The question must be asked 16

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1. 

   Delay And Deny Posted 4:31 am
   07 Aug 2007

   "Climate Change" Dented My Fender
   Is "Climate Change" the new grassy knoll?
   
   John Bailo
   
   
   Supratext:

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2. 

   Matt G Posted 4:35 am
   07 Aug 2007

   InterestingAnd could be true only because you use the words "contribute to".  If the design was down to a difference of a degree or two, the bridge engineer was cutting things waaaaay too close (we use around a 15% safety factor in the heating and air conditioning industry - I would imagine bridge design is more like 50%+).  But even if s/he did cut things way too close, this wouldn't have mattered if there weren't extreme conditions.

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3. 

   sunflower Posted 5:33 am
   07 Aug 2007

   LoadedCombined loads of thermal cycling metal fatigue, heat of resurfacing, heat of the afternoon, dead load of grid lock, dead load of resurfacing materials and equipment, or some catastrophic failure like foundations, possibly Iran.  Its all speculation until we hear from the engineers.  I wish I had engineers.

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4. 

   hayden Posted 7:04 am
   07 Aug 2007

   Stupid> Did climate change contribute to the Minneapolis
   
   > bridge collapse?
   This is an absolutely stupid suggestion, and you people who are trying to blame every last pejorative happening on climate change are doing very serious damage to the cause.
   This bridge undergoes ~100 F in temperature swings every year. The thought that another 1-2 F is going to make any difference is really stupid, and just indicates your lack of scientific and engineering foundations.
   Shut up before you do any more damage to the real problem of getting the world to take climate change seriously.
   
    

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5. 

   Matt G Posted 7:12 am
   07 Aug 2007

   haydenNobody here is claiming to know what made the bridge collapse.  It's true this is speculation, but it's educated speculation.  1-2 F can make a huge difference in stress on a bridge, and it's fair to bring the cause of this 1-2 F as a factor.
   -Matt
   
    Mechanical Engineer

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6. 

   hayden Posted 7:31 am
   07 Aug 2007

   1-2 FMatt G, 1-2 F does not make a difference on a bridge that undergoes 100 F of variation a year, and which has withstood significantly larger tempertures than it did on the day of its collapse. There is no evidence whatsoever -- none -- that climate change contributed to the collapse of this bridge. If you have it, present it. If not, stop the pointless and useless speculation.

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7. 

   MarkUK Posted 7:45 am
   07 Aug 2007

   PleasePosts like this sometimes tempt me to move to the climate skeptics camp... Give me a break.

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8. 

   Matt G Posted 7:59 am
   07 Aug 2007

   1-2 degreesAssuming the expansion joints were touching.
   
   Assuming 12" thick concrete.
   
   Assuming 50' wide bridge.
   Thermal deformation:
   
   Dt = a*L*dT = 8E-6*478*2 = 0.092 inches
   
   F/A= a*Y*dT = 8E-6*4.5E6*2 = 72 psi
   
   A = 12*50*12 = 7200 in^2
   
   F = 3,732,480,000
   That's right.  3 trillion pounds of force would be acting on the bridge from these 1-2 degrees.  Of course, you'd never get there since the thing would likely fail before that.
   Again, bridges are designed such that the expansion joints never come close to closing.  And we don't know that they had.  My point is that 1-2 extra degrees F can certainly contribute to a bridge failing.

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9. 

   Matt G Posted 8:03 am
   07 Aug 2007

   correction(oops - that's 518,400 pounds of force.  still nothing to laugh at.)

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10. 

    queenofcali Posted 11:28 am
    07 Aug 2007

    Global warming causing Bridge CollapseActually, the Bridge was made out of recycled automobile tires and bicycle tires purchased at Walmart in Iran!  It was a little TOO stretchable and snapped BIGTIME!  It went from hot to cold, then cold to hot, then back again exactly ELEVENTEEN TIMES! 1,2,3,4,5,6,7,8,9,10,ELEVENTEEN!  Then it went BACKWARD, ELEVENTEEN, 10,9,8,7,6,5,4,3,2,1!  SNAP, CRACKLE AND A GREAT BIG POP!  Bridge could not withstand products from Iran!

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11. 

    Pangolin Posted 3:29 pm
    07 Aug 2007

    My WAG....That's Wild Ass Guess for the rest of you. I would speculate that a changed yearly cycle from several months of cold dry air being transformed into months of warm wet air.
    Warmth, water vapor and the prescence of salt is a recipe for steel corrosion. That could make the painting and inspection schedule that was designed for long cold winters defunct.
    Anybody who knows anything about the Golden Gate Bridge in San Francisco knows that painting and maintenance is an absolute OBSESSION of the bridge district.
    Neglect of a small factor of maintenance can lead to a major failure. I have seen more than a few houses flooded because the a plumber saved 75 cents on a part at some point. There are no trivial details in the maintenance of a structure. They are all important.
    Simply having warmer wetter winters could have defuncted what maintenance attempts were made.
    
    Put the Carbon Back

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12. 

    David Roberts Posted 4:36 pm
    07 Aug 2007

    EhLook, climate change is just an alteration in the atmosphere, so in some appropriately complex model of causality, it "contributes to" every bit of weather we experience. Weather, in turn, "contributes to" the behavior of virtually every outdoor object or structure.
    If I slip on a patch of ice, yes, in some tenuous way climate change "contributed." But it did not do so in any meaningful sense -- any number of more proximate causes provide a better explanation.
    So yeah, I guess it's technically right that climate change contributed to the bridge's collapse, but the only practical effect of saying so, as far as I can tell, is to provide those eager to mock environmentalists with ammunition.
    
    grist.org

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13. 

    spaceshaper Posted 9:44 pm
    07 Aug 2007

    The engineering climateOK, let's calm down here. I think what we have is an example of the old weather/climate confusion. While it may have been a very hot day in Minneapolis when the bridge collapsed it was certainly not outside the range of temperatures which the bridge's expansion joints SHOULD have been designed by normal engineering standards. Expansion joints need to accommodate the most extreme conditions a bridge is likely to encounter, not just average highs and lows. Structural engineering practice moreover is fairly conservative and would generally add a considerable margin of safety to the historical record. Temperatures of below -40° and over 100° have been recorded in the Minneapolis area, so the joints would have been designed to accommodate at least that range. They probably plugged in a number of something like 120° or more as a high: even engineers working for the gumint know that a bridge that stands only in "normal" conditions is unsatisfactory.
    That is not to say that the heat of that day was not a factor. Preliminary assessments have mentioned a possible "perfect storm" of conditions, including deferred maintenance, construction work, unusual loading conditions etc. That perfect storm may indeed have been combined with a design flaw, as was the case with the 1981 collapse of the Hyatt/Regency atrium bridge that killed over a hundred people. Some factors in which chronic heat and climate effects may have played a part include corrosion and creep or movement of the bridge sections over time from their original location which may have reduced the expansion capacity of a particular joint. I'm sure there are others. But "heat and climate effects" and "climate CHANGE effects" are not at all the same thing.
    That said, mention of climate change in connection with this failure may have some value as a heads-up to engineers, giving notice that they may need to widen the range of temperature parameters used in the design of new bridges and in the structural assessment of existing ones.
    
    The true meaning of life is to plant trees, under whose shade you do not expect to sit.

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14. 

    amazingdrx Posted 11:33 pm
    07 Aug 2007

    Infrastructure fatigueImagine the heat induced fatigue where temps rise to 120 now.  This is a new effect of GHG disaster.  150 on the roadway over bridges in the southwest?  
    But this is really due to oil war fatigue.  Tax dollars that ought to go to repairing US infrastructure are going to contractors like Halliburton to pretend to rebuild Iraq.
    The gutted, rotten results of multiple layers of subcontractors in Iraq with Cheney's company siphoning off most of the cash has left Iraq with no infrastructure and US with a collapsing infrastructure.
    And all those good jobs rebuilding america are gone.  Another Halliburton administration would find the same work crews that built that police academy in Iraq to rebuild our bridges.  3 dollar per day Bangladesh refugee crews?  Rebuilding bridges in Minnesota?
    Once halliburton owns our highways that is what will happen.  Give them another chance and watch it happen.  Privatize the highway system under a 911 hero Guliani administration!!  Hooray!!!
    
    http://amazngdrx.blogharbor.com/blog

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15. 

    CurtM Posted 1:05 pm
    08 Aug 2007

    Read the articles in the Star TribuneApparently severe maintenance issues have existed for over a decade and nothing has been done. It is not clear this bridge could be maintained -- I certainly don't recall it being painted. It was difficult enough to inspect! The weather here has significantly changed, however the swings are less (we don't get as cold in the winter) and though the summers are hotter overall the max temps haven't increased. Certainly last week was nothing special. The miracle of it all is that so few were killed. That is nothing short of astonishing.
    
        Curt in MN (for decades, with thousands of trips across the bridge)  

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16. 

    wiscidea Posted 3:57 am
    09 Aug 2007

    Republicans Are ResponsibleRepublicans have a long history of cutting taxes, neglecting infrastructure, and letting someone else pay for the results -- perhaps with their lives -- decades later.
    The bridge was probably constructed to barely withstand much more heating and cooling than is "normal" for the area. Just to save a buck. Republicans don't like to plan for once-a-decade problems... a winter requiring a little more salt, a summer a little warmer than usual... IDIOTS. How do they ever succeed in the business world?
    We need elected officials who want to plan and build as though our country will be around for a while, not like it is a business you can sell to some fool as soon as your buildings start to deteriorate and profits slip from lack of long-term investment!
    
    Forward!

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