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Computers guide traffic lights to reduce congestion for commuters, other drivers

(James Thrasher)

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Picture a wagon wheel. A computer will sit at the hub, but another computer will sit where each spoke meets the rim. Each rim computer will talk, in turn, to the 15 to 20 traffic signals under its command. All of those computers also will talk with the others on the rim, so if one fails another can pick up its load.

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With all the cycle and split knowledge stored in the rim computers, the primary role of the hub computer will be to synchronize the rim computers' clocks, receive status updates from the network and handle unanticipated "situational management."

"If I lost communication [with the traffic signals] for a day and a half under the new system, the motorist never even would have noticed," said Emil Wolanin, the county's chief traffic engineer.

Switching from old to new is a complicated process. Begun two years ago, the new system was initially expected to be completed in 2014, but after November's debacle County Executive Isiah Leggett promised the money would be found to get it done much sooner.

What's the future?

You may not know that loops of wire under the pavement at many intersections already note the passing of every car. If you knew the sharpness of the nearly ubiquitous intersection cameras, you'd floss more often. When there's a backup, traffic systems know how many cycles it takes you get through the light.

One day not too far off, the computer in your car will feed them more useful information.

No, you're not the first person to raise the privacy issue. It's very much out there. For the moment, however, let's just look at the technology under development.

Right now you may have a Global Positioning System device that communicates with satellites in real time as you drive. Soon your car's own computer will be able to gather GPS information and data of all sorts and share that with all the cars around you and with traffic control signals.

You'll get feedback. It will warn you of dangers -- cars too close or too fast -- and suggest alternate routes when congestion lies ahead, as many GPS systems already do.

And it will give traffic flow experts a wealth of information they've never had before.

Now, for example, cameras tell them how many cars are backed up at an intersection. Soon they'll know how many people are in those cars. (Think about why your seat belt alarm goes off. Same technology.) And they'll know whether a bus is empty or standing-room-only.

That knowledge will allow signal-split changes to promote the rapid flow of people, not just vehicles. A crowded bus gets a priority green, an empty one waits with you.


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