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The Science of Bridge Collapse Prevention

Posted by Zonk on from the so-far-we-have-not-found-the-science dept.

toddatcw writes "In the wake of the Minneapolis Interstate 35W bridge collapse this week, Computerworld investigates ongoing research which could someday help to prevent future disasters. Acoustic emissions detection systems, which listen for the sounds of metal snapping on structures, are already sold and fitted. Likewise, a new generation of detector systems that monitor for tilting of bridge columns and piers are being designed, prototyped, and researched. 'Sound waves move more efficiently through solid objects than through air, making any sounds easier to listen out for, Tamutus said. "It's not amazing. It's simple. Doctors use stethoscopes all the time. If you put your ear on a train track, you can hear a train approaching from far away... The Sensor Highway II systems, which are portable and can be moved from bridge to bridge as needed, usually cost between $20,000 to several hundred thousand dollars each. Typically, evaluations take between one day and a week.'"

5 of 276 comments (clear)

  1. The bigger problem by weak* · · Score: 5, Insightful

    It was known well before the collapse that the bridge was in need of repairs. It seems that no public employee, elected or not, understands that prevention is better than reaction. New techniques to detect a heightened probability of failure are useful only if someone acts on the information once it is available.

    --
    The Schwartz space ain't from Spaceballs.
    1. Re:The bigger problem by Anonymous Coward · · Score: 5, Informative
      It was rated 'structurally deficient':

      The Minneapolis bridge's deck, or driving surface, was rated in "fair condition." The superstructure was in "poor condition," and the substructure in "satisfactory condition." It looks like the 'satisfactory' substructure is what failed. Repairs to the driving surface and the trivial superstructure were ongoing. There was no indication from inspections that the substructure was in need of immediate repairs.

      The classification of structurally deficient means that either the surface, the superstructure, or the substructure was rated poor. In this case it was the superstructure which for this particular bridge did not provide support. A little bit of repairs to the superstructure and this bridge would have been cleared of its structurally deficient rating.
    2. Re:The bigger problem by penix1 · · Score: 5, Insightful

      It seems that no public employee, elected or not, understands that prevention is better than reaction.


      No it isn't...

      This may seem callous and cold in the wake of this incident but in fact it is cheaper (hence "better") for the state to react sometimes than to mitigate a hazard. It is simple economics. The federal cost share is 75% federal, 25% state. In catastrophic events, that split drops to 90 / 10, or at the discretion of Congress, 100% federal (Katrina is 100% federal). If the hazard you are attempting to mitigate would cost more than if it fails, then it is cheaper to let it fail. Of course, you run the risk to life and property when you do this so it is a huge gamble.

      States are cash strapped with the thousands of "unfunded mandates" the federal government places on them. Everybody want services but don't want to pay for them in higher taxes. Then you get pandering politicians running on "lower taxes" campaigns further reducing a states ability to operate properly. It is a wonder it took this long for something to happen.
      --
      This is a sig. This is only a sig. Had this been an actual sig you would have been informed where to tune for more sigs.
  2. Some of the locals seemed to know... by Thorrablot · · Score: 5, Interesting

    I'm a Twin Cities resident (local name for Minneapolis/St. Paul), and have taken this bridge hundreds of times, as well as biked along trails on the riverbanks below it. It was never an attractive bridge, but certainly showed no obvious signs of problems. I was shocked to learn that a good friend of mine was told by a structural engineer two weeks ago that he "always avoids driving on that bridge during rush hour" - apparently the engineer had already read/heard something that we're just finding out.

    This smacks of criminal negligence - complete catastrophic failure in 4 seconds could not have been an undetectable condition.

    --
    Any sufficiently advanced technology is indistinguishable from a rigged demo. -- James Klass
  3. Re:How about just using existing know-how... by Paktu · · Score: 5, Interesting
    While it's easy to ask "why didn't they just make it redundant?", there are reasons behind these decisions. Please take a look at this link: http://www.visi.com/~jweeks/bridges/pages/ms16.htm l

    There's a lot of good info there, but here are the cliff notes:

    A University of Minnesota Civil Engineer in a report to MN-DOT recently noted that this bridge is considered to be a non-redundant structure. That is, if any one member fails, the entire bridge can collapse. A key factor is that there are only four pylons holding up the arch. Any damage to any one pylon would be catastrophic. The textbook example of a non-redundant bridge is the Silver Bridge over the Ohio River. It failed shortly before Christmas in 1967 resulting in 46 deaths. A single piece of hardware failed due to a tiny manufacturing defect. But that piece was non-redundant, and the entire bridge collapsed into the icy river. Today, bridge engineers design bridges so that any single piece of the bridge can fail without causing the entire bridge to collapse. It is tragic that the I-35W bridge was built a few years too early to benefit from that lesson.