Tag Archives: overhead detection

What will detect cars at new PO traffic signals?


The in basket: The traffic signal in downtown Port Orchard seems still be operating on a timer while the state waits for the new signal poles, cross-arms and signals to be installed. 

I wondered if traffic detection there would be by in-pavement wires when the new signals go in, or would the state emulate Kitsap County and use the video cameras it’s using at more and more intersections lately. The cameras are mounted atop thin poles on the signal cross-arms and detect motion, not metal mass, as the in-pavement wires do.

The county says the overhead detectors are less costly to repair, and can remain in service when some project requires tearing up the pavement at a signalized intersection.

The out basket: Don Anders of the Olympic Region signal shop said Bay Street, also called Highway 166, which was just repaved, will have in-pavement wires restored, but detection of traffic on Sidney Avenue will be by video camera.

“The pavement loops are still the most cost effective detection system

available, and if installed under the top course of asphalt, they will

last for many years,” he said. “Video detection has improved over the past several

years but can be difficult to set up and aim. These units still have

some issues with missing calls (not reacting to waiting cars) in various conditions, and the cost is much higher.

“The reason we are using video on the side roads on the (Highway) 166 project is

that the side roads are city streets and the pavement is bad. The

pavement outside our right of way will not be repaired as part of our contract,

but will be later by the city. 

“We currently use video detection at several locations throughout the

region where we have poor asphalt conditions or the traffic volumes are

so high it is very difficult to maintain the loops,” Don said. “We will continue to

use loops as the primary method of detection because of the overall

cost, but I would guess that as the technology improves this may change

in the future.” 

Kitsap County public works, which is making liberal use of the overhead detectors, doesn’t agree about the cost difference, incidentally. Jeff Shea of that department, using the term “loop” to mean in-pavement wiring, says, “To install the loops in the road is about $1,200 per loop. You need four loops per leg times four legs per intersection, which totals about $19,200 per intersection in the ground. That’s comparable to the cost of video detection which runs around $4,000 per camera plus installation times four legs.”