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.'"

Comments

Re:Barriers/Lights

[choongiri]

Meanwhile, engineering research projects, including one at the University of Missouri-Columbia, were already under way long before this week's bridge collapse to advance the science of bridge monitoring. At the school, work is being done on a large-scale sensor system that would be fastened to several concrete bridge piers below a span to alert officials about even the slightest tilting or swaying of critical piers supporting a bridge.

Re:Some of the locals seemed to know...

[Paktu]

There's conflicting reports about it. The Feds inspected it a few years ago and said it was in immediate need of repair, but the state sent in people who claimed it would be viable until 2020. While it might appear that the state just didn't want to spend money, keep in mind that Minnesota has the third lowest percentage of structurally deficient bridges, so it's not like there were other major priorities that were sucking up funding.

Re:The bigger problem

[Anonymous Coward]

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.

Re:Some of the locals seemed to know...

[Thorrablot]

Yes - there's a good writeup here already.

The bridge is a truss arch bridge built in 1967. The design doesn't interfere with river traffic (well, up until two days ago anyways) - but I did hear an interview with a Berkeley professor describe how such bridges are no longer built due to their lack of redundancy in case of span failure.

Re:Some of the locals seemed to know...

[moosesocks]

Likewise, you're not exactly going to be able to attract funding to fix or replace the bridge if you're going around telling everybody that everything's just peachy.

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.