Minneapolis Disaster

<div class='quotetop'>QUOTE(airportkid @ Aug 1 2007, 10:55 PM) [snapback]489056[/snapback]</div>

From what i saw from supposed experts on the news here, The bridge was appropriately designed to be able to withstand something like this. The explanation was that there was a single arch going over the river, along with two trusses on either side. The supports and pavements for them were seperated so that if one failed it wouldn't take the others with it. Very similar to those "ancient days" where one section shouldn't take out the entire bridge.

Witness reports say that the first section fell and the rest of the bridge twisted and snapped sort of like a rubber band. Not really sure what that means, but i would guess there were a number of structural cracks, and when the first section went it crashed into a support for the section next to it, which happened to have an existing crack which then broke, and it sort of domino'd in that fashion.

 

I was a bridge inspector for 9 years. It was a highly stressful job because it had impossible deadlines and workload, with a certain number of bridges that had to be inspected, with elaborate and lengthy reports to write, especially for old bridges with lots of defects and of course the job had huge responsibilities for protecting people's lives.

When I found defects in a bridge that required its closing, the big boss didn't applaud my efforts. He was mad at me for being a trouble maker.

I was always the bearer of bad news, with things that had to be repaired. I was not popular with management. (I'm still not, I'm an engineer, not a politician).

There was also danger involved, as I spent most of my time on ladders, in a bucket under a bridge and many feet above the ground, or playing in traffic looking at bridge decks.
Harry

 

<div class='quotetop'>QUOTE(Godiva @ Aug 2 2007, 01:28 AM) [snapback]489097[/snapback]</div>

Such an unfortunate disaster, my thoughts and prayers go out to the victims and their families.

Although not anywhere near the same scale, it reminds me of a similar story last September when an overpass near my hometown of Montreal collapsed, crushing 2 cars underneath killing 5 people. I remember hearing the 28-year-old woman was pregnant in her first trimester, though that story does not mention it.

I think the only saving grace in that disaster was that it happened around noon on a Saturday and not during rush hour, as highway that it crosses is a route for many commuters.

Of course, this overpass was solid concrete and 36 years old, similar age to the Minneapolis bridge and hundreds of other overpasses across Quebec and many other states and/or provinces. Furthermore, the overpass had just been inspected a few months earlier (IIRC) and given a clean bill of health. Last I heard, 'experts' were explaining the high use of salt on Quebec winter highways creates a corrosive mist that eats away at the steel components of these bridges/overpasses. Yikes.

Stories like this sure do a great job of making people's paranoid... :mellow:

 

Another Minnesotan checking in here. I don't know anyone affected directly ...yet.

This is a huge blow to our infrastructure in MN.
That bridge was the most heavily used in the state and it's going to massive affect people's ability to get around. If the twin cities were simese twins, they just got seperated.
Early word here this morning is the commutes aren't too bad today, since many people are staying home. But as people start going back to work, the detour routes are going to struggle to keep up for the next 3 years.

 

Pictures show at least one of the piers tipped. A pier should never tip, even when a bridge falls. The tilted pier indicates serious problems with that pier, which may have caused the collapse.

The collapse of a Thruway bridge in New York was caused by undermining of a pier, which gave way in a flood situation. That pier was not on pilings, and was not adequately protected from scour.

It will take some time before the cause is determined, but that tilted pier is a clue, and a possible cause.

Problems with a bridge pier are difficult to spot. It might have been on piles that deteriorated.

Harry

 

We almost added our black prius to that bridge. my wife and I drove to northern suburbs last night at 5:30 to watch a softball tournament. we almost took I35, but decided to take another route that is a bit closer and which had less traffic showing on the MNDOT website. Had we taken 35, we probably would have crossed over that bridge about 10 min. before it tumbled.

didn't find out about it until tourney was cancelled by lightning and we went nearby for a bite. then had to tell a number of people we had to stay off cell phones when they got through to check on us (only phones we have). our sympathy goes out to those affected. yikes.

rpm

 

this disaster and the reports two years ago deeming the bridge to have major structural faults does hit home hard here.

1) being in the Puget Sound region with its many bridges

2) having gone thru a major earthquake 6 years ago

3) already identified structural issues with several bridges in the area and our legendary inability to fund any type of major publics work projects (we have a few bridges that have been recommended for replacement for decades now)

as far as public works projects, i have never lived in area that is as tight, short-sighted and unprepared for growth in my life.

the list gets bigger and bigger every day. now to have abandoned a multi billion dollar nuclear power generation system is something that several places have done, but i doubt that they blew as much money as we did in the process.

the Alaskan Way Viaduct, the Commuter Rail, other major traffic flow issues too numerous to mention, even something that defines the signature of Seattle like the Monorail cannot find funding in an area that has a HUGE amount of available capital...pretty sad and the list goes on and on.

i hope we dont come to something like Minnesota first before something gets done here

 

I am okay too. I live only a mile away (the opposite side of downtown) and go to grad school at the University of Minnesota so I am intimately familiar with this bridge. Yesterday, a little before 6, I was about to head that way to get some Pet supplies at a Petsmart, but Mom called (what she only does once a month) to see how I was doing. After getting off of the phone, Wife was flipping channels and skipped over the news channels (as usual), I saw a glimpse of panic in the news room, told her turn the channel back and there it was. If it wasn't for mom, I might have been there just in time. I am sure a lot of us think that if we did things just a bit differently, we could have been there too.

As a trained Civil engineer (doing environmental now), it is hard to imagine that this happens since there is so much that goes into building and inspecting structures, and half of the road was closed to traffic at the time so the bridge was far from a maximum load. But at the same time, the vast unfunding of infrastructure across the country makes me think that has been bound to happen, and will probably happen again unless there is a massive investment into replacing aging bridge structures (which I am skeptical of happening). Push your federal and state legislatures to take bridges seriously. The interstates were built 30-50 years ago and there is a lot of bridges becoming old and compromised.

 

This was obviously the topic of discussion over morning coffee at work today, one of my co-workers wife had quite the hair raising experience over this. She works at HCMC and got off work at about 5:30 or so, and usually takes used the 35W bridge. After she got to her car and started driving she saw the traffic jam due to the lane restrictions sh she took an alternate and crossed on the bridge thatt's in all the photos of the scene. As she was crossing the river, she heard the noise and looked over to see the whole collapse of the 35W bridge. She didn't get much sleep last night...

 

I saw a news picture of the Silver Prius on the bridge. It's hanging onto the edge, but apparently intact. Marked by recovery personnel with "17A" on the windshield.

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<div class='quotetop'>QUOTE(eagle33199 @ Aug 2 2007, 06:25 AM) [snapback]489156[/snapback]</div>

I don't think that's true of this structure. This is a steel truss deck. As I understand, engineers refer to these as "houses of cards." There is no fail-safe load path; when one major structural support goes, the entire thing falls.

This design is an artifact of the '50's, actually. By the 70's, they'd fallen out of favor in favor of more robust structures.

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One other observation: it's amazing how we defer maintenance on our infrastructure...then, when it fails, there's suddenly "an emergency" that's "not about money, it's about public safety."

Now there will probably be a commission to discuss the issue and appropriate funds dedicated to "fix America's failing infrastructure."

(Hello, Bechtel? it's your patron --I mean, the Government-- calling...)

Soon this will become a top national priority...that means we'll rush the project, end up paying too much, and likely receive a significant quantity of substandard work.

 

Like i said, supposed expert on the news... i took it with a grain of salt, given the quality of commentary i've come to expect from news sources Felt it was still important enough to pass on what was being said though... even if it was later proven wrong.

 

<div class='quotetop'>QUOTE(PriusGirlNJ @ Aug 6 2007, 10:54 AM) [snapback]491260[/snapback]</div>

They're re-ordering them. Looks like slides 23 and 28 now.
http://wcco.com/slideshows/local_slideshow...4/view?slide=23

Apparently it's more stable than it looks, since one worker is seen leaning against it as he talks.

You also gotta wonder what was going thru the mind of the Honda driver in slide 8, feet from relative safety, but still managed to stay upright, just barely.

 

Don't know if you all have heard this yet, but on the news last night i heard MINDOT is taking bids for a "Design Build" contract on the new bridge - Basically it means they'll start building before they've completed the design, and just sort of designing as they go along. Does this seem like a recipe for disaster to anyone else?

 

They can take existing structural designs and start building the base, while they design the actual look of the bridge. I'm not worried about it. Anything built today will be a much better design and build then nearly any 40 year old bridge. Time is of the essence here. That bridge is too important to squabble over the look of it for months before starting the foundation and framing work that would probably be the same either way.

It'd be nice if it could handle light rail!

 

The media has taken this story and started checking into our states bridge systems. What they found was not good, most of our bridges are in need of replacment. They even showed one small bridge litterally crumbling underneath....

 

With it coming up on 1 year since the 35W bridge fell, the local news has been doing some coverage on the event. On one station over the weekend, they talked to the owner of the silver Prius that was on one section of the bridge. She described her experience during the colapse, she was uninjuried and she said that in fact she thought she could drive her car away, but when she got out, found out the rear wheels were in fact hanging off the broken section. Never mentioned though what ever happened to her Prius.
By the way, the new bridge may be ready to open some time in September.