Tag Archives: overhead traffic detectors

Overhead traffic detectors spotted on Highway 303

IMGP2319The in basket: Sharell Lee asks, “What are the new objects on the poles above the traffic lights at the intersection of Highway 303 and Brownsville Highway? They look like cameras, but there are no square boxes like at the intersection of Sylvan and Wheaton. What are they?”

Steve Van Wyk saw them too and asked, “What’s the deal with all the cameras that have been installed on Waaga Way and in Silverdale ? These things are now on virtually every stop-light stanchion.”

The out basket: They are overhead traffic detectors, used instead of the time-honored in-pavement wires that serve that function at most intersections.

Kitsap County has been using them at many of its intersections in Silverdale and South Kitsap for a few years. The state began using them three years ago, says Claudia Bingham-Baker, its spokeswoman for this region, and installs them as part of other projects, rather than wherever they have the wires. The project in this case is the paving work going on along 303.

I don’t recall seeing them on any other state signals here, but Claudia says these are a long way from the being first for the state.

They are preferred over the in-pavement wires, commonly called “loops,” because they are much easier to repair when they malfunction. Changes in the pixel pattern as vehicles arrive at a red light tell the light when it should change.

A commenter (see comments) on the Road Warrior blog at kitsapsun.com read the above and asked if the overhead detectors will be kinder to motorcycle and bicycle riders, who often don’t have the metal mass to be detected by the in-pavement wires.

Claudia said, “Yes, we think they do detect bicycles and motorcycles better than the loops. That would be especially true with bicycles built with carbon-fiber frames, since the loops depend on metal to detect vehicles.  Having said that, as you pointed out, the video detectors work by sensing contrast changes, so something like a deer could theoretically trigger them whereas that would not be an issue with the loops.”