Now you know

But detecting the fact that you're sitting at the intersection can affect the time you wait for a light to change, said Town Engineer Craig Civalier.

The optical detectors replace what Civalier calls "loop detectors," which are in the pavement. All 10 of Oro Valley's intersections operate with the cameras. Future intersections will as well, he said.

The cameras are "a method to detect traffic, and they're easy to maintain," Civalier said. "This is just a more advanced way to regulate the traffic."

Cameras are more effective than older technology like the loops, Civalier said.

Loops operate on an electromagnetic field system that a car disrupts when it is waiting at an intersection, he said.

"The loops used to break and when you pave a road, you have to redo the loops. The cameras are easier all the way around."

The cameras help with waiting times at lights because they trip a signal when they detect cars and — unlike loops — bikes, Civalier said.

"If you're going northbound on Oracle Road, there's a certain amount of green time for northbound traffic," he said. "If it doesn't detect traffic from the north, it will advance the timing so the green time doesn't max out."

The cameras are capable of taking pictures and even video, but "we don't use it for that," Civalier said.

Timing of the lights could also be controlled remotely through the camera system. In the future, town officials may work with the city of Tucson to have the intersections in Oro Valley on the same system.

Tell us about it

● Ever wonder about that pile of junk cars taking up space on the corner of that major intersection for as long as you can remember? And what's that new business moving in at the shopping center you drive past every day on your way to work?

We'll find out.

E-mail us questions about things around the Northwest Side that have you scratching your head, and we'll do some research, then write about them in this space. Send inquiries to tkjos@azstarnet.com.