Traffic light magnetic gizmos

[montmil]

The following two items are from the 06 JAN 2013 Airheads Digest regarding the viability of the so-called traffic light triggers, etc -those heavy chunks of iron that get bolted beneath some owners motorcycles.

Opinions expressed are those of the authors. I really like Tom Cutter's view.

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Date: Sat, 5 Jan 2013 23:40:40 -0800 (PST)
From: Doug <sewerman_98@yahoo.com>
Subject: Re: Traffic Light magnetic gizmos?

If anyone is interested the vehicle detector that triggers the traffic signal is a couple of loops of wire that is embedded in the pavement either in a saw cut slot that is sealed with epoxy or an encapsulated coil that is paved over. The loop can be a rectangle, circle, zigzag or figure eight. The loops of wire act the same way a metal detector does; a current is passed through the loop setting up a magnetic field and the metallic mass of a vehicle disturbs that field and triggers the traffic signal controller. A motorcycle stopped in the wrong spot won't be detected by the system. The little painted motorcycle symbol is directly above where the wire is in the roadbed where it is most sensitive. Sometimes you can see the outline of the loop and stop on top of the wire which will trip the light.

The magnetic gizmos that you stick on the bottom of your bike are supposed to project a magnetic field that interacts with the vehicle sensor loop acting like a mass amplifier. I would think that you would have to use a very strong magnet for it to have any effect.?
The sensitivity of the loop is adjustable by the traffic signal maintenance people so writing letters or otherwise complaining might get some action.

I know all this due to the fact that I have installed these things for many years.

Doug  Sonoma CA ABC #7764 1992 R100R 2000 R1100RT

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Date: Sun, 6 Jan 2013 03:04:40 -0500 (EST)
From: Tom Cutter <tpcutter2@aol.com>
Subject: Re: Traffic Light magnetic gizmos?

The traffic light magnets work perfectly for their intended purpose: [size=12]To separate impatient BMW riders from their money.[/size]

If a magnetic field would work to trip the signal, why won't the powerful field around the alternator do the job? Becaue that isn't how it works. It is a mass sensing system, and the low mass of a motorcycle doesn't work.

If you have a slow or insensitive light near you , then write letters to the Township or municipality Department of Transportation.

Tom Cutter Yardley PA www.RubberChickenRacingGarage.com

[Bob_Roller]

I had a problem with the traffic light at the expressway exit I normally get off on with the commute home .

Getting home at 'normal' hours, there was no trouble with other vehicles pulling up to, or already sitting at the light, to get the light turn green .

But with my working late, sometimes, it would be 15 minutes before another vehicle may exit here .

I sent an email to the Arizona Department of Transportation (ADOT),
I received an email from ADOT about 5 days later, that a maintenance crew would be working on this intersection within the next 2 weeks and they would adjust the sensitivity of the controls at that time .

I was told to send another email, if it still wasn't sensitive enough .

Within 2 weeks, the sensor system worked for me .

That was 2 years ago and it still works as of early this morning when I got home at 0100 .

[nhmaf]

Well, it is the mass/amount of ferro-magnetic material within the loop which perturbs the current signal and trips the light, but motorcycles (especially newer ones) often don't have enough of this material to trip the sensors unless they are adjusted to be quite sensitive.

On some occasions, I have been able to get a reluctant sensor to trip by stopping my bike right over/just inside the slot where the wire is buried, and extending my sidestand so it is contacting the epoxied-in area of the slot.   But, it has also failed to work at least as often as it has seemed tohelp.   So, the best thing to do is to write the local DOT if it is someplace where you ride alot.   For those - just passing through- sorts of situations in a strange town, well, you can try this approach, and if it still doesn't work, wait for a car to come, or be sure that no one is coming and go through, after waiting a more than sufficient time for it to otherwise trip for you.

I did buy one of those magnet thingies to try years ago - it was basically a "cow magnet".  I found that it didn't have any noticeable affect on the traffic signals in my area as far as getting some to trip that otherwise wouldn't with just my motorcycle on the sensor grid.

[Bob_Roller]

I just remembered a trick that worked for me on some not so often visited intersections, get the bike on one of the cuts in the pavement, then push the center stand down to contact the pavement .

You may have to leave it there for a minute or so for it to trip the sensor circuit, if the intersection has pedestrian crosswalk warning signs, if the sign for the crosswalk you are at, starts flashing the red hand, chances are good that you have tripped the sensor circuit .

[k_enn]

If you cannot get the sensor to trip, go through, and end up being issued a ticket (either camera light, or hidden officer), check you state's traffic laws.  In some states a defense to a red-light ticket is that the traffic light was malfunctioning.  There have been some reported instances where a motorcyclist successfully prevailed on this defense when a sensor light failed to activate and asserted that the light malfunctioned because it was not tripped by the motorcycle.