Bridge collapse in Minn

[legion]

Originally Posted by slakjaw

In my line of work I have been to many places and mpls has the worst roads I have ever driven (inside the USA) I am just furious, we pay the second highest taxes in the nation and it takes months to fix potholes on I-94 or anywhere else. IMO neglect is what caused this.

IMO, the higher the taxes, the more "other priorities" a government entity has. Surely you wouldn't argue that crack-addicted illiterate juvenile delinquents don't deserve free room and board more than you deserve decent roads (and other basic services)?

Everytime I hear of a big, new government program, not only will my taxes go up, but it will get the focus over traditional government functions.

Chicago's solution has been to make the rest of the state pay for its infrastructure so that it can focus on "what is really important".

[Aerkuld]

I have great sympathy for anyone affected by this. It is shocking to think that this structure was inspected and a warning was given which was not acted on, which appears to be the case. If what we are hearing turns out to be true a 'structural collapse due to budget failure' should be listed as the cause and I would want to see the persons responsible for this locked up.

[competentone]

Originally Posted by CurtEgerer

The current construction activity looks to be repaving only. If that's the case, the only potential problem would be unusual loading conditions. Were they stockpiling paving material on the bridge? Did they have heavy equipment concentrated in one area?

Good questions, but I wouldn't say the "only potential problem" would be unusual loading.

I've heard reports that they were running jack-hammers. I would assume they were breaking up concrete. I wonder how many were being used and the time-frame of their use in relation to the collapse? One cannot ignore the possibility of destructive resonance weakening the structure and contributing to the collapse.

[kstar]

Here's some video from a security cam of the collapse:



FYI.

Kurt

[Porsche-O-Phile]

Wow - just nuts.

My old office had an entire division dedicated to transportation (among other things, they were on the approved designers list for Illinois DOT, not sure about Minnesota, but we had an office there, so maybe...) Anyway the guy who used to sit next to me was a transfer from Chicago - civil engineer. His role back there used to be bridge inspection as well as some roadway design, but he used to tell me horror stories about some of the stuff he'd find on bridge inspections. Apparently the freeze-thaw cycles in the Midwest are very hard on stuff and as usual, the high-$$$ maintenance costs are a political football (most politicians try to push it off onto the next administration or whatever).

Yet another shining example of misappropriation of tax dollars - untold billions to rebuild I-Wreck while our own infrastructure crumbles under us. Very nice.

[legion]

There is no political glory in maintaining infrastructure. But a government-funded health insurance program for the children? (Think of the CHILDREN.©) That's the kind of thing political legacies are built on.

[competentone]

Originally Posted by kstarnes

Here's some video from a security cam of the collapse:



FYI.

Kurt

That is some fantastic footage. It actually looks like the video is edited to start after failure of some of the beams has already occurred. They look twisted at the very beginning of the video. No doubt that video will play a significant roll in determining the exact details of the collapse.

[CurtEgerer]

I highly doubt a standard 60 or 90-pound jackhammer on the pavement could have triggered this (unless the deterioration of the steel framing was incredibly severe). Compare that to the resonance from, say, several fully loaded semi-tankers or cement trucks bouncing across this thing at 70MPH day in and day out. But who knows at this point? If there were, indeed, "out-of-plane girders" all normal assumptions can be thrown out the proverbial window.

[CurtEgerer]

I don't think that video is going to help much other than verifying that the collapse started on the same side of the river as the camera location which I think is pretty obvious anyway. Unfortunately the steel pier structure that will be the focus of the investigation is just out of view of the camera on the right side.

[competentone]

Originally Posted by CurtEgerer

I highly doubt a standard 60 or 90-pound jackhammer on the pavement could have triggered this (unless the deterioration of the steel framing was incredibly severe). Compare that to the resonance from, say, several fully loaded semi-tankers or cement trucks bouncing across this thing at 70MPH day in and day out. But who knows at this point? If there were, indeed, "out-of-plane girders" all normal assumptions can be thrown out the proverbial window.

Yes, one would need to consider all the stresses the bridge has been under, but on "resonant destruction": Consider something like Tesla's oscillator. Or "soldiers marching in unison across a bridge." It's not the "brute force" that is doing the destruction when resonant frequencies destroy something. It is the build-up of wave energy -- the super-imposition of the compressions and rarefactions of the waves moving through a structure -- which fatigues the materials and causes the failure.

It would be a "freak" occurrence if the jack-hammer use did set up resonant frequencies in the structure, but something I wouldn't ignore as a possible factor this early in the investigation.

[red-beard]

Appearently, the bridge had a score of 50 out of 120 on it's rating. It was also described as being deficient. And for traffic, it was #12 for traffic over a bridge with a deficient rating. Makes me wonder where the other 11 are...

[techweenie]

This will be discussed endlessly, but didn't the legislature pass a transportation bill that included infrastructure repair in '05 that was vetoed by the governor?

Anyone catch Bush's seconds of 'condolences' before he went into a Dem-bashing whine-fest?

[mattdavis11]

Listen guys, I don't drop political crap in your useless post, keep it the hell out of mine. OK?

This is just awful. I hope for the best of the ones left trapped.

[MRM]

I agree. For at least a day or two can we as Pelicanites rise a bit above the average and have enough respect to not twist the tragedy into a political blame game? There will be time enough for that later and plenty to go around.

[berettafan]

Originally Posted by competentone

Yes, one would need to consider all the stresses the bridge has been under, but on "resonant destruction": Consider something like Tesla's oscillator. Or "soldiers marching in unison across a bridge." It's not the "brute force" that is doing the destruction when resonant frequencies destroy something. It is the build-up of wave energy -- the super-imposition of the compressions and rarefactions of the waves moving through a structure -- which fatigues the materials and causes the failure.

It would be a "freak" occurrence if the jack-hammer use did set up resonant frequencies in the structure, but something I wouldn't ignore as a possible factor this early in the investigation.

saw that on a Mythbusters. really interesting theory.

[berettafan]

History Channel (or was it Discovery?) recently ran an excellent show on the 'Bridges of New York City'. Amazing what bridges do.

[Tobra]

Sadly, this is a problem all over the country. We have neglected vital infrastructure for a very long time. We just have nicer weather here in Cali or the roads would be worse than this one that just collapsed.

What a world we live in that I can call video like that up at the click of a button right after it happens

[Chuck Moreland]

Watching that video, it strikes me that the first section failed in two places simultaneously. It falls straight down, not hinging down as would result from a single failure, or two failures spaced even a few seconds apart. How strange, and seemingly unlikely.

The second failure point is out of camera view.

Was that the first section that dropped, or is there another section that dropped first out of camera view?