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  1. #1
    Senior Member TuckertonRR's Avatar
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    Red light w/sensors

    Ok, there's this light near where I live which is automatically on "red" for both directions. Both directions operate via a sensor (either on top of the light/in the road??) when a car comes upon the light it changes to green for about 10 seconds, then cycles to amber,then red. It does this for all four directions at a standard 4way intersection. This also has buttons pedestrians can push to activate it as well.

    Now, the sensors don't detect bicycles. (i've tested it on different occasions). For the sake of argument, which is my best (and most legal) course of action? (I already just go through the red light) In the event of a cop stopping me (I'm kinda out in the sticks) for going through a red light, I'm looking for a good argument I could give:

    a. stop and wait for a car to come along in the same direction to trip the circuit (however long that may be)
    b. go over and push the pedestrian button to activate
    c. go through the red light
    d. something else - what?

    I

  2. #2
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    I normally use method a). There are plenty of cars at rush hour, when I ride, and it takes about a second for one to show up.

    There is an automatic door in my garage at work. It will trigger if I lay the bike down on the pickup area. That might be quicker than going to the pedestrian button, which I also sometimes do.

    Paul

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    I'd use the button, most light sensors on the road are weight sensitive like many left turn lanes, you can see the trigger outlined by tar.

  4. #4
    Ride the Road Daily Commute's Avatar
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    I treat lights that don't trigger for me as stop signs. Better positioning of your bike could help trigger the sensors. Check out this thread. It includes diagrams.

    P.S. Most sensors detect metal, not weight.

  5. #5
    cab horn
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    Run it. No amount of posturing your bicycle triggers the lights around here.

    Of course let me add the disclaimer that you only do so when there are no cars around, obviously.

  6. #6
    Desert tortise lsits's Avatar
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    Quote Originally Posted by glowingrod
    I'd use the button, most light sensors on the road are weight sensitive like many left turn lanes, you can see the trigger outlined by tar.
    Most sensors are inductive sensors. They sense changes in an electrical field. I find that if I stop with my chain ring on the perimeter, I can trip about 90% of the sensors. For the others, I hit the pedestrian button.
    Wish I didn't know now what I didn't know then. - Bob Seger

  7. #7
    Just riding andygates's Avatar
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    Write to whoever is responsible for the lights - local Council or whoever - and point out that the sensors don't detect bikes. The sensitivity of these things is adjustable to a degree. Oh, unless you ride carbon!

    Meanwhile I'd wait for a car if it was an ordinarily busy road, but if it was quiet, I'd treat it as a "Stop" sign: stop (or go very slow) and check the crossing road for traffic, then run it.

  8. #8
    By-Tor...or the Snow Dog? hi565's Avatar
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    Use the button, or just run the red light
    ----------------------------------------------------------

  9. #9
    Ride the Road Daily Commute's Avatar
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    Quote Originally Posted by operator
    Run it. No amount of posturing your bicycle triggers the lights around here.

    Of course let me add the disclaimer that you only do so when there are no cars around, obviously.
    You may be right. I thought the same thing, until I started putting my bike on the lines centered top to bottom (see the link from my post above for diagrams). I can trip a lot more signals than I used to be able to. Before complaining to city government, try following the diagrams.

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    Just an idea, I came across this while shopping for motorcycle accesories. The installations instructions say a flat surface is needed, but I'm thinking that since it's 5/32 of an inch wide and 2 inches long it could go across the bottom bracket just fine.

    http://bellsouthpwp.net/e/z/ezbrake/signalsorcerer.htm

    Here's the official site. Who wants to be the guinea pig and tell us if this thing actually works?
    http://www.signalsorcerer.com

  11. #11
    Senior Member TuckertonRR's Avatar
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    Thanks for the replies! Later today I'll try out various positions of the bike; & see how that works.

  12. #12
    Philly bike nerd nocoins's Avatar
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    Quote Originally Posted by TuckertonRR
    Ok, there's this light near where I live which is automatically on "red" for both directions. Both directions operate via a sensor (either on top of the light/in the road??) when a car comes upon the light it changes to green for about 10 seconds, then cycles to amber,then red. It does this for all four directions at a standard 4way intersection. This also has buttons pedestrians can push to activate it as well.

    Now, the sensors don't detect bicycles. (i've tested it on different occasions). For the sake of argument, which is my best (and most legal) course of action? (I already just go through the red light) In the event of a cop stopping me (I'm kinda out in the sticks) for going through a red light, I'm looking for a good argument I could give:

    a. stop and wait for a car to come along in the same direction to trip the circuit (however long that may be)
    b. go over and push the pedestrian button to activate
    c. go through the red light
    d. something else - what?

    I

    blow through the light. Its for novelty purposes only.... just like stop signs with white borders. hahahah

    but seriously, just go through it.
    bike bike bike bike bike bike bike bike bike

  13. #13
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    It's an outrage what cities and the burbs are doing to their streets. I find this attitude particular harmful in cities where these sensors allow cars to reach speeds exceeding 40 mph on regular streets.

    In my town, all of our side streets that lead to the main boulevard are activated by sensors. As a result, the pedestrians have to run across that boulevard because it changes so fast! At night when there's very little traffic, these lights change every five minutes.

    I treat these lights at night like a hard stop sign. In fact, I'll get close to the crosswalk and when all the cars are gone, I'll cross and run the light.

  14. #14
    Al noisebeam's Avatar
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    I commute on side streets that cross a dozen or so main streets. Lights are activated by inductive sensors and by 'bike crossing' buttons that have been installed at side of road.

    The only solution I have is to either wait for a car or press the 'bike crossing' button. But pressing the button is a real pain as the roads I am on are three lanes (left, straight and right) and I am either going straight or left so I need to cross between all the right turning cars (who don't have inductive sensor). Note there are no straight going cars as this is not a typical traffic flow (no one leaves neighborhood to cross into another neighborhood, except school bus and post man)

    What I always do is ride up to cross button and press it then wheel bike over to straight or left turn lane, unless I see a car coming or one already over sensor then I go direct to position.

    1. Because of 'bike crossing' button city has no reason to tune inductive sensors for bikes.
    2. Cross traffic is much too fast and dense to cross without green light
    3. Cars turning right may trigger inductive sensor, but as soon as they get off sensor it untriggers. So even in rare cases I can get bike to trigger as soon as a right turn car goes a little to far to the left it untriggers. Also there is no indication that by bike has triggered sensor as it still may take a few minutes for lights to switch after trigger.

    So I am stuck using these 'bike crossing' buttons (and in a few cases crosswalk buttons) which make my life more complicated and dangerous as I need to cross moving traffic.

    Al

  15. #15
    feros ferio John E's Avatar
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    1) Learn how to trigger traffic lights as effectively as possible.
    2) When you encounter a nonresponsive signal, report it to the relevant authority, such as the city Traffic Engineer. In my own city, I have had success about 50% of the time with my complaints.
    3) If you are certain that a light is not responding to you, treat it as a malfunctioning signal and (legally) proceed with caution, as though you were at a stop sign.
    4) Be persistent and vocal. It is quite reasonable to demand that traffic signals respond to all legal road users. The technology exists, and it is not particularly expensive.
    "Early to bed, early to rise. Work like hell, and advertise." -- George Stahlman
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  16. #16
    genec genec's Avatar
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    Quote Originally Posted by lsits
    Most sensors are inductive sensors. They sense changes in an electrical field. I find that if I stop with my chain ring on the perimeter, I can trip about 90% of the sensors. For the others, I hit the pedestrian button.
    With the inductive sensors it would seem that a well placed magnet might make a difference.

    I have tried this, putting a very strong rare earth magnet on the bottom of my BB, but I have yet been able to trigger a light.

    I suppose taping it to a spoke to get it closer might be a solution....

    Just seems like there ought to be a way to beat these lights.

  17. #17
    Senior Member sggoodri's Avatar
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    Quote Originally Posted by genec
    With the inductive sensors it would seem that a well placed magnet might make a difference.

    I have tried this, putting a very strong rare earth magnet on the bottom of my BB, but I have yet been able to trigger a light.

    I suppose taping it to a spoke to get it closer might be a solution....

    Just seems like there ought to be a way to beat these lights.
    A permanent (DC) magnet will make no difference. You need to raise the resonant AC frequency of the sensor loop circuit by reducing the effective inductance of the sensor loop. This happens when the AC magnetic field induces currents in a conductor such as a metal car or an aluminum bicycle rim.

    See my articles at
    http://humantransport.org/bicycledri...nals/green.htm
    and
    http://humantransport.org/bicycledri.../detection.htm

    Sometimes the bike just isn't big enough to trip an insensitive detector circuit's change threshold, but these articles will tell you how to maximize your impact on the circuit.

    -Steve Goodridge

  18. #18
    Member coldcanuck's Avatar
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    Can't speak for everywhere, but in Ottawa (and I believe other parts of Ontario), there are three yellow dots on the lane(s) at intersections to show you were to position your bike for maximum sensitivity to trip the signal (I think this was originally for mororcycles, but they use it for bike path/road intersections now as well). If there is an exclusive left turn lane for a protected left turn arrow, there will usually be dots there as well. 99 times out of 100, you will see the "walk" signal for opposing traffic switch to the flashing don't walk as soon as you park your bike on the dots.

    For folks in places where there aren't dots, you'll sometimes see cuts in the road just before the thick white stop bar (It sort of looks like someone took a saw and made narrow side by side longitudinal cut in the road right where a car's wheels would go, then filled the them with tar... I hope this makes sense!). Generally, right on top of these cuts is the most sensitive point for the detector. If you park on top of those cuts, you'll almost always trip the lights.

    Try that, and if it doesn't work, call the City... Especially if it's a new or recently reconstructed intersection. I've heard of contractors putting detectors for left turn lanes in through lanes and vice versa...

  19. #19
    Al noisebeam's Avatar
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    Quote Originally Posted by John E
    1) Learn how to trigger traffic lights as effectively as possible.
    2) When you encounter a nonresponsive signal, report it to the relevant authority, such as the city Traffic Engineer. In my own city, I have had success about 50% of the time with my complaints.
    3) If you are certain that a light is not responding to you, treat it as a malfunctioning signal and (legally) proceed with caution, as though you were at a stop sign.
    4) Be persistent and vocal. It is quite reasonable to demand that traffic signals respond to all legal road users. The technology exists, and it is not particularly expensive.
    Problems:
    1) The best general techniques of where to align bike to sensor can be learned and do help, but the fact that there is not instant feedback of a trigger (It still can take several minutes for lights to change after a trigger) it is hard to learn what works best unless one has lots of patience. Around here they actually un-trigger if the vehicle moves away - this is so right turners on red who trigger the sensor don't do so unneccesarily. But I have found left turns and straights that untrigger as well*. The final and most complicating factor is that on the roads on my commute the city is chip sealing the roads and there is no longrer a visible indication of where sensors are. (previously there were cut marks covered in tar)

    2) I have twice been told to use cross walk if triggers don't work. Also on many of the intersections there is also a bike 'friendly' post on sidewalk with push buttons that say 'press for bike crossing' or some such nonesense, so sensors are not required to work for bikes. However these buttons require me to sometimes cross two lanes of vehicles (I find myself playing frogger, or more often pressing button then making a big u-turn around back of line of straight going cars to get into left turning lane)

    3) Impossible at rush hour on the 14 intersections I cross on my daily commute. I ride on side streets and cross main 7 lane roads - there is never a safe opening in traffic to cross.

    4) True - I should stop complaining and talk to the right people. But these 'bike crossing' buttons are an easy out for the city.

    What I don't understand is why can't these be set to be ultra sensitive? What is the worry traffic engineers have? That something that is not a vehicle will trigger, like a baby carriage on the adjacent crosswalk????

    Al

  20. #20
    feros ferio John E's Avatar
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    Quote Originally Posted by noisebeam
    ... What I don't understand is why can't these be set to be ultra sensitive? What is the worry traffic engineers have? That something that is not a vehicle will trigger, like a baby carriage on the adjacent crosswalk?
    The main limitation is that an ultrasensitive loop might respond to a car or truck in the adjacent lane, triggering a left arrow when there is no left-turning traffic, for example. In practice, the quadrupole loops can generally be sensitized to bicycles, and many cities are discovering the benefits of modern video-based sensing systems, which can respond reliably to bicyclists, pedestrians, and motorists.
    "Early to bed, early to rise. Work like hell, and advertise." -- George Stahlman
    Capo [dschaw'-poe]: 1959 Modell Campagnolo, S/N 40324; 1960 Sieger, S/N 42624
    Peugeot: 1970 UO-8, S/N 0010468
    Bianchi: 1981 Campione d'Italia, S/N 1.M9914
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  21. #21
    Get outdoors! :) Becca's Avatar
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    Quote Originally Posted by Anthony King
    Just an idea, I came across this while shopping for motorcycle accesories. The installations instructions say a flat surface is needed, but I'm thinking that since it's 5/32 of an inch wide and 2 inches long it could go across the bottom bracket just fine.

    http://bellsouthpwp.net/e/z/ezbrake/signalsorcerer.htm

    Here's the official site. Who wants to be the guinea pig and tell us if this thing actually works?
    http://www.signalsorcerer.com
    Next payday I'm ordering one of these. According to the site, the Signal Sorcerer(TM) plays with the inductive loop, causing the traffic signal to cycle. Supposedly it works for bicycles as well as motorcycles!
    ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~
    Enough of fostering fear.
    Enough of the illegitimate war.
    Enough of the hate.
    Enough is enough: vote Democrat!

  22. #22
    Senior Member
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    Find out what the local motor vehicle code says about traffic signals that are broken or not functioning. With respect to you this signal is broken and you know it without waiting a long time, which may be required by your law. However you know it is broken so you may have no problem.

  23. #23
    Perineal Pressurized dobber's Avatar
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    Quote Originally Posted by Becca
    Next payday I'm ordering one of these. According to the site, the Signal Sorcerer(TM) plays with the inductive loop, causing the traffic signal to cycle. Supposedly it works for bicycles as well as motorcycles!
    Send me your money. I'll send you back a hunk of metal and I'll even include a bent up piece of sheet metal to help the fuel mileage of your auto.

  24. #24
    Senior Member sggoodri's Avatar
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    Quote Originally Posted by Anthony King
    Just an idea, I came across this while shopping for motorcycle accesories. The installations instructions say a flat surface is needed, but I'm thinking that since it's 5/32 of an inch wide and 2 inches long it could go across the bottom bracket just fine.

    http://bellsouthpwp.net/e/z/ezbrake/signalsorcerer.htm

    Here's the official site. Who wants to be the guinea pig and tell us if this thing actually works?
    http://www.signalsorcerer.com
    From the SignalScorer site:

    The vast majority of traffic signal controllers in the U.S. are connected to inductive loops that are embedded in roads. Concentrations of iron increase the inductance of the loops; the increase in inductance trips the traffic signal.
    This is just plain wrong. Modern signal detectors sense a *drop* in inductance caused by a vehicle, not an increase. The inductance drops because the high frequency current used in the loop circuit causes eddy currents in the conductive material of the vehicle over the loop, and these eddy currents generate their own magnetic field in opposition to the loop field. Since the resulting magnetic field over the loop is less strong as a function of its loop current, the effective inductance is less. The resonant frequency of the circuit increases slightly as a result, and the increased frequency is classified as a vehicle detection.

    Inserting iron into the center of a coil can indeed increase its inductance, but only if the eddy currents are limited, either because the circuit frequency is low (e.g. 60 Hz) or the conductivity of the iron is kept very low (e.g. a ferrite core made of powdered iron). With traffic signals, the signal frequency is high (well over 20 KHz) and the metal conductivity is very high. This causes the eddy current effect to overwhelm the ferromagnetic effect.

    -Steve Goodridge, Ph.D. Electrical Engineering

  25. #25
    Al noisebeam's Avatar
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    Quote Originally Posted by John E
    The main limitation is that an ultrasensitive loop might respond to a car or truck in the adjacent lane, triggering a left arrow when there is no left-turning traffic, for example. In practice, the quadrupole loops can generally be sensitized to bicycles, and many cities are discovering the benefits of modern video-based sensing systems, which can respond reliably to bicyclists, pedestrians, and motorists.
    I see. In my specific case all the intersections I use do not have a protected left so the inductive sensor in the left turn and straight do the same thing. The right turn lanes don't have one, so a right turner could trigger the sensor, but that would be a good thing as anyone sitting there that long may need a signal for right turn (also when these sensors are un-set by removing car it resets the light cycle and the light doesn't change) So the city could turn up the sensitivity to max on these three intersections without ill effect, but they probably use a standard instead of setting per specific case.

    I just find it terribly annoying and somewhat dangerous to wheel my bike across the straight and right turn lane and press the x-walk button when I want to make a left - sometimes I walk the other way but was nearly clipped by a left turner. All the cars are piled up in the right turn lane and moving forward slowly so I need to make hand signals to go between them both ways. Rarely do any cars go straight or left so I can't rely on them to trigger signal.

    Al

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