Tag Archives: traffic detectors

Stay over the detectors at traffic lights that are red

The in basket: Janine Barrie writes, impassionedly, “Please put the word out to all who are the first vehicle in the left turn lane. This problem has happened numerous times to me, but (last) week was the last straw. I need to complain to someone who might be able to help.

“I have been the second or third car from the white stop line in the left turn lane. The first car is 10 to 15 feet from the white line, and guess what happens, or should I say does not happen.


“That problem happened three times last week, and made me late for an appointment,” she said. “It happened on McWilliams in front of Safeway, on Central Valley at Fairgrounds and Central Valley at Bucklin. The first one mentioned was the worst and the longest wait.


The out basket: Unlike Janine, I rarely fall victim to such a clueless driver ahead of me. But for those drivers who don’t understand where traffic detector wires, called “loops,” are located in the pavement, and how they work, I’m happy to oblige.

The wires are imbedded in the pavement just behind the broad white stop bar at signalized intersections. You often can see the patched grooves into which they have been inserted. They detect the mass of a vehicle above them and inform the traffic signal that someone is waiting.

If a waiting driver at a red light doesn’t position his vehicle over the wires, the signal probably won’t react to the vehicle’s presence.

I occasionally do see some car pulled past the white stop bar, which inconveniences only that driver, and only until someone else pulls up behind, over the wires. If a driver doesn’t pull forward far enough to cover the wires, as Janine describes, there’s not much those behind can do except walk up to the driver and say to pull forward. Honking usually doesn’t convey the intended message.

Fortunately, I’m usually in another lane when I see this, and am not delayed by it. The last time I was behind a driver who stopped short of the wires, I finally got out to urge him forward … and the light changed before I got to the car. Then I became the problem, as I had to run back to my car, start it and proceed. I caused a bunch of drivers behind me to wait another full cycle, as I did. Evidently, the driver ahead of me wasn’t a far off the wires as I thought.

It’s hard to imagine would kind of bum luck would cause a person to run into this frustration three times in a week, as Janine says she did.

If you see a slender vertical pole with a camera-like device on the signal cross-arm ahead of you, the detectors are optical and you have more latitude as to where you can stop.

For both loops and optical detection there is a defined detection area,” says Jeff Shea, Kitsap County traffic engineer. “So the vehicle does have to be in a specific area, but with optical detection we can make that area bigger than some loop configurations.”

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.”

Traffic detection at Bethel and Lund avenues


The in basket: Mike DeMinter wrote in August to say, “A couple of days ago I noticed someone is working on the traffic  

lights at the Bethel/Lund intersection in Port Orchard.  Are they also going to reposition the left turn sensor that signifies traffic flow from Bethel onto Lund (towards Jackson Avenue)?


“When Lund was widened a few years ago, a right-turn lane was put in for cars that want to turn onto Bethel and progress towards the bowling alley,” he said. “The creation of the additional lane caused the white line markers on Bethel to be moved back. What was forgotten  

is the left turn sensor mentioned above.  It appears to have been  

left untouched.

“As it stands now, approximately three-fourths of the sensor 

wire is in front of the white line and thus not  usable.


“Consequently,” he said, “cars that want to make a left onto Lund must ‘snuggle up’ to the double-white line in order to be ‘sensed.’  Many times I have had to wait extraordinary lengths of time behind cautious drivers who stop a few feet behind the double white line and wait through several light changes until they finally realize what is going on and move up.”

Belinda Wright has a question about the same intersection. She was reading on the Road Warrior blog at kitsapsun.com  about the limitation on Bremerton’s red light enforcement cameras to only two directions of travel per intersection that they can monitor. 

“What look like cameras have been installed at Bethel and Lund in Port Orchard and it looks like they are pointing in all four directions. What’s up with that?” she asked.

The out basket: Jeff Shea, Kitsap County traffic engineer, without addressing Mike’s interpretation of what led to the problems, says “The traffic control box, which houses the electronics that runs the lights, was recently replaced. Many of the loops in this intersection are beginning to fail.”  

The county has replaced them with the new overhead traffic detection cameras, one for each direction. Those are what Belinda sees on the cross arms, not red light enforcement cameras. Only Bremerton has them and at only a handful of locations. They look nothing like the detection cameras and aren’t on the signal cross arms

The overhead cameras are gradually replacing the in-pavement detector loops because they can be repaired without tearing up the pavement and can remain in service when something else requires digging up the road surface.