Most of the intersections in Austin where there is a problem with the sensors have pedestrian lights and I just ride up on the sidewalk and hit the pedestrian button. Not much help for a left turn lane, though.

Don in Austin

They don't require any steel at all to trigger... they're inductive, not magnetic. Road crew I used to have to deal with on these used an un-laced Mavic MA-2 as a test target. Properly adjusted, an inductive loop can detect a single aluminum rim placed properly over the most sensitive part of the loop. Some will even detect just the aluminum brake track on a composite wheel.

But the smaller the inductive target, the more critical placement becomes, and the more important it is for the loop to be properly adjusted.

The solution in Washington State was legislative -- state law now mandates adjusting signal detectors for bicycles, and marking the most sensitive part of the loop.


Bicycle Detector Pavement Marking MUTCD Fig. 9C-7 by joshua_putnam, on Flickr




Bicycle Signal Loop Layout, Bellevue WA by joshua_putnam, on Flickr

I imagine you knew which one to use, but lets face it, many others (some here) would not know. And you forgot the face in your post.

Just be glad, one intersection I cross each work day has square cuts with hex cuts (how old must that be). Only a couple of newly repaved roads have the round cuts here, and they still do not adjust the sensitivity of those for cyclist.

That's great. I approached a local legislator about this issue in 2008. He bills himself as the cycling state senator. Sadly, he didn't see any need to improve our standards. Maybe now that WA has done it we can do it here.

Better to use an aluminum mtb wheel with fat tire on. The closer the rim is to the sensor the better it works, a bare rim will be too close.

Locally (quadrupole type) the best result I get is with my CF roadbike, aluminim rims with 23c tires. My steel mtb with Al rims and fat tires misses a few my road bike always triggers.

I really did think that the hex shape was a newer design. At a couple of local intersections where the dissimilar loops exist and don't overlap well, I tend to get frustrated as to which is which and either run the light or walk over and push the button. Or a car comes along... so my application of scientific method to see exactly what works... has been pretty slim.

Where single well defined loops exist, I can often trigger those with little problem. But I do know of some that just don't detect cyclists. My neighbor rides a motor cycle and one morning we both sat at one of those odd double loop (old and new) locations and he looked to me and said, "about half the time I get it to work." We both shook our heads and laughed.

It was a case where bicyclists and motorcyclists worked together for the change -- motorcycles often have the same issues with improperly-adjusted sensors.

You can find the relevant Washington code at
https://apps.leg.wa.gov/rcw/default.aspx?cite=47.36.025

Of course, Oregon's mandatory bike lane law might throw a wrench in the works, where bike lanes are run up to the intersection but the sensor does not detect within the bike lane. That's the case coming the other direction at the same intersection pictured above -- the bike lane continues to the intersection, but a bicycle must be in the center of the general travel lane to trigger the signal.

Hit the crossing button or let the cars cycle it. It's bad enough that some drivers pull up to the line fast to trigger the emergency clycling.

Fine...

Now consider that center lane turning patternd have changed dramatically in the last 3-5 years alone and now the signals either automatically cycle though every needed turn pattern or allow left turns when traffic allows or even allow U-turns at the intersection...the only option is to obey the switching patterns and keep yourself unwrinkled.

I can weigh 300 lbs fully overloaded with groceries and that sensor woouldn't send an email update it I subscribed

im not sure if someone said this already but having a neodymium magnet attached to your bike will alter the electromagnetic field in a way that triggers the sensor
https://www.wikihow.com/Trigger-Green-Traffic-Lights

It's been many years since I've seen anyone get out of a car and push the ped button in order to trigger a signal light change, plus it's a real pain in the ass when one is in the LTO lane with no motor vehicles behind the cyclist to aid in triggering the light. I just emailed our local DOT a few days ago on a LTO light not detecting a bicycle, no reply so far.

It does not appear that you understand how inductance sensors actually work.

They do and don't just as much. What I said is that here some drivers rush the intersection to trigger the emergency switching that is there to prevent accidents ON PURPOSE.

And if the intersection is on a set pattern for flow control...you'll go when it releases the other traffic. That is the way it is downtown, even if it's only a few square blocks.

When you live within 30 miles of a metropolitan area like Ada and Canyon counties in Idaho and their drivers are over here quite a lot, you get their brand of traffic controls as you have to.

if you think we might be Mayberry USA you oughtta be on the roads at rush hour and lunchtime...NASTY.

And that intersection they force? SW 4th St and SW 4th Avenue-the corner where City Hall is and the police department.

Hmm?

I had a light that wouldn't change for me on a bad intersection. I called the town and an engineer met me there the next day. He adjusted the sensor so my bike would trip it.

Sorry but you've fail both questions. It doesn't matter how much steel you have to trip an induction loop. I haven't owned a steel bike since 2003 and I've had no problems tripping lights in the 26 states I've ridden in since then. Dr. Goodridge explains it nicely here. It's about moving a conduction substance through a magnetic field and measuring the current differences which trigger the light. If you are lined up in the proper area for the light, you'll trip it. Finding that "proper area" can be tricky but not impossible as long as you can see where the wires are. In Genec's case, the proper place would be where the wires leave the loop and head to the switch box. Since there are multiple loops, it might be hard to find the live loop but I would suggest trying one until he finds the right one.

As for proceeding on the red when the light is malfunctioning, every state has rules to govern this problem. You don't have to sit at the light forever waiting for it to change. You are allowed to proceed after waiting a reasonable amount of time for a malfunctioning light...and a light that you can't trigger is malfunctioning. If you can't trigger a light with the induction loop...it does happen...you can wait a cycle or 2 (about 2 minutes per cycle) and proceed with caution.

The problem isn't the light but the position of the motorcycle...or bicycle. Your carbon bike has wheels of some kind, I assume. Your wheels are what trigger the system, not the metal in the bike. Read the link I provided above for an explanation of how this works. It works for aluminum rims quite nicely and, based on some rather scary moments in a thunderstorm with a carbon fiber fly rod in my hand, I'd suspect that it would work with carbon fiber wheels as well. Trust me, the carbon fiber is conductive

Can you explain what you mean by this? It sounds like you are saying that if you approach a traffic light at high speed, it will automatically change green. ???

No, it won't... but drivers hold to mind many myths. Some driver even think bikes should be on sidewalks. LOL

Emergency lights are triggered either by a special strobe on the emergency vehicle or an RF signal, neither of which is a rush at high speed toward the light.

My thoughts exactly. That's why I asked for an explanation. Maybe I was misunderstanding Rollfast's post.

CF rims do not conduct as well as aluminum rims, but a properly-adjusted sensor can detect just the aluminum brake tracks embedded in a CF rim for rim brakes.

But proper adjustment is important. Some jurisdictions will intentionally set a detector to be less sensitive, to avoid false positives from heavy trucks in the next lane. It's possible to set the signal so insensitive that it won't pick up a motorcycle. That's why the legislative solution in Washington State requires both marking the sensor sweet spot and adjusting the sensor to detect bicycles if possible.

None of the intersections I normally ride through are on set patterns other than basic 4-way intersections without dedicated turn lanes, where having a sensor isn't necessary.

Weight and mass are unimportant, as others have noted, inductive signal controls detect electrical conductivity, and a standard bicycle rim is an excellent target.

Other signals use video detection... properly adjusted, they will reliably detect bicycles or just pedestrians.

Why did I get a notice that I was quoted, anyway?

That's weird.

I would not say 'some' jurisdictions set the loops to be less sensitive but would say that all do it to avoid just the problem you detail.

I realize that you probably a member of the choir but the problem is that people don't position themselves properly on either vehicle. You have to have the wheels directly over the most sensitive part of the loop. For a figure 8 sensor, that means being directly over the middle wire. For the round detectors, that means being over the wire that leads from the loop to the box. In both cases, those wires are a double wire which increases the sensitivity greatly. If you learn how to do it properly, you can amaze people with your magical abilities. Some will even think you a god

New BF feature.

And it is quotes that you replied too.

State of Hawaii and the City of Honolulu adjust the sensors such that they do not dectect cyclist even if you are on the sweet spot. You can even increase your likelyhood of tripping the sensor by picking up the front wheel and swinging the wheel left and right over the sweet spot. That still does not work most of the time in Hawaii.

If think it is an operator problem, I can trip all of the sensors on the military bases here.

There have been a couple of times when I have been able to trip state or city lights, that is until they come around and readjust the sensor.