Bridge Collapse in Minneapolis MN

[Thes Hunter]

Talking about why the DOT didn't have the money to fix the bridge, and where it could have gotten the money begins to float into the arena of political discussions. Which means I have much to bite my tongue about on this.


As for the extreme temperatures, as I am sure other Mid-westerners will chime in on... HELLS YEAHS.

It can change 30 degrees (or more) in just 24 hours. It's all because there is no geography impeding air flows either from the Gulf of Mexico, or for the Arctic. So depending dynamics of the jet stream and the high and low pressure systems... the temperature across the Mid-West will vary wildly.

I have a good experience of this growing up in Michigan, and we had just a wee bit of water sitting round us to act as a buffer.



"For those non-North American types, Michigan is the mitten looking one in the middle of the big land mass with all those 'Great' lakes around it.

[Chris the Pontifex]

Talking about why the DOT didn't have the money to fix the bridge, and where it could have gotten the money begins to float into the arena of political discussions. Which means I have much to bite my tongue about on this.

Yeah, you're right, sadly its politicians spending the money, not engineers. I've been doing much tongue biting about this already.

[CrazedGoblin]

is it just me or does the advert for life insurance on that news page showing a disaster with multiple fatalities just ring out as an "Only in America!" type thing?

[Zar Peter]

In austria we had the same picture of the bridge with advertisings about car insurrance.

[Oeep Snaec]

One of the people that died may have lived in my house before we (my family) did. Also, one of my neighbors is investigating why it happened.

In response to Chris' comments, there were many bridges that were deemed at higher risk than 35W. The varying amounts of traffic is taken into account when bridges are inspected. That was the main reason for not taking immediate action. Though he is certainly correct when he speaks of money control. NBC nightly news said the cost of repairing all the bridges in America would cost $65 billion. scrubbedOur whole infrastructure needs an overhaul.

[WampaX]

Voice of the Wampinator: As has been mentioned before, keep the topic clear of politics.

[Syka]

I'm glad to hear all the board members are ok.

As for those ads, I think they're tailored to hit on key words on pages. Like, on Myspace I get a lot of ones for anime and horror stuff. So having several mentions of cars and accidents is going to trigger an auto insurance ad. :) At least I think that's how it works.

Cheers,
Syka

[Samiam303]

I'm actually in Minneapolis myself for the week, so I was rather shaken at the news. Luckily all my MN-area relatives are alright, and surprisingly it sounds as though almost all the victums are accounted for and very few people are critically injured. Nonetheless, my thoughts go out to everyone involved.

[Rockphed]

"For those non-North American types, Michigan is the mitten looking one in the middle of the big land mass with all those 'Great' lakes around it.

I assume by "great" you mean Greatly Polluted and full of mutated, almost-sentient creatures.

In response to the bridge failure, Michigan has done a reassessment of its bridges, and come up with 9 counties with at least 1 in 4 bridges not meeting safety standards. Yikes!

[Vuzzmop]

That was a bit too soon. Anyway, I'm sorry to hear about the tragedy, and I'm glad to hear that all who have posted are okay. Good luck, as I can offer little else.

[Jimorian]

Of course all of this is wild speculation, I know nothing of the bridge's actual design and investigation of the failed members and joints should yield (engineering pun intended) more info.

My own bit of wild speculation: The paving crew on the bridge at the time seems suspicious. NOT because of the weight of any equipment, pavers are fairly small as far as equipment goes, and even a half dozen cement trucks waiting around to fill it up wouldn't be anywhere near the capacity of the bridge, even if bunched up in one spot.

What I'm more curious about is the nature of the action of the paving machines. If there was any kind of back-and-forth motion as part of the spreading/smoothing of the pavement mix, this could have set up a sympathetic vibration in the bridge. The word "Harmonic" is something that will give engineers nightmares because it can cause small forces to build up to devastating consequences. It's not a joke that a marching column of soldiers will mix up their cadence when crossing a bridge.

Add in the propensity for cracks already seen via the regular inspections, and you can see a possible sequence of events.

1) a small crack in a vital area that would probably get caught in the next inspection and shored up, is present.

2) the paving equipment is working and has a frequency that leads to a harmonic buildup of motion.

3) Cracked area is subjected to more flexing than it can handle, so it grows quickly and reaches a failure state.

There's a book Why Building Fall Down that I bet is going to get a lot of attention in the coming weeks.

Terrible tragedy.

[bosssmiley]

Scrubbed.

Unfortunately Tannish2, people regularly can and do put a monetary value on human life. That's the whole basis of life insurance. It's how you get bad jokes like the climax of "Death of Salesman", when the lead character works out he's worth more dead than alive. It's part of the calculus of living in an unpredictable and risky world:

"X action has Y risk of Z consequence. Is the payoff from X worth more than YZ? If yes, then do X."

You remember that scene in "Fight Club" with the "...take the number of vehicles in the field, A, multiply by the probable rate of failure, B, multiply by the average out-of-court settlement, C. A times B times C equals X. If X is less than the cost of a recall, we don't do one..." monologue: all true.

Maintainence engineers, being pretty straightforward, professional guys with brain in their head, usually spot problems before they happen and notify their beancounter bosses, who then run the numbers through their personal A x B x C = X spreadsheets. It's the beancounters - who've likely never seen the problem in anything other than the abstract - who make the decision on whether funds for repairs are released to the guys on the sharp end. They don't see the gaping cracks weathering in a harsh climate, just the probabilities flickering on a screen.

Those on the ground don't have the authority. Those with the authority haven't seen the problem for themselves. Result: dissociation from the problem, and a whole new field for Murphy's Law to play in. Unfortunately that is the necessary downside of the division of effort required to build, run and maintain our marvellously complex industrial society. When the system works, there's none better that we've ever found; but when it fails people can, and do, die needlessly.

I'm sorry if the above post sounds cynical to you. It really isn't. I feel for the people who's lost relatives in a senseless accident, but I don't want people to assign blame and find scapegoats in the wrong places.

[Miklus]

It must be very frustrating being a structual engineer responsable for bridge maintainage. You write a nice report on how delapidated the bridge is, and it is promptly ignored.

There was on thing the poor engineers could have done: Shut down lanes. There was, what, four lanes each way? Shut down one or two lanes due to "safety reasons". Traffic jams will insue. People will be pissed. And the politicians will suddenly find the money!

That's what I would have done anyway. Yes, the politicians might see this as a critisism of the budget and claim that I take the public hostage. They might even threaten to fire me, but I would just say "Sorry, I must follow procedure! Safety rules are safety rules. You're not suggesting that I break the rules, do you?"

[EmeraldRose]

Two lanes each way were shut down at the time of the collapse. This could have been much worse than it was. Also, the fact that noone was really moving...during rush hour, traffic doesn't move much...it could have been going 70 MPH (more than 112 KPH) or more...

[Miklus]

Aha, I see now that they where, in fact, doing some repairs when it collapsed. A little bit to late...or maybe the repairs was a factor in the collapse. Bridges and buildings often collapse during construction and renovation (that is, if they collapse at all, of couse).

I do note, however, that this seems to be a case of progressive collapse. One section falls, and the entire bridge collapses, even quite far up the banks on either side. It could have been designed better, methinks. Girder bridges don't take damage very well. There is no redundancy.

I wonder who looses "The Blame Game". Some engineers are already covering their butts. The politicians won't loose, they are too good at this game. I guess the construction firm doing the repairs gets to take the fall.

[Mad Wizard]

I was actually at the Guthrie Theater when the collapse happened, and I could see it from there.

[Chris the Pontifex]

I do note, however, that this seems to be a case of progressive collapse. One section falls, and the entire bridge collapses, even quite far up the banks on either side. It could have been designed better, methinks. Girder bridges don't take damage very well. There is no redundancy.

not all girder bridges do. welded tubular members would have taken this a lot better. plus, architects like them. then again it would have been more expensive... but easier to maintain... Seemingly the engineers at the time thought it was a good idea to use as little steel as possible, and they did a fine job doing just that.