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The Science of Bridge Collapse Prevention
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.'"
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
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.
I have a method of Minnesota infrastructure maintenance that can assure sound bridges. My technique involves billing the Twins owner for the $392 million of government revenue (collected via a sale tax hike) being used to fund the new $522 million baseball stadium. My technique also involves continuing to dash the hopes of Minnesota football fans for a new government funded $0.5 billion football stadium. Instead, let the team owners rely on sports geek revenue to fund their stadiums, and misappropriate the tax revenue into infrastructure.
On the other hand, perhaps it isn't necessary to piss off all the Minnesota sports geeks (read: voters) and instead utilize the $2 billion dollar state surplus to deal with the states bridges. But alas, there are voters to buy with that money.
This is about the priorities of the citizens of a staggeringly wealthy nation being focused on everything but the infrastructure.
Lurking at the bottom of the gravity well, getting old
I had the opportunity to take a course on U.S. Intelligence and National Security from a gentleman who had worked on the Senate Intelligence Committee as a staffer for 10 years during the Cold War, specifically during the Carter and Reagan administrations.
Discussing the politics of funding, he pointed out that it was easy - very, very easy - to get funding for new photo and signals intelligence sattelites, listening equipment, spy planes, and toys. He noted that, yes, some lobbying went on for these projects, but the lobbying isn't what swayed Congress - it was the new and shiny. They could all go home and say to themselves "wow, I put up a massive spy sattelite that can photograph buttons on Russian officers!"
However, when it came to support for this equipment - analysts to look at the data they gathered, technicians to keep them running, maintenance facilities, etc. - they always came up short. In some instances, multi-million dollar pieces of equipment were purchased and deployed only to have the data they gathered analyzed only long after it was too old to be useful, assuming it was ever analyzed at all.
I realize that this post is a bit off topic, but the problem of not supporting what is already there exists all through government. In the case of this bridge, shutting it down would have met with massive protest from all involved. Projects would have caused inconvenience, just as increased personnel staffing creates great cost for the government in many areas. People do the same thing all the time - buy new cars and toys, but never spend the money on maintenance, it all went to the toy. But if we build it or buy it we better be able to keep it in good shape.