O.T. BRIDGE COLLAPSE

[Anonymous]

Just after 6:00PM tonight, the 1900-foot-long Highway 35W bridge across the Mississippi River in Minneapolis collapsed. The cause is unkown. 

Sorry FM.  I was hoping not to duplicate the news, but we posted at the same time.  I am near Minneapolis, and watching all the news.  It should be interesting to find out what caused it.  There are 50 cars in the river.

[Limitedclear]

Just after 6:00PM tonight, the 1900-foot-long Highway 35W bridge across the Mississippi River in Minneapolis collapsed. The cause is unkown. 

Sorry FM.  I was hoping not to duplicate the news, but we posted at the same time.  I am near Minneapolis, and watching all the news.  It should be interesting to find out what caused it.  There are 50 cars in the river.

Ouch.

LC

[tcwright973]

I noticed on CNN that there appears to be some covered hoppers and tank cars involved as well. My map program says that they are on a BNSF line.

Tom

[Anonymous]

That bridge had an unsupported clear span of over 400 feet at the center.  I think it was a kind of box truss structure below the main deck.  I would think that whatever failed was fairly localized, and then that failure and localized collapse introduced a variety of tension and compression forces that spread thoughout the structure and brought down the entire 1900-foot bridge kind of like falling dominos.

 I just saw a guy being interviewed who said he has been in the bridge business for over 30 years, and has never seen anything like this.  Policticians are begining to seize the opportunity to blame it on the public's unwillingness to accept tax increases to pay for infrastructure upgrades.  They would have us believe that when funding is inadequate, they just don't inspect the bridges.  I wonder if officials who make statements like that are thinking through what they are saying.  If there is not adequate funding to inspect the bridge, failure to close it should be a crime.

Nobody wants to speculate on terroism or sabotage for any other motive.  They assure us that they have no evidence of that.  However, if there is such evidence, it is probably submerged in the river, under the bridge.  Some witnesses reported hearing an explosion at the onset of the collapse.  Considering all the possible causes, sabotage is about the only one that is feasible in this incident.    

[tomikawaTT]

Bit of a rush to judgement, there, Bucyrus!

Having been present at several accident investigations, I have heard everything from breaking wood beams to lightning described as, "Sounded like an explosion."  OTOH, the one REAL explosion (a BLEVE) was described as, "a loud Whoom!"  Any lawyer or investigator will tell you that so-called 'eyewitnesses' are probably the least reliable sources of information about a civil or mechanical engineering failure.

So, what do I think caused the collapse?  Considering the total lack of engineering data in the media coverage, I refuse to try to form an opinion.  Come back when the failure analysis people release their report and I might give you one - based on study and investigation, not ignorance.

My sincerest sympathy goes out to the spirits of those who died, and the families and friends they left behind.  As for the agenda-pushing politicians who jumped on this tragedy as a podium from which to expound their 'wisdom'...   HEY!  POPPA-ZIT!  MORE DIRTY DIAPERS!!!

Chuck (former USAF Quality Control inspector)

[Poppa_Zit]

 As for the agenda-pushing politicians who jumped on this tragedy as a podium from which to expound their 'wisdom'...   HEY!  POPPA-ZIT!  MORE DIRTY DIAPERS!!!

Chuck (former USAF Quality Control inspector)

You ain't kidding, Chuck. Instead of the politicans blaming the taxpayers for not sanctioning tax increases to pay for infrastructure inspections and repairs, maybe we just need new politicians.

Or, they'll assign the blame to beaureaucrats.

But whatever, it won't be their fault. A politican's 4 main jobs:

1. Get reelected

2. Get reelected

3. Raise plenty of money to get reelected

4. Learn how to convincingly delegate blame so you can get reelected

For the sake of those most affected by this tragedy, let us hope politicians stay away from the site. The people of Minnesota do not need to have the fallen bridge used as a photo op or background for soapbox statements.

May God bless everyone who responded to this emergency.  

[Anonymous]

Bit of a rush to judgement, there, Bucyrus!

Having been present at several accident investigations, I have heard everything from breaking wood beams to lightning described as, "Sounded like an explosion."  OTOH, the one REAL explosion (a BLEVE) was described as, "a loud Whoom!"  Any lawyer or investigator will tell you that so-called 'eyewitnesses' are probably the least reliable sources of information about a civil or mechanical engineering failure.

So, what do I think caused the collapse?  Considering the total lack of engineering data in the media coverage, I refuse to try to form an opinion.  Come back when the failure analysis people release their report and I might give you one - based on study and investigation, not ignorance.

My sincerest sympathy goes out to the spirits of those who died, and the families and friends they left behind.  As for the agenda-pushing politicians who jumped on this tragedy as a podium from which to expound their 'wisdom'...   HEY!  POPPA-ZIT!  MORE DIRTY DIAPERS!!!

Chuck (former USAF Quality Control inspector)

I made no judgement about it, but I am free to speculate. 

[sanvtoman]

 One of the news people was calling the covered hopper under the bridge a passenger car!

[JSGreen]

are they putting shackles in covered hoppers now?

[DMUinCT]

Watch this one. A standard Bridge Design on the Interstate Highway System.

[CANADIANPACIFIC2816]

are they putting shackles in covered hoppers now?

A lot of our news media people and politicians belong in  freight cars equipped with shackles.

CANADIANPACIFIC2816

[jeaton]

Anyone interested in some facts about the state of US highways and bridges?

http://www.msnbc.msn.com/id/20095291/

[solzrules]

I could venture some speculation -

They were resurfacing the bridge, a process in which they usually chip off a few inches of concrete or asphalt in order to repave it.  This requires jackhammers, and if they are anything like Milwaukee they probably have 20 guys out there pounding away.  If there were any small structural cracks or weaknesses this could have been a potential weak spot when you have two full lanes of traffic and guys going to town with the air hammers.  It also seems from the video that the bridge failed at one point at one end.  It could be that when one section let go the weight of that one section coming down brought the rest of the bridge with it. 

Just speculation, mind you, not based on any firsthand knowledge.

[tree68]

News reports this morning indicate that the condition of the bridge was recognized as early as 1990.

I was thinking about the video that shows the bridge collapsing - it appears that at first, at least, everything dropped pretty much straight down.  That says to me that it was probably a central structural member that failed.  Imagine the result if the failure had occured on one side, causing the entire structure to roll as it fell...

[JSGreen]

Discovery Channel did a show last night on "Why Bridges Collapse".  It started with some news footage of the I35 collapse, then went to other bridge collapses to examine why they happened...

I remembered some of them from the News, but there were a lot more than I would have imagined.  Didnt even address the Tacoma narrows bridge...had lots of others to choose from...they were all interstate bridges too, I believe.  

Glad I am not beginning a long freeway drive that goes over lots of bridges today... 

[Anonymous]

Looking at the video and most recent computer animations, it appears as though the entire free span truss (over 500 ft. long) fell straight down, with the west end a little ahead of the east end in the fall.  That suggests that the failure occurred at the west end of the free span truss, very near the west support pier.  The drop began there, and then the east end broke free as the deck tilted from the west end break. 

They keep mentioning how the expansion slides were frozen by corosion over time.  I wonder if those are rollers or just friction slides.  If they are rollers, I could see how the rollers could be frozen so they could not turn.  Presumeably, the frozen rollers would still slide to accommodate the expansion and contraction of the span.  But if the bearings are just sliding pads, and if those are frozen, I don't understand how the structure could survive if it were frozen against expansion and contraction.

[Heartland Division CB&Q]

I have questions for the experts who amy beout there. Truck sizes have trended larger over the decades. I believe when I 35 W Bridge was designed, maximum truck trailers were 40'.  is that correct, experts?  Congress since the allowed 45' trailers, and then 48' trailers.  Finally, we have 53' trailers with widths expanded to 110".

Could we be facing a big problem as a result of expanded truck capacities?  Could the larger truck capacities contribute a role in the I 35 W bridge collapse?

Can that be the case with all highway bridges designed when trucks were smaller?
I'm no expert, but I wonder.  I also wonder about railroad bridges spanning large rivers.  Some are 100 years old and trains are certainly larger.

Any civil engineers out there who can answer?  Thanks. 

 

[squeeze]

Having seen demolition of bridges being performed, and after watching the clips of this bridge coming down, there was similarity in the amount of time that the bridge fell and how it fell. I make no speculation, just an observation. Most of the the spans that are brought down with explosives are ancient and not practical to repair/rebuild. This bridge was only 40 something and should have been in relatively decent shape. I'm not a structural engineer and make no claims, but it seems as though this collapse did not look/act like just one end gave way. My observation only. My prayers are with all those involved. I live in the Pgh area and realize that being the land of bridges here, we may be in a world of hurt.