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Intersection detection doesn't notice me, what should I do?

Bicycles Asked by Dmitry Chornyi on March 11, 2021

I have just come to the USA (Bay Area) and got a bicycle to commute to my university. Being new to this place I kept wondering why sometimes I have to wait for a long time for a green light to make a left turn, and then a car comes along and the signal switches to green in ten seconds. Today I waited for a green light for five minutes and it did not come, since there were no cars in my lane. I started thinking I was insane, but then found this: How do Traffic Lights Notice Bicyclists? Sure enough, there are cameras in the intersection.

So how do people deal with this? Wait for a car? Turn on the red light? Use the pedestrian style of making left turns? Wave to the camera?

5 Answers

In most states it's the law that if the signal is malfunctioning you can proceed through "with caution" against the signal. Forester and others have argued that if a signal does not appropriately recognize the presence of a bike it's "malfunctioning" and you're on reasonably firm legal ground to invoke the "malfunctioning signal" provision. (However, I've never heard of this being tested in court.)

Do note that the presence of a camera does not necessarily mean that the signal is video-controlled. It may be that the cameras are there for general traffic monitoring, and the signal is still triggered by buried loop, radar detector, etc. Also, often there are sensors installed for detecting oncoming emergency vehicles that look a little like a camera but are not.

If it is a buried loop you can usually tell by observing the cuts in the pavement where the loop was installed (though of course a buried loop may be subsequently converted to video control). But with a buried loop the best place for the bike, to optimize detection, is more or less directly over one side of the loop, vs being in the middle of the loop. (As a last resort, lay your bike down over one side of the loop. I used to deal with one intersection where I could trigger the signal by just leaning the bike to about 45 degrees.) Note that a steel bike will usually be more effective than an aluminum one, and a carbon fiber bike is unlikely to be detected at all.

Correct answer by Daniel R Hicks on March 11, 2021

Cameras can also be red light cameras. Loops detectors can have smooth pavement. You may be able to figure out which cameras are definitely for signal control, though. I know in my area it's a very different style of camera placed in a different location than the red-light and emergency vehicle priority detection cameras.

Assuming it is a camera-controlled intersection:

  • If there's a little cycle symbol with lines put your tires on the lines. That's where the system is looking for a bicycle.
  • Be in the center of the lane, not the edge. The cameras are looking in a specific area for each lane, and if you're at the edge you might not register at all. Be where the camera is looking for a car.
  • Be bigger. Wave your arms. Take off your jacket and wave that. If you have a light, shine that up at the camera.

If none of that works, depending on the exact details:

  • If green for straight:
    • go straight through the intersection, pull over at curb and push pedestrian signal
    • go straight partway through the intersection, pull into the crosswalk on the right and flip your bike 90 degrees so that you're now at the front of the appropriate going straight lane for the direction you originally would've turned into. Smile and wave cheerfully at the confused car driver that's now behind you. (it's a "box turn")
  • If red for straight:
    • Right curb is easier/safer (can see cars behind you), so go over to right curb. Push both pedestrian signals and do the pedestrian 2-crossing left turn or a pedestrian style box turn
    • If you can see any potential directions somebody would turn into the oncoming lane, you can go across to the left curb, in which case you should be able to just push one pedestrian button and start pedaling off when you're most of the way across in the crosswalk.
  • If you're feeling brave and everything is totally clear for miles: proceed through the light (after stopping). I didn't bother digging up the exact california law, but the california driver's handbook basically says a malfunctioning signal should be treated like a 4-way stop. The part where the signal is only malfunctioning for one specific lane isn't really well-covered, though.

If a signal isn't picking you up, it's malfunctioning and needs to be fixed. It's a hazard. Note the exact location, day of week and time of day, and report the hazard.

You didn't say exactly where in the bay area you are. However, East Bay Bicycle Coalition and Sonoma County Bicycle Coalition have hazard reporting systems on their sites. Silicon Valley Bicycle Coalition and Marin County Bicycle Coalition have guides to help you figure out who to call.

Answered by freiheit on March 11, 2021

In L.A. you have visible coils in the asphalt to detect metal. it's used for red lights and traffic detection. enter image description here
(source: instructables.com)

on the bike lanes, there's smaller ones that are able to detect bikes.

when there's only the regular lanes, it will never detect a bike. what i do is if there's a car behind me, i stop on the pedestrian crossing area and hope the car will move forward and trigger the damn thing.

if there's no hope of that and i know it's one of the two take-forever-red-lights in my path, i just go directly to the pedestrian button on the side walk.

... scratch all that! just found a solution when looking for a picture to put here!

https://www.instructables.com/id/Trigger-GREEN-Traffic-Lights/

solution: magnets under the bike!

Answered by gcb on March 11, 2021

From http://www.ecovelo.info/2010/06/17/trigger-happy/ (written by Alan Barnard):

"You can often see evidence of loop detectors as lines cut into the road surface just behind the crosswalk. Wire sensors are embedded in these cut lines, and it’s possible to trigger a light by placing your bicycle wheels precisely on top of one of the wires to disrupt the magnetic field. Some sensors seem to be more sensitive than others; in those cases where the light isn’t initially triggered, I’ve had some success by leaning my bike over toward the inside of the detector loop. In cases where there are two side-by-side loops, lining up over the center where the two loops meet doubles your chances of triggering the light. Once I understood exactly how loop detectors work, my rate of success at triggering lights considerably improved; I’m currently getting somewhere approaching a 90% success rate on the detectors where I live."

There are a lot of interesting comments there, also!

Hope it helps

Answered by heltonbiker on March 11, 2021

After using the other advices, to help yourself, you should inform the authorities about the malfunctioning, nonfunctioning device.

Think about other cyclists, which don't know what to do as well.

Can it be, that street planning is done without modern bicycles in mind? If an accident occurs, they shall feel guilty! But better: They should rework their technique, and choose another approach.

Answered by user unknown on March 11, 2021

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