eepok

Hi all,

I have a weight weenie buddy who, now that he's invested in carbon wheels, is finally listening to me about triggering traffic signals.

• Quick Aside: I've seen a number of threads where many people don't understand how traffic signals are actuated. Here's a quick rundown:
  • Some traffic signals may not have any detector and may switch purely on timing.
  • Some signalized intersections have bike buttons on the side of the road. These are OK solutions if you're going straight and there's no one trying to turn right, but useless if you're trying to turn left or there's a right-turn-only lane in the way.
  • Inductive Loops run a constant current just below the asphalt surface. When something metallic comes close enough, it shorts the current which tells the signal box that there's a "vehicle" there.
  • Intersections with camera detection sense the presence of a "vehicle" and puts that lane in line for a green.
  • Even better than video, you have microwave detection which senses through pretty much anything (fog, snow, rain, etc.)

Anyway, he's now trying to find some way to reliably trip the inductive loops in our town in his solo rides. I've read that running a closed-loop copper wire inside your rims can do it. That seems light enough to suffice, but I don't to suggest it unless someone's actually tried this with good results.

There's also something called the "Veloloop" that was on Kickstarter. There's no way he's going to bother with that.

Have any of you carbon nuts figured out a reliable solution to tripping inductive loops? Have you tried the copper wire option? Did it work?

WhyFi

If I can't trigger it and if there aren't any cars showing up to trigger it for me, I simply run the light (which happens to be lawful in MN, and many other places, I'd assume).

JasonD67

I ride an aluminum bike with aluminum wheels and never have been able to trigger lights that have inductive loops (at least in the area that I ride). Only options are wait for a car or run the light.

jitteringjr

If it's a busy intersection, I just roll over and hit the pedestrian crossing button and get back in the lane. If there is nobody around, I play it like whyfi.

TimothyH

Calling people "Carbon nuts" isn't a great way to start a thread and triggering traffic lights isn't even a consideration when I choose wheels.

Do inductive loops even work with aluminum? Many lights where I ride use cameras to detect vehicles.

I've heard that some motorcyclists use large rare earth magnets.

Bryan C. 

I do the same as above, wait a bit and then run the light when traffic is clear.

Thread from 2007 with some good information.

https://www.bikeforums.net/commuting...does-work.html

dorkypants

Aluminum rims can trigger inductive loops, if the loops are tuned to detect the smaller magnetic-field disruption they produce. In my area some loops aren't tuned for bicycles, but reporting the problem to the local municipal traffic department usually gets them to correct the problem.

Teamprovicycle

I didnt know crossing the street was so complicated and scientifical ....???!!!

79pmooney

In Oregon, it is not legal to run the light when you cannot trigger the sensor. (I do it a to and if I came before a judge, would consider playing the prejudice card, that sensors do not detect an entire class of vehicles and therefore do not give those citizens a means of crossing a public thoroughfare legally. I've been noticing these prejudices for 50 years in the 5 states I've lived in. It's getting kinda old.) The induction sensors can, I believe, be tuned for sensitivity. Sensors I have been riding over for years change periodically and are often significantly different after re-paves.

Portland has many sensors that work very well, but not everywhere. A left turn I take 200 times/year I can trigger maybe 1 in 10 times. That left is a far safer option than following the all bike-laned streets and moving left across traffic between lights at rush hour to take a left fork three blocks later. (The rest of the ride home is also on far less traveled streets and much better, safer riding despite no bike lanes. Also cleaner pavement.)

Ben

mcours2006

Yes. This.

eepok

Yep. It's the problem of differing state standards, grandfathered exceptions, and limited grants that allow one to upgrade the engineering/tech of a couple intersections, but then leave the rest in the past. The discontinuous standards on a single road makes it so that the "virtuous cyclist" has to become an amateur civil engineer to stay within the law.

In California, if cities do enough work to an intersection (renovate, modify, etc.), that intersection must be upgraded with Type-D inductive loops that allow a bicyclist to sit in a "box" that detects the bicycle instead of having to go tires-to-the-wires. You can tell black sealant on the ground obscuring the embedded wires. If it looks like a circle (or a square with its corners cut off) and has a diagonal line going through it, it's very likely a Type-D loop and just sitting inside the shape should trigger the signal. (More here: Detection of Bicycles at Demand-Actuated Traffic Signals)

It's kind of the issue within bicycling and engineering. Cities love to throw money at engineering because it's easy. You pay money, get plans drawn up, higher a contractor, contractor installs things-- job done. Education (telling people HOW to use stuff) is hard and its absolutely never ending because people don't care to learn until it affects them. Instead, cities tend to fall back on signage and stenciling, but signage must have so few words (and stenciling even fewer), that most people see it as hieroglyphics. (See: https://ggwash.org/view/6145/ddot-to...re-bike-signal )

Shimagnolo

There is one thing you didn't mention:
Some lights switch between timing and detection, based on time of day.
There is such a light at the main entrance of my housing addition.
If I roll up to it before 7am, or after 7pm, I can trigger it instantly.
Between 7am and 7pm, it totally ignores the detection loop, and just operates on a timer.

I also know of some other traffic lights in the area with detection loops that that not only won't detect a bicycle, but won't even detect my motorcycle!

Ogsarg

I had mixed success triggering them with a 600lb motorcycle with steel wheels so have some doubts there is anything you can do to reliably trigger them on a bike regardless of the wheel material. If you come up with something, you might have a marketable product.

Bah Humbug

There are places where there's no ped crossing, and where the lanes to cross to the right to get to one if it existed is four lanes wide. I just roll when it's safe at that intersection. No idea if it's legal in Texas.

Bah Humbug

And that one won't detect an aluminum bike and wheels.

Stormsedge

I hung a magnet from the frame of a motorcycle I once owned that didn't have enough iron in it to trigger the lights...probably not a great solution for someone concerned about the weight of their bike, however.

MSchott

There's one locally that never works for a bike. It's on a street that crosses a busy road but the cross road is not busy and I usually end up as the first vehicle. So far I've been able to signal cars behind me to move forward enough to trigger the sensor but some day I will just run the light and take my chances.

Carbonfiberboy 

Left turn lanes are the real PITA. No button to push. Aluminum rims work fine for loops if they're tuned for bikes. Magnets don't do anything. It's expensive to tune a loop for bikes. One city engineer estimated $1500/ea. Which explains why it's not often done. They have to send a full work crew, set up traffic diversions, cones, etc. and then actually do the tuning work, then take the diversions back down again without anyone getting injured. I've been advised by the city to lay the bike down flat for best detection, but tuned loops usually work for upright bikes.

But back to the OP: Heavy copper wire should work. You'd have to try it at intersections with loops known to work with aluminum rims. Around here camera detection is nonexistent. Only loops.

jwh20

Here in Indiana the legislature recently changed the law to cover "dead red lights" which covers most situations with bicycles. It allows a cyclist to continue through a "dead" red light after 120 seconds if it's safe to do so.

7.(b)(3)(D):

https://codes.findlaw.com/in/title-9...-9-21-3-7.html

CliffordK

Not exactly true.

Oregon 2015 Senate Bill 533:
https://gov.oregonlive.com/bill/2015/SB533/

Signed into law:

Oregon ORS 811.360 (2)

This law, of course, has several faults. For example, once one arrives at the light and waits for it to go through a full cycle and nothing happens, so one chooses to proceed when traffic clears...

Then the next time one approaches the intersection, does one have to wait again?

And, of course, it fails to note what one should do if a signal completely fails to cycle (dead red).

I have chosen to take a loose interpretation of the law. The law says absolutely NOTHING about timing. So, as long as I waited a full cycle... sometime... probably... then I consider that good enough.

And... if it shows signs of failing to cycle, that is also good enough.

CliffordK

Has he found signals that were specifically designed to be triggered by a bicycle (in either a bike lane, or with a bike symbol designated on the road) and verified whether or not it works?

In theory, carbon fiber is electrically conductive, so it may well trigger a well designed inductive loop.

Virtually all bikes will have at least a few bits of metal. Spokes, nipples, axles, nuts, bolts, brakes, pedal spindles, tools, tire valves, etc.

If the bike triggers some light triggers, but not others, then it is a fault of the trigger system, and not a fault of the bicycle.

DrIsotope

I trigger inductive loops all the time, on my carbon bike as well as my steel bike. The trick is to get into the lane as early as possible-- often 200-300 feet before the crosswalk. Dead-center, right in the middle of the lane. Most intersections have 3 loops per lane, spaced out. If you miss the first two and only trigger the one right at the "front," the timing circuit is going to wait for another vehicle to trip a loop, and if it doesn't get one its going to continue on it's timed cycle-- meaning you can sit there for a minute or more. If a single car is coming, wait until it passes and get right behind. The more loops simultaneously triggered, the faster the lights will cycle.

I mean, I guess it's possible that they've gone out of the way to set the loop sensitivity high enough to pick up bikes. I just know that missing the first loop or two means I'm going to have to wait... unless there's no cross-traffic, then I just go.

79pmooney

Thanks Cliff. I asked an officer a few years ago and was told it was illegal (then). He said if we were prudent, he would let it slide. I never realized the law had changed.

Ben

Beach Bob

Most of our newer intersections I'm told are working based on a thermal system. It sees the heat from an engine/cyclist and takes it from there. Much cheaper to implement than burying loops in the asphalt, and way, way easier to change when they fail. My experience is that they work really well except on hot days, where I may not have enough temperature differential to trip them.

DrIsotope