groth

More and more intersections in my area are being outfitted with traffic signal control cameras to replace the metal detectors in the road. I'm guessing there's an official name for these cameras other than traffic signal control cameras, but I don't know what it is. In any case, they sit on a stalk above the traffic signal that hangs out over the road and they are aimed right about where a vehicle would stop for the red light.

I've been suspicious that these cameras don't trigger on cyclists.

Today, I think I had a confirmation. I approach an intersection with a red light and stop. On the other side is a motorcycle stopped (pretty much the same frontal image as a cyclist). We are on the low traffic street and we only get the green light when the sensors detect us. In normal operation, when this light is triggered, the traffic going in the direction of the motorcycle gets a green light and a green left turn arrow while the traffic going in my direction waits. Then the left turn arrow goes away and there's a green light in both directions before it goes back to red.

So today, we waited and waited. Finally a car pulls up behind me. The light changes to green right away (after a short wait for the cross direction to cycle to yellow and red - I can see this). The motorcyclist did not get a green left turn arrow, which is what he wanted to do, so he waited. I'm pretty sure the camera never detected me and I'm almost positive it didn't detect the motorcycle.

I suppose I can believe the designers of these camera systems weren't thinking about cyclists, but surely they shouldn't forget about motorcycles!

In any case, does anyone know for sure how these detect vehicles? Do they really not detect cyclists and motorcycles? If so, what can we do about it?

Thanks,
Ed

rdtompki

I don't know that we use this technology in California, but even at intersections which are designed to detect bicycles I haven't seen evidence that the sensors detect CF bikes.

B. Carfree

These sensors can be set to see bicycles, but the folks who set them up are usually quite reluctant to set then that sensitive. Get in contact with the traffic engineer who is in charge and see what s/he will do. If that doesn't get any traction, go the elected official route.

CommuteCommando

I commute in SoCal and in Orange county they are pretty common. Most work for me, some don't. I pull up to the intersection, and stick my arms out to the side and do a slow motion, like jumping jacks. Don't know if it helps, but it probably doesn't hurt. It may make me look silly, but I am at least twenty years past caring what strangers think.

One intersection that the sensor doesn't work at doesn't seem to respond to anything except pushing the dam button. I hate pushing crosswalk buttons.

Most of my commute is in Irvine, which is a pretty bike freindly city, and theirs almost all work for me, except one.

Terex

Camera? Thought it was a buried inductive loop under the roadway. But you may have fancy controllers in Pennington. I live nearby, and the inductive loops don't detect my Miata, let alone a bike.

You sure you got cameras?

decosse

Some cameras definitely can catch bikes. There are many here in Las Vegas that do, and one in particular I really like. It's on an intersection of 2 streets which both have bike lanes. I can be the only vehicle on the street, switch over to the left turn lane, and it always turns green before I get there. I can keep pedaling in a higher gear and keep my momentum for going uphill after the turn. It does help for me to get in that turn lane as early as possible to give it a chance to "see" me

Jseis 

The traffic light at the north end of the Astoria-Megler Bridge will trip with two (side by side) aluminum bikes stopped at the stop bar. but not one. Never tried single file.

catonec 

I guess I never thought that those cameras were meant to trigger traffic lights. I always assumed they are "big brothers" eyes used for law enforcement and terrorism prevention. I watch alot of cop shows on tv.

howeeee

I think some you are confusing cameras with electric eyes(sensor),,,some states have cameras that take pictures of the plate numbers of cars that run the light and they are sent a ticket. The electric eyes trigger lights depending on if there are cars or not sitting at the intersection they are not camera's.

CommuteCommando

Inductive loops seem to be being phased out around here. Those were pretty reliable. The optical sensors probably have the advantage of not being suceptable to road wear from heavy trucks, etc. At a couple of intersections with opticals you can still see where the indiction loops were buried, but it is pretty obvious they on not functional. I went over one today where the wires were even exposed through busted pavement.

Carbonfiberboy 

Correct. It's not done by cameras. I've contacted the engineers here with some success. If you can see the tar lines over the sensor, position your bike's wheels directly over the forward end of the right hand line or the right side of the circle if there is one. They detect the wheels, not the frame material no matter what it is. However many detectors are set too light to see a bike, and many times they've paved over the tar lines so you can't see them. They're afraid of detecting traffic in the next lane over. This is especially irritating in left turn lanes, when you won't get the light and it's hard to tell when it's safe to turn. Many times in that situation there are no crosswalks so you can act like a ped, either. Sometimes you can get off the bike, lay it down, and wave it around over the road. That's what the engineers will tell you to do.

In some cities, they've created bike symbols to show you exactly where to position your bike. That's nice.

B. Carfree

Last year San Jose, CA was trialing a signal-mounted sensor that would not only detect bikes but would also change the duration of the green light for them. If it detected only a motor vehicle, it gave a green light for just a few seconds. If it detected a bike, it gave a longer green light (I don't remember how long).

I haven't heard anything regarding how the trial turned out, but it was nice to see something happening in the way of traffic engineering that was an actual solution to a problem cyclists have. The main entrance to the local university from the main bike path along the river involves a signalized crossing of eight lanes of traffic (three each way plus a left turn lane plus a bus lane). The green light, which takes 85 seconds to trigger, lasts four seconds. There have been deaths here when motorists have entered the intersection while a cyclist was still crossing. (One does not have the right of way even with a green light if the intersection is occupied by someone who entered it legally, but most motorists don't know that.)

volosong

Here in the Antelope Valley, there are twin cities with just a mile or two of open space between them. None of the signals in Lancaster will detect bicycles or my Vespa. The signals in Palmdale where I live have been set to detect bicycles, even my CF bike.

Thanks for the reminder. I need to contact my traffic department and let them know that I appreciate them setting the signals so that my bike will trigger them. (I contacted the Lancaster traffic department and have not heard anything from them, even though they are supposed to reply within two weeks of a report being submitted.)

groth

The metal detectors (loops in the road) seem to be on the way out.

The particular intersection I was referring to is Cleveland Lane/Rosedale Rd at Elm Rd in Princeton.

Pennington just redid its only intersection with a traffic light. Besides wheelchair cutouts and repaving, cameras appeared atop the lights for Delaware avenue.

- Ed

Wogster

I don't think it's a camera, it's a motion sensor. Most motion sensors have a lens to set the detection area, it's possible that it's set narrow, with the idea that a car will cover that zone, as long as it's somewhere in the lane. Say it's centred on the lane and 2' wide, a bicycle is typically too far right in the lane to trigger it, and a motorcycle is typically too far left to trigger the sensor. They set it narrow so that vehicles in other lanes don't trigger the sensor. A simple solution is to set the sensor wider, another solution is to mark the centre of the sensor area on the pavement. Bicycle and motorcycle riders, simply need to be within the marked area.

roccobike

Their official name is Control Camera but their engineering terminology is "Defective/Malfunctioning" as they frequently are not set up correctly and are prone to not working due to sunlight glare. Law enforcement and the manufacturers will argue but these cameras are no match to the more reliable metal strips. I think control cameras are not legal in some states, could be wrong about that.

Looigi

Those "motion sensors" with white plastic faces as used to turn on lights when you enter a room or trip a burglar alarm are essentially very low resolution infrared cameras, equivalent to a handful of pixels. There's no reason cameras and computing power can't be used very well for the purpose of controlling traffic lights. The cost now is likely way less than burying and maintain loops in the pavement so I'd expect to see them proliferate. Of course there are likely to be a few bugs and updates before they're working reliably.

Wogster

I can't see a traffic control camera being much more then a motion sensor, it's not like your going to use a high resolution camera and check through a database of car and truck pictures looking for a match. It's more likely looking for something to move through a 2'x2' area, just behind the stop line. If the area was say 8'x8' then there would be too much of a chance that a camera not set quite right could "see" motion in another lane or someone in a crosswalk or on a sidewalk, triggering the light, when it's not needed.

There are other issues, one is will the sensor work in say a heavy snow storm, which a motion loop sometimes has trouble with.

dynodonn 

What the OP is thinking that are cameras, could be sensors that some emergency vehicles operators can use to change signal lights quicker, and well before they reach the detection loop.

decosse

These are the best articles I could find with a quick search. As stoplights here in town are upgraded to LED, they are adding these sensors... When they first put in cameras and camera/sensors here it was all over the news. There was a big uproar, with the city assuring people that they were not red-light cameras.

From a local attorney's page on Av vo website-

"...Algorithms that detect changes in the pixel patterns to control traffic signals. New designs have begun to use cameras for sensors. These detectors are often placed on a signal arm in the intersection. They cover approach areas to the intersection. Software within the control system analyzes the graphic image captured by the camera. A detector identifying the presence of a vehicle uses algorithms that detect changes in the pixel patterns to control traffic signals...".

And from city of Regina-


Traffic Light Sensors – How do they work?

By Dan Wednesday December 19, 2012


Traffic lights, like our smartphones, are being upgraded with newer and newer technology to help getting from A to B safer and faster. Most urban cities now have new sensors and cameras on their lights, but we might be asking ourselves, “How do they work?”......
To help answer these questions, we contacted Harvey Turner, Traffic Signal Systems Analyst with the City of Regina, to learn about the three types of sensors you can find in and around the city.

Video Camera Sensors
Video camera sensors are the most commonly used in the city and look like a small metal tube perched just above traffic signals. These cameras face on-coming traffic and watch for changes between its “learned” background image (what the intersection looks like when it’s empty) and the live image. If a car pulls up to a detection zone (generally just behind the stop line), the traffic control computer notes the change in images and responds by changing the signal cycle appropriately. This might mean adding an advanced green, giving a waiting car the green light, or skipping a cycle for an empty intersection.



- See more at: https://capitaltailgate.com/traffic-l....6fifuWZB.dpuf

Looigi

Perhaps. My cell phone identifies faces and recolonizes my friends and family. A simple cheap type camera (think $10 webcam) can be used to identify shapes, sizes and motion of items in its FOV. Two separated by a specific distance can determine distance and speed. The cost of the cameras in inconsequential and the cost of the necessary computing power is also very cheap nowadays. So I'm sticking to my story....

John_V 

It's nice to see bike friendly cities getting this type of technologies to help cyclists on the roadways. Here in Central Florida, many of the cities are using cameras and traffic sensors for increased revenue. And they are doing it the dirty way. One of the local news stations exposed that many of the cities are shortening the length of time that the traffic lights stay yellow and they are all at intersections with cameras. Not only are they citing more "red light runners" but they are also causing more intersection traffic crashes than before the cameras were installed. Gotta' love our government.

Terex

Yep. I'd been away from NJ for a while, and was driving up Rt. 1 in Edison. Cruising through the light, that for the last 10 years had stayed yellow for about 30 min., suddenly the light changed to red and I saw a flash from a pole mounted camera. Haven't seen any tickets in the mail yet, but it's obvious that they put in ticketing cameras AND shortened the yellow cycle time.

Wogster

I spent 30 years in the computer business, simplest is to have the camera capture an image, compare that to a reference image, because the logic is fairly simple. It's not as simple as it could be, because you want to eliminate things like say a bird or piece of garbage. It comes down to the specifications. Say your engineer is worshipping the cult of the car. They might set the camera to say a 3' x 3' FOV, and require that ALL pixels be changed, from the reference image. That would also not be triggered by a bicycle or motorycle, but would be triggered by a car. It might not be triggered by a small car in the wrong lane position.

lhbernhardt

These optical sensors are appearing at more traffic lights around the Greater Vancouver area. Most of them don't detect bikes. My rule of thumb is that if the light hasn't changed within a reasonable length of time, and there is no traffic, I assume it's a defective sensor and I proceed on the red.

The ones that do detect bikes usually work with the bike in a specific position, like in the middle of the lane and right up against the crosswalk. They DO NOT respond to light (pointing your 500+ lumen headlight at it does nothing).

I have heard that angling your bike sideways (at right angles to the traffic) so that it covers the same space as the front of a car is supposed to work. I've tried it once and it didn't.

Another strategy (when there is no traffic around to trip the light for you) is to enter the car lane early, assuming the sensor picks up well ahead of the intersection and is not interfered with by peds walking across in the crosswalk.

I think the loop detectors were much easier to deal with (most bikes have a heavy steel mass that will usually trip the loop detectors; it's called a chain), but I would imagine that the technology will improve sufficiently for bikes to be accommodated. At this point, you just have to try different things to see if they trip the lights.

Luis