Sensors Mag

Stop and Go Traffic

January 27, 2006 By: Melanie Martella, Sensors

Recently, drivers in Bentonville, AR, experienced traffic problems. To wit, the vehicle presence sensors embedded into the road to tell the traffic lights to change had been mangled in a construction incident. Construction equipment blithely severs important stuff? Not news. What was more interesting, at least to me, was this: officials didn't know that the reason for the traffic snarl-ups was a damaged sensor and they didn't know where it was.

A quick visit to How Stuff Works to find out how these devices operate tells me that an inductive loop sunk into the road is connected to the lights. Any vehicle stopping over the loop changes the inductance and this is communicated to the light, which can then change to green. (Unless you're in a hurry, in which case the light will take a really, really long time and after it changes you'll be stuck behind a driver going way under the speed limit and no passing zone for miles, but I digress.)

As I read the news story, I thought "what if the sensor had been a smart sensor and tied in to the traffic signal network?" In our traffic scenario, using a smart traffic sensor could mean finding out more quickly what's broken and where it is and that means moving traffic rather than cars at a standstill.

I understand, from some judicious Googling, that traffic sensor technology has improved beyond the basic inductive loop. There are now devices capable of providing a range of different traffic flow parameters rather than just vehicle presence or absence.

That's really the selling point of smart sensors. It's not that they're better at sensing, but the addition of smarts and communications is an enabling technology. Smart sensors enable easier and more efficient maintenance, configuration, and general operations because they provide more and better information, and information is power.

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