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MEMS Sensors Secure Structures
7/19/2013

Sensors on the Morgan Street Bridge over Rock River, Rockford, Illinois, tracks strain on different parts of the structure during construction operations. (Source: HBM Engineering Group)
Sensors on the Morgan Street Bridge over Rock River, Rockford, Illinois, tracks strain on different parts of the structure during construction operations. (Source: HBM Engineering Group)

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elctrnx_lyf
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Re: Bridge safety
elctrnx_lyf   7/22/2013 4:50:46 AM
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As long as cost of developing this technology for the bridges is a very small portion of the actual bridge, it is definitely an added value. In the reverse I would defnitely not suggest to use such a technology. But overall this sounds really cool application of the technology.

wilber_xbox
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Re: Bridge safety
wilber_xbox   7/21/2013 1:03:38 PM
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True Peter, i think that it is a great example of how we can leverage today's techonology to save money and time. But i thought that sensors are used quite frequently to analyse the structural integrity. Isn't it very useful to use for example the piezo-material to know about the changes in the hotspots in a structure. Maybe the techniques used in the bridge are more sophisticated.

Peter Clarke
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Re: Bridge safety
Peter Clarke   7/20/2013 10:20:40 PM
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The advantage of MEMS with wireless reporting capability is that engineering visits the bridge once to install....and can then monitor the bridge on a "dashboard." This could save $$ on inspection visits as well as detecting changes in bridge integrity not readily spotted by the human eye that are indicators of needed repair or imminent failure.

Tom Murphy
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Re: Bridge safety
Tom Murphy   7/20/2013 9:41:22 PM
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That's a great example of what I mean, Susan, and exactly why it doesn't make it worthwhile to build a comprehensive network of sensors in all infrastructure.  The wester section of the Oakland Bay Bridge, to which you refer, was built in 1939 with supports resting on redwood columns driven into the mud beneath San Francisco Bay.  In 1989, a relatively small section fell during the World Series earthquake -- a serious incident that I believe resulted in injuries, but given the size of the bridge and the magnitude of the quake, a relatively small occurrence. 

It is arguable the Bay Bridge had been unsafe for many years because of those timbers and the way it was pieced together. And it has been increasingly unsafe each day since over the past 24 years. If there were sensors on that bridge, they would be in a constant state of alarm. Yet hundreds of thousands of commuters cross the bridge every day.

You suggest that a warning from sensors might prompt you to work at home? Then, knowing the bridge is in that condition, why do you come to work?  What added value would sensors add to this equation?  (All in all, I'd feel safer any day on the existing Bay Bridge than I would on, say, the Brooklyn Bridge. The Bay Bridge is not about to fall down. And there's no guarantee a strong quake wouldn't take out the new bridge either.)

Full disclosure: Yes, I'm among those skeptics who thought it would have made more sense to spend $6 billion on improving the schools or feeding the poor than on building a new bridge, which hasn't even opened and is already beset by nagging engineering issues that, no doubt, would be setting off the sensors left and right.  

Speaking of working at home, why do we even need to build such expensive and impractical infrastructure when we're moving towards a world where most workers can do their jobs remotely?

 

 

 

 

 

 

Susan Rambo
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Re: Bridge safety
Susan Rambo   7/20/2013 9:28:30 PM
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Tom, I don't know about you, but as someone who every work day rides twice over a major bridge in an earthquake zone -- and a bridge that is known to be not only unsafe in an earthquake but also prone to having things snap off it and land on cars --  I wouldn't mind knowing whether the bridge was feeling weak and under the weather on a certain day. (Sorry to anthropomorphize.)  I'd simply avoid it and maybe work from home, just as I avoid it when there's a major accident. It could also help lighten the traffic load on the bridge. Sure maybe the bridge's data always show it is near collapse. But with the media attention this bridge gets, it would be good to give the public access to the data. I'd like to say the media attention would get the bridge fixed quickly, but it's taken over 20 years to get part of the bridge rebuilt.  All I'm saying is many people who commute over bridges are watching to see what the traffic will be like every morning, so it's not a stretch that some of them might care to know how the bridge is doing structurally. 

_hm
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CEO
False positive and false negative
_hm   7/20/2013 8:39:31 PM
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MEMS technology and other contempprary sensing technology is welcome to solve new problems. Fiber sensor also has very good potential.

But it is also nice to see practical applications in work. There will be cases of false positive and false negative. One needs to analyze and take intelligent conclusion.

Another aspect is wherewithal of government to take corrective decision. More often, the deterioration is quite with tactile feedback and know to most of common person.

Tom Murphy
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Bridge safety
Tom Murphy   7/20/2013 7:17:58 PM
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With tens of thousands of structurally deficient bridges in the US alone (never mind the shaky freeway overpasses, weak tunnel walls, and dubious structures), I don't think we really need a lot of sensors to warn of a potential collapse. Periodic inspections should do the trick. Besides, would you really want the morning commute traffic report to include warnings from the bridges on various routes?

Susan Rambo
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Re: Safer bridges
Susan Rambo   7/20/2013 12:36:10 PM
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Sanjib.A Indian Railways does sound like an excellent opportunity to design a large MEMS-based monitoring system. Interesting. Is anyone working on adding MEMS to railway bridges in Indian?

Sanjib.A
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CEO
Re: Safer bridges
Sanjib.A   7/20/2013 12:07:56 PM
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This is a great application! In India, the first customer that comes to my mind is "Indian Railways", which is Asia's largest railway network and world's second largest network. I was reading in some article that by 2016, Indian Railways could have the highest numbers of bridges in the world. If not the highest, but still the number is impressively large. Hence it could be a big opportunity for this kind of application at the same time making  travel safer for so many people.

Susan Rambo
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Safer bridges
Susan Rambo   7/20/2013 11:30:12 AM
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What would these MEMS sensors do in an earthquake? Obviously you wouldn't need them to detect the quake, but I'm curious if the MEMS would produce any interesting data. Probably the data they return post quake will be invaluable.

These would be useful on bridges that face the marine environment along with seismic issues, such as this high-profile, problem-prone construction project (with its own website!).

 

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