The Science of Bridge Collapse Prevention 276
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.'"
Wireless Sensor Networks (Score:2, Interesting)
Some of the locals seemed to know... (Score:5, Interesting)
This smacks of criminal negligence - complete catastrophic failure in 4 seconds could not have been an undetectable condition.
Re:How about just using existing know-how... (Score:5, Interesting)
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.
How about building bridges like the romans (Score:1, Interesting)
Little maintenance.
No sensors.
No inspections.
No reports.
My technique (Score:5, Interesting)
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 [publicradio.org] to deal with the states bridges. But alas, there are voters to buy [ncsl.org] with that money.
This is about the priorities of the citizens of a staggeringly wealthy nation being focused on everything but the infrastructure.
Re:Wireless Sensor Networks (Score:1, Interesting)
See http://abcnews.go.com/Technology/story?id=3441742 [go.com]
"The idea is to put arrays of sensors on structures, such as bridges, and look for the changes of patterns of signals coming out of those sensors that would give an indication of damage forming and if it is propagating," said Chuck Farrar, a civil engineer at the lab.
Re:Bridge collapse prevention "someday" (Score:3, Interesting)
I used to work for the state highway authority, working on traffic signals. When I was there the entire bridge department were made redundant and replaced by contractors. No matter how much you document these things, you still need continuity from one generation to the next. The old guys have to be around to tell the young guys to look out for this and that, or it may cause problems.
But it is cheaper to outsource.
Re:ironic (Score:3, Interesting)
Until someone miscalculates.
Re:How about just using existing know-how... (Score:3, Interesting)
Something similar may have happened with the I-35W bridge, a lack of redundancy led to the bridge to collapse as a result of a single piece failing.
By the way, most aircraft are required to maintain structural integrity after the failure of a single structural element such as a wing spar.
Re:Some of the locals seemed to know... (Score:3, Interesting)
Ahh, here we go. It's the GOPs fault. If only we'd spent federal money used for the Iraq war to fix this bridge. This was the first comment on Kos about this tragedy and it was echoed verbatim by several reporters in the mainstream media. I don't mean they just had the same thought, I mean they used the same damn words.
Then there's the other one.. if only they'd instituted a 5 cent/gallon gas tax that was proposed. That's a more simple "pay as you go" (e.g. tax and spend) approach instead of the "creative approach" those damn Republicans in the state were trying to come up with to finance road work. That was courtesy of the Minneapolis Star.
Fact is that Minnesota (like most states) has a budget surplus and could have paid for the bridge repair without raising taxes. Perhaps they'd have had to spend less on that new stadium or less on that new art gallery. So what? Can we maybe all agree that fixing the roads ought to be higher on the priority list than doling out money for a privately owned stadium?
All I can figure is that several people probably decided that it was unlikely that the bridge was going to collapse. They had conflicting reports from engineers, some saying it would in say 5-10 years, others giving it more like 20 so long as some repairs were done. So what did they do? They paid for the repairs figuring that repairing the existing structure to get a few more years out of it was a responsible choice vs. building an entirely new bridge.
It's disingenuous to suggest as others have that they paid off the state inspector to paint a more rosy picture after the federal inspector gave a pretty bleak one. It was in nobody's interest to get a more rosy picture since the state still had to pay for the repairs which ultimately, with the benefit of hindsight, were shown not to work.
In the end, I think what we're going to see here is that it wasn't really a case of wanton disregard for safety but rather a reasonable and responsible choice (a calculated risk) that happened to go horribly wrong. It's easy to say now that they should have paid for a new bridge rather than paid to repair the existing one, but that's only now with hindsight.
The good news is that the people of Minnesota really banded together and helped each other out of the tragedy. One of the boys on the school bus apparently took it upon himself to open the door and lead the people out. People on the ground stood by the bus on a crumbling bridge and helped the passengers out. Divers are working in absolutely insane conditions to find the dead so they can give the family a definite answer. That's the real story here. There is still some good in this world, even in the face of tragedy.
Reminds me of a lecture I once heard... (Score:5, Interesting)
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.
Re:The bigger problem (Score:3, Interesting)
The media likes the hype of saying 'it was under repair at the time'.
Re:Some of the locals seemed to know... (Score:3, Interesting)
Personally, I sort of doubt that this could have been prevented. It's one of those one-in-a-billion sort of odds that unfortunately caught up with us...
I'm more than a bit irked at the media for taking the "structurally deficient" term, and plastering it all over the news without a very clear understanding of what it means. There's no cause for a panic or a rucus -- our bridges are no more dangerous today than they were last week. Hell, we don't even know what caused the bridge to collapse, and ordering all sorts of emergency inspections (which has been done in many many states so far) is pointless considering that the bridge that collapsed was previously deemed to be safe on multiple occasions.
Of course, other recent incidents such as the con edison steam explosion in NYC reek of criminal negligence.
Dying by being hit by a meteorite is a uncontrollable event which is completely blameless. Dying because a bridge gave out is an act you can lay blame for. The engineers who checked the bridge didn't do their job. A freak accident would be if a whale and a bowl of petunia's sudden;t landed on the bridge and caused it's collapse. Buckling and giving out on it's own is negligence by the state due to lack of proper engineering.
Playing with lives... (Score:2, Interesting)