Introduction: Trigger GREEN Traffic Lights

Picture of Trigger GREEN Traffic Lights
if you or someone you know, owns a motorcycle, a scooter or even a small car, you've probably noticed that it's easy to get stuck at traffic lights. Well, I'm going to explain why it happens and show you a great little trick that will save time, gas and frustration by getting you a green light every time.

Step 1: The Problem...

Picture of The Problem...

At most traffic lights and turn signals, you will notice a loop of wire buried in the pavement of the road near the stop line. This is called an Inductive-loop traffic detector that operates by sensing a change in frequency to the electromagnetic field over the coil of wire. In other words, when a car pulls up, it senses the vehicle and the light changes. Most motorcycles, scooters, bicycles and small cars don't have enough conductive material to trigger these loops and change the traffic light.

Step 2: The Solution...

Picture of The Solution...

Produce a very powerful field that increases the inductance in these traffic sensors, and causes the light to change! Here's how to do it...

Step 3: What You Need!

Picture of What You Need!

2 Neodymium magnets. I chose two from CMS Magnetics that have a pulling force of over 6lbs each. I also bought a roll of heavy duty exterior mounting tape.

Step 4: Attach It...

Picture of Attach It...

After cutting off a small strip of tape, I attached it the magnets. Then I applied it to the bottom of our test scooter, perpendicular to the road.

Step 5: Optional Step & Video

Picture of Optional Step & Video
Because magnets rust, I put them stacked together inside a waterproof, rust-proof, pill holder or Bison Tube and then stuck this to the bottom of the scooter. Should last a long, long time! Now here is the video!

You can learn more about how this works Here


MillennialDIYer (author)2017-11-15

10 years later and the induction loops are still a PITA for riders everywhere.

Green_L (author)2017-03-02

There is another solution which really works.

I developed the active electronic device coupled with loop
antenna. The device receives the signal, measures it, and transmits a specially
generated signal back to the induction loop. As a result, the sensor thinks
that a large vehicle is passing above.

It works with all induction loop sensors conforming NEMA
standards, in the frequency range of 10 to 200 kHz.

I sell the devices on eBay:

millscha (author)Green_L2017-09-13

The loop pictured is called a Quadrapole loop. It is most detectable over the very center wire. Pull your bike over the center wire it should detect you.

Thanks, Charles

ChrisR20 (author)2016-10-25

If you are at a red light and no one else is there waiting at the intersection and lets say you wait there like this for about 5 minutes. Do you run the red? If it was red for 15 minutes would you really sit there for that long with no one around? what about 1/2hr or 1hr?

JeremiahS15 (author)2016-03-17

This is nonsense. Induction loop systems are triggered by eddy currents created by a resistive change in magnetic flux.
For starters, the magnetic field created by the alternating current within the coil has no effect on the polarity of a permanent magnet. Meaning that magnet will have no more effect on the magnetic field produced by the primary coil than any other piece of equally conductive material of the same size, which when compared to the size of your bike, is practically nonexistent.
In reality, when a large piece of conductive material passes over the field, the induced current creates a new field that disrupts the current of the initial loop.
It's that *change* that triggers the computer into knowing you exist. In the same way, a car parked over a sensor does nothing. Entering and exiting the perimiter of the loop triggers the sensor.

A tiny magnet will not have any effect, and any small effect would not be due to it's own magnetism.
Try laying the bike down toward the sensor.

JoeM182 (author)JeremiahS152016-04-05

There's no question that a permanent magnet will create a *different* induced current in the induction loop than that produced by induced eddy currents in the conductive material of a large vehicle, but it certainly isn't nonsense. As your scooter, bolstered by permanent magnets, drives over the induction coil, the coil *will* see a changing magnetic flux which induces a current. When your scooter stops, the induced current will also stop. That should make your scooter look pretty much like any other vehicle that enters the loop and then comes to a stop (unless the tripper is designed to look for the continued presence of a stopped vehicle through the use of alternating current - I don't know if any are programmed that way). I suspect this idea would work for pretty much any traffic light, because they can't be programmed to be terribly sensitive to any particular signature - different vehicles will all create slightly different induced current signatures.

bhermance (author)2015-07-07

I don't think we have these here in Michigan except in a few places. I thought they were timed throughout the day as to rush hour traffic,etc. I thought the traffic cams people take care of traffic control. duh is me. I never even heard of this metal detection things in the roads. News to me!

Ludwig Von Mech (author)2011-05-22

In Wisconsin this is no longer a problem, as in 2010 we got a new law that allows bikes to wait and proceed through the red if traffic allows. I used to report all the lights that did not work, but now I don't bother. I just ride through.

awesome i let a car get in front of me lol

bhermance (author)2 stroke 2015-07-07

yep thats a good way to get through LOL

pbleier (author)Ludwig Von Mech2013-09-18

Does the rule apply to my SMART car or scooters? If so, maybe we'll move to WI.
Sometimes we just get kind'a P.O'd and run the dang thing. Anytime the authorities stop you - whether you're handcuffed and put in the back of the police car or not, it's considered an "arrest." So I feel the light has arrested me without cause. Never tested this in a court, but that's my story and I'm stickin' to it. ;)

Ludwig Von Mech (author)pbleier2013-09-19

Just to Bicycles, scooters, motorcycles, and other similar traffic. A solution is to wait at least 1 minute, and then go if you are clear. Problem with "45 second" laws is that if the roadway is really busy, it does not matter; you still cannot get across a flowing river of steel.

pcooper2 (author)Ludwig Von Mech2012-05-06

I've been treating signals with unresponsive road sensors as four-way stops for decades, even without the benefit of such a law. If I hadn't, I'd have died of thirst and starvation while waiting for the light to change ages ago!

We have that here, too. But sadly, it doesn't apply much for heavy traffic when you have a line of cars behind you getting madder with each missed cycle and no opening to go. This is a helpful fix.

You have a very good point.

Another way to fix this situation is to become proactive; the inductive coils in the road will not trigger if they are out of adjustment. I have reported these for years and years, and I have also seen them become so bad that a pickup truck will not work. The state supervisor is on my email list, and he will send out a crew if someone complains. They do not have time or manpower to continually inspect each light.
I will try this magnetic solution at a place that I know does not work.

Also, if you are on a bicycle or moped, do not hug the curb. You will get old waiting for the change. Ride over the lines slowly, and position yourself directly on top of the transverse wire. If it is still working, you will trip it.

Happy riding.

pcooper2 (author)2014-08-27

This trick from Kipkay on YouTube DOES NOT WORK. I proved it by securing a powerful rare-earth magnet from a disk drive to the end of a 8-foot piece of PVC pipe and waving it over the inductive detection loop at an intersection with infrequent traffic. Nothing happened. The only thing that triggers the light to change is a large, ferrous object, like an automobile.

bdepalma (author)pcooper22015-04-23

Well you really can't say Kip's trick doesn't work because you didn't / couldn't follow his simple directions. You did your own thing which didn't work. I did follow the directions, it worked for me first time every time. Kip's directions were very simple and very simply written. And I'm not even a rocket scientist dammit!

Thanks Kip for a very cool and practical hack of life

myr1 (author)2014-10-14

This actually does work, I would just recommend a larger Neo magnet. They are pretty cheap on ebay now days.

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hello_3824 (author)2014-03-14


cathys (author)2010-08-08

First thing...if you have a scooter you should ride on the side of the road with bicycles instead of putt putting along where people in cars, trucks and motorcycles travel. Second thing...if you took a motorcycle course or did some research you would find out that the lines underground can sense metal. So, if you are on a little scooter or even a motorcycle there is not enough metal for it it sense that's why you will see a motorcycle at a line moving their bike back and forth over the line and Third thing....really? really? You can't wait one minute for a light? dah

Furball_Fidelis (author)cathys2010-08-08

Yes..scooters are entitled to ride on the road just like any other road legal motorized vehicle...and most of them are able to keep up with traffic however scooters are not meant for highways where the speed limit is 65Mph or 100Kmph (not 100% on the conversion) and yes...I own a motorcycle and it's only a small one a 250 Suzuki..and at most intersections i'm able to trigger the light...but there's very rare times when I have to move my bike around to trigger them

pbleier (author)Furball_Fidelis2013-09-18

My 400cc Yamaha "scooter" may not beat your bike off the line, but I'll pass you up on those long, desert straight-aways and wonder if you could keep up...

Furball_Fidelis (author)pbleier2013-09-18

Maybe. Have fun battling the wind though. and I"ll pass you again when you run out of gas.

P.S.Scooters aren't meant for long distance. Motorcycles are.

P.P.S. you really suck at trolling.

pbleier (author)Furball_Fidelis2013-09-18

I get 50+ mph even at top speed, so that puts me filling up at about every 200 miles. Yeah, scooters aren't "meant" for long distance - either are 250cc bikes, but that doesn't mean you can't have a great, fun ride. You're right about the wind - it was a b*tch comin' back when the headwind changed from coming from the right to the left, but with 30,000 miles on the bike I managed it without incident.
"Trolling?" Not exactly sure what that means - I was just looking for a way, or a device, to help the dang intersection loops realize I'm sittin' here waiting for the light to change in my favor. People say "magnets" but others say that doesn't work. Somebody should come up with a device that'd insure bikes and small cars get noticed by the technology. They'd make a bundle. Our SUV - no problem... our SMART, often gets ignored by the inductive loop.
I just get p*ssed when scooters get dissed and told to stay on the "side of the road." We haul azz - and run with the best of 'em. My son-in-law's 650cc is no match for my scoot.

pbleier (author)cathys2013-09-18

My scooter does over a hundred mph with two people on board - don't ask me how I know this is fact, but on a ride from LA to Laughlin if you don't do at least 90, the big trucks will ride up behind you and blow you off the road. It's 400cc strapped to (mostly) a bunch of plastic, so I'm looking for a device to help trigger the lights. Same problem with our SMART car - it's got a plastic skin. (Don't hate me 'cause I'm getting two or three times your mileage...)

ChristoferWeber (author)cathys2013-07-01

First thing... It probably depends on where and what state/country,but where I come from, scooters should keep to the road.
Second thing... If you did more research you would find that those inductive-loops have a problem detecting anything else but cars.
But as someone working with these things, I'm going to say this: This is not something you should have to handle. There is a simple solution to this problem, and that's a thinner, diagonal loop across the street. These diagonal loops, or "wings" as we call them, can even detect bicycles, and are used to detect just that.

snuzzle (author)cathys2012-05-28

First, yes a bicycle or slow scooter should be on the side of the road... unless there is a right-turn lane, in which case he or she should be in the through lane so as not to get right-hooked by a car making a right turn :) I'm not going to get right-hooked. If I'm going straight, I'm in the through lane. If I'm turning left, I'm biking to the left. You know? Common sense here.

Thirdly, it's not a matter of waiting... some lights do not change at all unless they detect a vehicle. The magnets allow them to detect that a bike or small scooter is there so they know they need to change.

cowen (author)cathys2010-08-08

One of my customers has a 80 model Harley and had the magnet idea professionally installed some years ago because of the loops not picking up very well. The loops are burried in cement so the only way to FIX them is to dig up the payvement. The only way to check them for PROPER operation is to trigger them. If the cement shifts in the heat and cold that can break the loop and thus you need something to help trigger them. The Loop starts most lights counters that change them to green it is not a Green light EMS device that makes your side change and everyone else RED. I work on LOOPS at the drive thru and sometimes we have to cut them out and replace them or fix the junctions that connect to the inside equipment.

anjin12 (author)cathys2010-08-08

Cathys --- First things first. Scooters ARE entitled to be on the road, they are a "motorized" vehicle, and, as such, shall NOT travel in the bicycle lane if marked. Second, most states and provinces require that "bicycles" travel "As far to the right as practicable", not as far as possible and recommend that a path 1 metre or 3 feet be maintained from the edge of the road. .... Now ... for the rest of your comment ... Most bicycles have enough ferrous material in the crank set (pedals) to activate the sensors embedded in the road. The bicycle must be on the outside edge of the circle to "change" the current to activate the lights. For more information see ... ... Thanks and have a good day

cathys (author)anjin122010-08-08

putt putt

eskate (author)2013-08-25

stronger the magnet the more possibilities to change to green?

rmelchiori (author)2010-08-10

I think that the idea the author is talking about has been misunderstood. The problem isn't trying to get a red light to turn green so he doesn't have to wait. Many intersections have sensors at them so that the light never changes unless it senses a vehicle. This is done to promote better traffic flow. Same thing for left turn lanes. I know that this technique works. There is actually a product sold to do this. Nothing more than a magnet mounted under the motorcycle. Not even a rare earth magnet. I bought one for my motorcycle and it worked well.

lucek (author)rmelchiori2010-08-22

Except you aren't doing it in a blinded fashion. Review the evidence: !:Prior probability, low as this is based off a misconception on how the censors work. 2:All test that confirm the effectiveness aren't well controlled and can be just the rain-maker fallacy. 3:One test show the lack of effect. Thees 3 factors would suggest that it doesn't work.

rmelchiori (author)lucek2010-08-22

Dude, Check this site out. This is only one that I found that are selling this. I actually used it and can tell you it works. If you don't want to believe it, that's up to you.

finton (author)rmelchiori2013-01-02

That link just gets a "404 (Page Not Found) Error" now...

rmelchiori (author)finton2013-01-02

Do a Google search for 'motorcycle green light trigger' and you'll find a bunch of different types. There is also a bunch on

lucek (author)rmelchiori2010-08-22

I just explained how you are most likely mistaken and you counter my argument by sending me to a site that has a major bias to claiming it works (IE they're selling it). Do you see the problem here? Restating the points, the magnetic field is too weak to effect the censor in any major way. The censers measure inductance not magnetic fields so non-ferromagnetic metallic materials will trip the censer. The only proof you've cited is anecdotal in nature and can fall under confirmation bias AKA the rainmaker fallacy. Finally bguiles recounts an experiment that negates the premise of thees devices. What are we left to think? The most likely conclusion is that thees don't work.

Wesfletch (author)lucek2011-04-12

He literally said, HE used it and it worked. It doesnt matter if the site has a bias, he doesnt. And, why does it even matter, you're here, complaining about someone ELSES work, saying its B.S. But, have you tested it? Theory is all well and good, but hard fact is necessary to even attempt a semi-accurate educated guess. I think, before you try to disprove someones hard work, you actually have the decency to take the time to back it up.

lucek (author)Wesfletch2011-04-12

look up the rainmaker fallacy would you.

janettetsmith (author)lucek2010-08-24

@lucek: It sounds as like you are calling @rmelchiori a liar. Hmm. Well then, if you can do that you are without a doubt an expert on this topic.

lucek (author)janettetsmith2010-08-24

No I specifically stated I didn't think he was a liar. The rain maker fallacy is a kind of self deception. it is very easy to trick oneself and the nature of this case appears to be such. Now I'm not an expert on the topic but what knowledge I have from my 200 level courses I've taken, research and reading from others says that this is wrong. Finally before accusing someone of slander check to see if you are in fact mistaken.

janettetsmith (author)lucek2010-08-24

@lucek: Slander is verbal, you probably meant libel, that’s the one where you write it.

lucek (author)janettetsmith2010-08-24

Pedantic is both.

janettetsmith (author)lucek2010-08-24

@lucek: Your attempt to turn the attention on someone that pointed out your mistake by referring to them as nit picky is predictable. However, now you are up to two words used incorrectly. Anyone that can read can see you used the wrong word. They don’t have to be on the head of a pin to do it. You’re a bully. I’ll bet you love the Internet.

lucek (author)janettetsmith2010-08-24

Um. pot, kettle, black much? Do you have a point beyond trolling?

randomray (author)lucek2010-09-30

Apparently you don't ride a bike , as many cyclists know they can tape a magnet to the bottom bracket of thier bicycle so the coils in the road will pick them up . Yes , this does work whatever the reason .Empirical data trumps theory every time . And lucek why are you trolling ?

kinetic_elite (author)lucek2010-08-24

Give this guy a break. Maybe he doesn't spend all day thinking about sensors! Why start a flame war?

Lee Wilkerson (author)lucek2010-09-09

These triggers work on the same principal as passive theft detection in stores: An oscillator is running with a very large coil. In the case of the car sensor, the coil is under the road. When something with enough metal bulk is over the sensor, it shunts the coil and changes the frequency of the oscillator.
It is the same principal as:
All you need is for the magnet to be in close proximity to the sensor.
In the photos, the trigger type is a narrow loop. Those usually sense motorcycles anyway. It's the wide loop ones which don't. Almost none of them will sense a bicycle, so if you can make a bicycle trigger one, then you've got it.

lucek (author)Lee Wilkerson2010-09-09

The test I would propose it to have a wooden object at a objectively verifiable trigger (there was an example were the coil operated a gate) and install a magnet on it. Isolate the variables.

JMRaphael (author)lucek2010-09-27

If I understand the video correctly, the author is demonstrating at a light that will change if and only if the sensor is triggered. If the magnet didn't work, then the light wouldn't change at all. That, effectively, is your blind. The control situation is what he shows first: a motorcyclist at the light that will not change for him. The experimental situation is the motorcyclist at the light with the magnet attached. Since the light changes, the magnet must work.
From a theoretical perspective as well, this should work. If you look at an inductor, a simple metal core (what you get with a steel-frame car) changes the inductance a little bit. Since most bikes, scooters, etc lack sufficient metal to significantly change the inductance, magnets are added. This works because magnets have a much greater effect, based on the strength of the field they create. Such strong magnets alter the inductance sufficiently to trigger the sensor.

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