Picture of I-35W prior to collapse (to get an idea what it looked like)

[Poll_Blind]

PB

[Junkdrawer]

1. Note the rust at the critical jucntures...Vibrations from the pile drivers...

combined with the rush hour loads...
:shrug:

[Eric J in MN]

9. Good point. Look at how rusted it was above the concrete block nearest

...the viewer.

[Junkdrawer]

17. Sandblast it, paint it, and it's good as new...right????

...Well, that's all we can afford....

[Junkdrawer]

22. A blowup of that part of the image...

[JuniperLea]

57. That's a pretty freaking tiny point of contact...

Between the steel and the pylon!

[Xithras]

59. Yeah, I'm thinking the main span was pushed off.

The witnesses claim that it was actually one of the approach ramps that collapsed first. If the collapsing approach ramp pushed on the bridge (as it probably would have) it wouldn't have taken much to shear those tiny contact points and push the bridge off the piers. A horizontal push of as little as 12" may have been all it took to bring it down. Just enough to knock it off its foundation.

[MrMickeysMom]

46. As a person living in Pittsburgh, this makes me nervous...

... Anyone who's here will note the age of "the city of bridges" and the poor infrastructure" of this commonwealth/state. Talk about rust at your critical junctures... sheesh...

I hope this excellerates the wake up call. It's unacceptable.

[Junkdrawer]

49. Homestead High Level Bridge...n/t

[MrMickeysMom]

50. Matter of fact, THAT one is under repair as we speak! eom

[Junkdrawer]

51. I know. That's where I shop for groceries.

BEFORE this happened, I shuddered every time I crossed the thing.

[Junkdrawer]

53. Note the similar structure...only much, much higher....

http://en.wikipedia.org/wiki/Homestead_Grays_Bridge

[MrMickeysMom]

54. Interesting... only one way to pay for all this federal spending, Chimp just said

In response to what happened and in response to all the other bridges, I believe he's covering his ass about how we don't have this in the budget.

What insanity. Anyway, nice to see you're local, and good traveling to you!

[JuniperLea]

58. We can borrow money to kill people...

And put our nation in debt up to our great-grand-children's eyeballs, but we have no money in the budget to keep our citizens safe.

That subhuman appointed to presidency needs to go!

[Deja Q]

2. Not the most recent; the bridge has been undergoing construction for a couple months now.

:(

[Poll_Blind]

4. If you can find pics showing construction, please post 'em. I'd be...

...curious to get a better idea of what it looked like today.

PB

[ayeshahaqqiqa]

3. Thanks for this

I was wondering how difficult it would be for rescue people to reach them. I recall when the I-40 bridge collapsed over the Arkansas River-it's really in the middle of nowhere. Glad to see there are roadways, etc, nearby to help with rescue efforts. My heart and prayers are with my brothers and sisters in the Twin Cities.

[karlrschneider]

6. One of my friends missed falling into the river in that incident by about 30 seconds.

He saw cars disappearing in front of him and couldn't figure out what was happening. Stopped just in time.
:scared:

[snacker]

16. Oh my god...how terrifying for him.

So glad to hear he's safe. Sending lots of prayers to everyone in Minneapolis/St. Paul tonight. Many people will be touched by this tragedy.

[karlrschneider]

20. Indeed, I concur with that. The one here was hit by a barge, though, so it was

easily explained. I think it will be a while before we know what happened in Minneapolis. Oh, here's a bit of info on the one I mentioned
http://www.odl.state.ok.us/usinfo/topiclists/us-i40.htM

[Poll_Blind]

7. Apparently at least one hospital is extremely close, thankfully. n/t

PB

[zulchzulu]

5. Live radio report from Minneapolis stream

http://www.wccoradio.com/

Click on Listen Live

[Poll_Blind]

28. Thanks! n/t

PB

[MADem]

8. Olbermann on MSNBC just said it had been inspected in the last three years.

Heckuvajob, Brownie, or what????

He's going through a litany of the many ways a bridge can fail...

[Eric J in MN]

12. Do you mean "hasn't been inspected" or

...are you saying a recent inspection was poorly done?

[MADem]

26. A recent inspection WAS done. It could be that something happened to

that bridge AFTER the inspection to cause the weakening...or, it could be that it was poorly done.

[Eric J in MN]

27. I just found this on inspections.

http://www.twincities.com/allheadlines/ci_6518669?source=rv&nclick_check=1

=====
The bridge, built in 1967, had both north and southbound lanes inspected by the Minnesota Department of Transportation in 2004, according to KSTP-TV.
======

[lonestarnot]

31. So 3 years ago, it looked like it wouldn't crap out. Why do we wait 3 years to inspect?

[lonestarnot]

32. Guess we have traffic, double posting.

[Lithos]

47. That has been amended

They say it was inspected in both 2005 and 2006.

My personal guess is that it failed due to fatigue, age, uneven loading (possibly torsional loading on the arch) caused by having several lanes shut down and bumper to bumper traffic on the open lanes, coupled with vibrational stress caused by the cars and the construction. There may have even been an inherent flaw during initial construction too or possibly damage caused by the repairs.

L-

[Maddy McCall]

15. When I worked for the MS DOT, we did yearly bridge inspections.

3 years is too long to go without a bridge inspection, especially if there's barge/tug traffic underneath.

We used to do bridge inspections every year, sometimes more frequently if need arose, on the Mississippi River bridges when I worked for the DOT years ago.

[dflprincess]

21. Olbermann mentioned a bridge collapse in Scotland that was

caused by the bridge having to handle more traffic (apparently in that case rail traffic) than it was designed for. Apparently just the additional vibrations from more traffic can weaken the structure. This bridge is 40 years old and the way the Mpls/St Paul area has grown in the last couple decades and the subsequent traffic problems we now have, I have to wonder if this bridge was handling more traffic than it was designed for.

[achtung_circus]

30. He means the Tay Bridge, poor design.

http://en.wikipedia.org/wiki/Tay_Rail_Bridge

Investigators quickly determined that the cylindrical cast iron columns supporting the 13 longest spans of the bridge, each 245 ft (75 m) long, were of poor quality. In particular, the lugs used to attach the wrought iron bracing bars were moulded with the columns, introducing a fatal weakness. It was these lugs that failed first in the accident, and so destabilised the entire centre part of the bridge. No allowance for wind load had been made by Bouch; such calculations were not common practice until precipitated by the disaster. The High Girders section in the middle of the bridge was top heavy, making this part insecure. It was this section that collapsed.

[Maddy McCall]

10. Road surface is 64 feet above water.

[Harper_is_Bush]

11. I've never seen a bridge like that. It looks poorly designed, to this layman. n/t

[Poll_Blind]

14. Yeah, the connectors to the pylons look tiny, tiny. n/t

PB

[HysteryDiagnosis]

23. Exactly, it looks.... "underdone" imho as well, n/t

[karlrschneider]

25. It looks that way to me too, and I'm an engineer.

Too many of the structural members are in compression, not enough in tension. There is no 'fail-safe' principle applied to it...breakage of any piece that I can see will result in transferring substantial added loads to the adjacent ones.

[Junkdrawer]

29. Check this image...

The bridge was a unique design that avoided in-river pilings. Thus the show stress point was critical and had no fail-safe...and was corroded as hell....

[karlrschneider]

34. That looks like a pivoting expansion support which is fairly normal

I can't get a good perspective from that picture so can't tell how big that concrete piling actually is...I'd suppose around 5 or 6 feet in diameter. I kind of doubt, even with the corrosion, that particular point would be especially vulnerable (unless it was somehow damaged)...but the overall structure is pretty much a textbook of bad truss design.
I'm surprised it was built like that to begin with...

[Junkdrawer]

38. Everything you ever wanted to know about the bridge....

http://www.lrrb.org/pdf/200110.pdf

[karlrschneider]

42. Thanks but I think I'll pass on that 12 mb pdf for now

I'm stuck with dialup, our dsl is broken. Again. :mad:

[Junkdrawer]

52. Here's page 29 of the report (37 of the PDF)...

[karlrschneider]

55. Okay thanks. That's interesting but not necessarily a smoking gun, IMO

Stop drilling cracks is pretty standard practice but you wouldn't want to do it a whole bunch of places in the same vicinity. I probably shouldn't mention this but most airplanes have this kind of fix in many places. ;-)
The term 'diaphragm' is a bit odd to me, I presume it's what I'd normally call a 'gusset'...but I'm an aero engineer, not an ironworker. Not sure I love using undersize bolts though but I see the reasoning however I have to wonder about
shock loading on them. When my DSL comes back on I'll grab the file and look it over...
ks

[Junkdrawer]

56. I read it as what we Joe Homeowner repairmen call a Mending Plate...

Have you seen the video? Looks to me like the bridge gave way just inside the support columns...

http://www.kare11.com/video/player.aspx?aid=51385&bw=

[goodgd_yall]

60. One of the recommendations in the report

Part of the floor truss is supposed to be inspected every 6 months. I wonder if that was done.

[Neshanic]

48. I am not qualified, but that bridge looks like too much top, and not enough support...

it just looks to my laymans eyes that it's alot of bridge supported on only four points. It just looks "not right" to me. I don't think I have ever seen a bridge like that where it gives me that feeling. Especially in a climate like that.

[Cooley Hurd]

13. Windows Live Local images link:

http://local.live.com/default.aspx?v=2&cp=rgwtkq76wn78&style=o&lvl=1&tilt=-90&dir=0&alt=-1000&scene=6176719&encType=1

[Rick Myers]

18. WCCO reporting first fataility.

[partylessinOhio]

19. For years we have ignored infrastructure. How many more bridges

are near collapse but we must keep spending on credit into the future for war/invasion/killing?

This bridge looks poorly designed with too small steel girders. Not much to hold it up so it pancaked.

[gulfcoastliberal]

24. Sadly I think you're right and incidents like this will happen more and more.

This country has been gutted.

[deutsey]

33. I'm here in Minneapolis on business...The disaster area is right outside my window

I'm at the Holiday Inn Metrodome and can see everything from my room.

It's awful. I went downstairs about 20 minutes ago and it's chaotic...emergency vehicles everywhere, snarled traffic. And people sitting and eating dinner and drinking beer at open air cafes. Surreal.

[Poll_Blind]

35. That's terrible but I'm glad you're OK! n/t

PB

[deutsey]

40. Thanks...there was a chance that we were going to go over that bridge today

[Poll_Blind]

41. .

:scared:

[Poll_Blind]

36. New pic of collapsed bridge taken from closer angle to original pic

Updated the original message with it as well to get a better idea.

PB

[bigwillq]

37. Thanks for posting that pic

I've never seen a pic of this bridge pre-collapse

[Poll_Blind]

39. 64 feet above the water! When I was looking at the collapse images...

...I had no idea how high up it really was. What a nightmare.

PB

[razors edge]

43. Center span arch is too flat.

And too thin.

[MagickMuffin]

44. That's the way I see things as well

the other bridge seems to have more support in the middle of the river, whereas the one that collapsed didn't have any center support.

Unbelievable....

[razors edge]

45. The arch beams

don't look to be rolled to the radius, stress loads here are both axial and lateral, and the lateral ability looks weak for the total load.

[Left Is Write]

61. My husband drove that bridge twice a day every day for years until we moved out of state.

This whole thing is horrifying.

[bullwinkle428]

62. The Cedar Ave. Bridge (which sits next to it) looks SO MUCH MORE SOLID

in its design and construction! My brother and his family live in the Twin Cities, and I know I've passed over that bridge a number of times when we've gone into the east side of town or St. Paul to do things. I'm glad I never actually got a look at the underside of the bridge...perhaps the most surprising thing is that it held up nearly 40 years before there was an incident.