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Cameras measure traffic flow, not speed
Sensors pop up along Pilgrim Mill
traffic cameras 2 jd
After this signal has been activated, the motion sensing camera mounted next to it will tell the system when a car is waiting for the light to change. - photo by Jim Dean

They may stir worries of a speed trap, but the cameras above two Pilgrim Mill/Atlanta Road intersections are actually there to help traffic flow, officials say.

The closed-circuit cameras read the number of vehicles in a given lane and alert the traffic signal computer when it’s time for the signal to turn green, according to the state Department of Transportation.

The sensors are an alternative to the more commonly used loops positioned underground before a traffic light.

Teri Pope, spokeswoman for DOT, said the cameras "do not have a recording tape."

“They are positioned so they only see the front end of the vehicles," Pope said. "We’re not capturing tag numbers or anything like that. It’s purely for traffic control signals.”

The traffic sensors, positioned where the state route crosses East Maple Street and Pirkle Ferry Road, are a first for Cumming.

They are the latest addition to an $885,000 project to turn Pilgrim Mill/Atlanta Road into a two-way street near downtown.

City Administrator Gerald Blackburn said it’s a city project, but the transportation department insisted on the cameras.

“It’s a new requirement that [we’re] using in lieu of the underground sensors,” he said. “It makes sense just simply because the underground sensors, after they’re put in, a lot of intersections ... have to be resurfaced.”

Pope said the sensors, which rest on the traffic signal poles, cost about three times as much as the underground loops.

Because they occupy less space, however, the sensors are preferred in urban and more confined intersections. And over time, she said, they can actually save money.

“When we’re saying it’s three times the cost, that does not include the additional right of way cost to buy the additional land at the intersection,” she said.

“The cameras require a lot less maintenance and are usually a lot more reliable than the loops, because ... they receive a lot less damage.”

Jimmy Vaughan, engineer for the city, said many of the ground sensors have caused asphalt to shift, requiring repairs.

While the transportation department maintains the signals, the city would need to pay for road repairs.

“It could save in the future because you’re not going to have to repave the road as often,” he said.

The project, which was supposed to be completed before 2010, is running behind due to weather, Blackburn said.

With seemingly constant rain, construction has slowed. Even when the weather dries out, Blackburn said, the final touches could be delayed.

“It’s going to have to be warm enough to pour the final coat of asphalt,” he said, adding the project should be complete by the end of January.