years ago when this bridge was built, cars were bigger and heavier than they are now. I don't think this was an issue of too much weight. With 2 lanes closed in both directions, even the construction equipment sitting on the bridge wouldn't likely add up to the weight of 4 lanes worth of stopped traffic.

If it had been the George Washington bridge that failed, I wouldn't have been surprised at all. I have never been on a bridge in a worse state of repair, at least where the roadway itself is concerned.

15 years ago Bill Clinton was talking about infrastructure and it appears that we are still in a situation where nobody feels any sense of urgency. Maybe this tragedy will get Congress moving but with Bush siphoning every last dollar to fund his misguided war on terror it will be hard coming up with the billions that will be needed.
 
Between this bridge, the steam pipe explosion in new york and i think there was something else, i hope some peoples gets off there butts and starts fixing up the infrastructure..
 
I had been trying to think of something else recent too, but
the only thing I found that seemed similar was the bridge
collapse in CA when a tanker truck ran into it?
 
Yes, but collapse on 880 in Oakland due to the tanker truck fire was an elevated section of roadway in the same area as the Cypress structure that collapsed as a result of Loma Prieta back in '89. Different construction than the 35W bridge but still created a traffic calamity. The 880 was fixed in less than a month by a construction company that has a reputation for getting things done ahead of schedule. It's going to take much longer to replace an entire bridge. The commuters in the Mpls area are going to be dealing with a long term traffic migraine as a result of this incident.
 
True. The tanker truck fire caused the steel in the 880/580 interchange overpass to soften and fail. This was a similar effect as was seen in the WTC when the intense heat of the burning jet fuel caused the structural skeleton of the towers to fail. The steel didn't actually melt, but, rather, the heat caused it to change its internal crystal structure to a form that has much less tensile strength than at room temperature.

There was no such heat related failure in Minneapolis. Of course the real cause isn't known, but I suspect corrosion, plus the possibility that the reinforced concrete roadway was actually the only thing holding the structure together (which it wasn't designed to do). When they started working on the expansion joints in the roadway, under the assumption that they had nothing to do with the structural integrity of the bridge, the structure's developed weakness was exposed and catastrophic failure ensued. Just a theory, but it seems quite possible to me at this time.
 
We'll just have to wait and see. Apparently they are going to recover as much of the bridge as they can and reassemble it in a different location just like with aircraft accidents to determine the cause.

A not so comforting statement from a structural engineer at the U or M..

"Baffling. Sudden death of a bridge. As if a 50-year-old man with no prior health issues suddenly dropped dead while walking down the street.

These are the descriptions just given to me by Dr. Ted Galambos, emritus professor of structural engineering at the University of Minnesota. Galambos, the man I went to for answers on why this bridge collapsed, actually had none.

Galambos says the bridge design, its structure and its four decades carrying traffic over the Mississippi, make what happened here yesterday virtually impossible.

I asked all the questions: Cracks in steel? Construction accident? Salt corrosion?

Galambos says anyone of them can bring down a bridge-but not like this. It was complete and instant failure. Cracks and corrosion give warnings, construction accidents can be witnessed. There is no evidence, he says, of either.

The surveillance video seen on CNN shows an event he calls one-in-a-billion; it just doesn't happen.

And yet it did.

We of course are searching for instant answers. Dr. Galambos says the methodical piecing together of how the bridge collapsed will take time and much patience. He is 78-years-old. He told me he hopes to live long enough to learn the real cause."
 
What Billions of Dollars Could Have Been Better Spent On...

In addition to my earlier comments: Look what all these billions of dollars could have been spent on besides this long drawn out war in Iraq.--Laundry Shark
 
I'll probably be in minneapolis in the next few weeks with my sister and her kids... Don't wanna go into all the details here, but her best friend, husband and kids where involved in this catastrophe, she works several blocks from here and travled that way daily.. They where just moved there because his job transferred him there... Its not all roses for them right now.. She quit her job today and is coming back to Baltimore with the kids.. Her husband isn't..
 
BTW He is not deceased... SHe is leaving because of him and this catastrophe was the last straw.. She lost there brand new Mercedes last night and he was far more concerned over a $45,000 car than his family
 
You don't know what you've got 'til it's gone...

Was worried when you said "he isn't.." - whether he's a jerk
or not.

Bit confused, the police now say 4 persons died, still 20
missing, 78 injured. Last night they were saying 6 and then
7 had died? Of course the missing number is not encouraging.
 
What Billions of Dollars Could Have Been Better Spent On...

Laundry Shark

Nightly News just said it would cost $65 billion dollars to
repair the 13% of bridges that are structurally deficient.
Definately cheap in comparison to a trillion dollars wasted.
 
Thank goodness

Very good news this evening. The latest information is that the death toll has dropped to only 4 and now only 8 people are unaccounted for down from 30, so this is very good news indeed. It is just amazing looking at those picture that more people did lose their lives in this disaster.

Chad, do not do this here, not in this tragic thread. There is still a lot of us here who remember you from back in the days of the old Yahoo Appliance Club, and the lies you were caught in, I can and will post links. This is your one and only warning and I mean it.
 
Interesting like-minded professors

The guy on the PBS News-hour, a prof from Cornell, said that the chances of a bridge like that collapsing are the same as the chances of winning the lotto after purchasing one ticket.

Not to be overbearing, but you are so robustly and vibrantly healthy and so non-stop active that I never once thought of anything happening to you. What would happen to AWORG if anything ever did????????!!!!!!!!!!!!

EXAMPLE: You went right to the U of M to get an answer from the expert--Perfectly and Classically Robertine.
 
Robert,

Thanks for the update on the possible causes of the bridge collapse. The analogy to a 50 year old man dropping dead for no apparent reason is interesting. Here in SF we lost a long-time local newscaster. He was in his early 60's and going in for a second hip replacement. All his pre-op tests were normal, including cardiac, but 30 minutes after he went under general anesthesia he had a massive heart attack and died. It turned out he had badly plugged coronary arteries, but these didn't cause any symptoms and were not detected by the usual tests (only an angiogram - expensive and somewhat risky) would have shown that.

What the 10th Street Bridge needed was the civil engineering version of an angiogram. No doubt there are other bridges in similar need of more close scrutiny.

I did hear on some newscasts reports from eyewitnesses - perhaps the construction crew - that just before the collapse someone remarked that things were not "right". I just saw the CNN/surveillance video of the collapse and it does appear that the middle section of the bridge simply collapsed - both ends going at once. Very puzzling.

Earlier I stated that Homeland Security had ruled out terrorism. That was what I'd heard on TV initially, but that was amended to that HS has said they haven't yet found any evidence of terrorism. On the other hand, there was no explosion and no terror group has claimed responsibility, so I still think it's highly doubtful this was more than a structural failure.

I'm not a structural engineer but it seems to me that the type of construction of this bridge has some inherent weaknesses. I supppose every man-made design has some compromises, but I don't think we'd find a structure like that bridge anywhere in California, where it would not meet seismic safety codes. Particularly that the entire center span rests on four rather spindly looking concrete posts.

But you're right, time, a careful reconstruction of the debris, and professional analysis will ultimately solve this puzzle. And no answer is going to bring back the dead or reverse the injuries of the people who were on the bridge. But it might help prevent more people from suffering in another bridge collapse.
 
Very few bridges built in '67 would meet current seismic codes; the codes have been upgraded significantly since then, especially after the '73 Sylmar quake, Loma Prieta, and then Northridge.

I think it is pretty evident that at least some of the bridge's structure wasn't supporting the design load, which resulted in the rest of the structure becoming overloaded. That is the way sudden, catastrophic failures like this usually happen. The big question now is what caused the structure to become so unevenly loaded. My guess is that corrosion might have played a big part, possibly exacerbating metal fatigue.

One thing to remember is that as computer analysis became more available and steel alloys got stronger structural engineers were able to design safer and more efficient structures. The downside to this over older designs is that the older designs may be more overbuilt and have steel that is less efficient but more resistive to corrosion. In a way this may be a bit analagous to old cars: the really old ones built before the '70s can often rust a lot before they get dangerously weak, but there were huge problems in the '70s with new and thinner steels. That is why cars are now so well protected from corrosion because the high-strength steels just don't have the thickness to handle extensive rust.

It is really heartening to hear that the number of fatalities has been downgraded. We can only hope that this catastrophe will be a wake-up call to the seriousness of extensive deferred maintenance of infrastructure in this county. It isn't about prettiness, it's about keeping our world safe to use. Roads and bridges were supposed to be maintained by highway funds paid for by our fuel taxes, but those monies have now been highjacked for all sorts of other uses and at some point it is government (either local, state, or federal) which must take the blame for this.
 
Minnesota folks, I could not click the buttons on the remote control fast enough tonight, to get additonal info. So happy to see your posts. All of YOU and your community are in my prayers. alr2903
 
Very few bridges built in '67 would meet current seismic

True, but I just watched a UC Berkeley engineering professor interviewed on TV, and he stated that there are no bridges in California of the same design as the collapsed Minneapolis bridge. I doubt that design would have met California seismic standards of 1967 either.

Not only high strength steels but also more advanced engineering analysis has enabled the design of structures with less overall material. This means less static weight, and further reductions in material may also have been made to take advantage of that. It's a law of diminishing returns - where the lighter construction means that load limits must be much more carefully observed. It seems like the 10th Street bridge was built to the "lighter, better" philosophy, which I think was also part of the '60's thinking for many products (for example, "Danish modern" furniture vs. much heavier overstuffed older but perhaps sturdier traditional designs).

There is also the disconnect between engineering and execution. I think a famous sports dome collapsed a few decades ago because the carefully planned design was misinterpreted and parts didn't fit right. The construction crew used brute force to make it all fit, and the eventual result was a disastrous collapse. Then there are the dishonest contractors and suppliers who cut corners and supply inferior key parts (like bolts and pins) that may fail and cause disaster. As I recall there was a famous collapse of a balcony inside an Hyatt Hotel atrium that resulted in many deaths, and it was traced to shoddy construction execution. Part of this problem may be that older construction bosses may not fully realize that newer designs rely upon top quality materials, and that what they were able to get away with in the past no longer works with newer designs.

Thinner steels surely do have less mass to resist rust, but they may also be more inherently rust resistant thanks to the presence of alloying elements. But the slightly increased rust resistance may be minor when compared to truly rust resistant alloys like 304 stainless. Impurities in the steel may result in a greater tendency to corrode; I've heard that many cheaper European cars of the 70's (think FIAT) were rust buckets in part to their use of inferior but cheap Soviet supplied sheet metal. Of course, proper metal prep, primer, and paint plays a very big role as well. The advent of zinc-rich primers in the 90's led to greatly extended rust-through warranties on new cars. The downside is that newer more eco-friendly water-based topcoats didn't stick to the zinc-rich primers very well, and often failed after a few years... leaving a formerly attracive car look like it has some horrible skin disease (topcoat paint peels off in sheets, leaving dull gray zinc primer behind).
 
Robert,
Interesting thoughts from Dr. Galombas. He sounds like a very interesting person.
When I saw the video of the bridge falling, I was shocked at how "even" the fall was. In videos that I have seen in the past of bridge failure, it always looked as though it was twisting on one side before the entire collapse. Unless I am not seeing something, this looks like a straight fall.
I agree with the Dr. that you talked to, it will take lot's of testing to see why.
I also think of the bridges that I grew up around in Louisiana, and am amazed that they are still standing. Huge structures, that I was always scared to drive across. Reasons were of age, and TONS OF RUST!
Time will tell about the bridge structures in the US.
I am also thankful that there was not more deaths than reported yesterday.
You just never know what can happen.....
Brent
 

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