Controlling Traffic Lights

Here's a couple of YouTube videos on the subject of controlling traffic lights. The first video is for pedestrians. It claims that by clicking the walk button in a special way you can cause the traffic light to change in your favor. This secret code is: 3 short clicks, 2 long, 1 short, 2 long, and 3 short. Sounds like total baloney to me. Of course, if you live in New York City, many of the walk buttons have no effect whatsoever on the signal because they were disconnected decades ago.

This second video claims that it's possible to cause red lights to turn green by using a universal remote control. I'm more inclined to believe this is possible, since I know that emergency vehicles do have devices to change the lights to green. However, you would first have to locate the correct frequency, which would mean standing there with the remote on scan mode until it hits on the right one. Also, you'd need to know the correct code. (The video claims the code is 911.) Finally, would a typical remote control have a strong enough signal? Oh, and it would also be completely illegal.


Posted on Mon Apr 16, 2007


The click thing in morse code spells SMEMS. As a hoax it would have been a lot funnier if it spelled something.
Posted by Razela  on  Mon Apr 16, 2007  at  02:14 PM
Ok, so there may be some way to remotely change a traffic light ... but how likely is it that the designers of the system would use a device most people have at home ... and risk the traffic signals going crazy every time somebody watching TV nearby hits the remote?

As a birthday card I once received says, "I've learned that a Universal Remote Control does not, in fact, allow you to control the universe" (on the inside it says, "I was going to buy you a present, but believe me, you'd only be disappointed").
Posted by biggaryc  on  Mon Apr 16, 2007  at  02:58 PM
I'm much more inclined to believe a couple of computer nerds in rollerblades with a laptop can over ride traffic lights than using a universal remote control...

Of course, Hackers was a quality film so I believed everything they did 😉 :lol:
Posted by Nettie  on  Mon Apr 16, 2007  at  05:09 PM
Yes, some emergency vehicles have devices in them that allow the operators to make traffic lights turn green. If I remember correctly, some time back, someone was selling (on eBay perhaps?) the same kind of device.

They're VERY illegal for the general public to own and operate.
Posted by Cranky Media Guy  on  Mon Apr 16, 2007  at  06:09 PM
I knew the timing of traffic lights in my surrounding in Holland and it was always a little joke to pull up to a traffic light (I drive a Rover 827si, which is a big car), point the remote of the alarm towards the trafficlight and press the button. Et voila, the light switched.
The astonished looks on peoples faces still makes me laugh.
Our little bad joke on pedestrians.
Posted by Unfairly Balanced  on  Tue Apr 17, 2007  at  01:55 AM
Razella, in Morse it can mean S/M/E/M/S indeed, but alternatively (depending on where you put the limits between the points and dashes) also:

For a moment I entertained a possible l33t-meaning of "3E7", but the resulting "eet" makes no sense too.
Posted by LaMa  on  Tue Apr 17, 2007  at  06:38 AM
I seem to recall a new story where someone was busted for having one of these devices. It was awhile ago and I don't remember if it happened locally or if I read it somewhere.

I do know these devices exist, but I doubt a universal remote would do the job unless you hacked it pretty good.
Posted by MadCarlotta  on  Tue Apr 17, 2007  at  11:35 AM
I'm inclined to say both of these are total crapola. First off, there isn't any point whatsoever in programming a device intended to assist people in crossing the street with a special secret code to actually allow it to work. Second, when Push-To-Cross signals have actually been tested, they simply inserted a "request" within the cycle, much like an under-the-street traffic approach sensor does - only useful if there's so little traffic you don't need the walk signal in the first place. See

I still get my giggles watching college students hammer away at the buttons as if a dozen presses is going to work any better than one. Well, okay, those students that pay any attention whatsoever to crossing signals in the first place...

As for the emergency vehicle thing, it's highly doubtful that anything like infra-red signals would be used, and certainly not in the sequence of standard remotes, nor would a standard remote be powerful enough. They're intended to be activated from over a block away, and simply forcing a sudden green light (as supposedly demonstrated in the video) would be far more dangerous than just leaving the light alone in the first place.

And finally, I became aware of such a thing when I saw it in action at an intersection I'd used for years - in this case, it turned the lights in all directions red, halting all traffic through the intersection. Far more useful, especially if your emergency vehicle happens to be turning. Red lights in all directions means you can safely use the oncoming lane to go around the traffic halted at the lights, as needed. Having any light green means you're still requiring some drivers to both hear and heed the sirens.
Posted by Just Al  on  Tue Apr 17, 2007  at  04:38 PM
LaMa, in the US it wouldn't make "3E7", as Americans use a different form of Morse code.

"Red lights in all directions means you can safely use the oncoming lane to go around the traffic halted at the lights, as needed."

The ones here leave the light from the direction that the emergency vehicle is coming green. This is useful, because a lot of the roads here are divided, and the vehicle can't simply pull over into the oncoming traffic lane. Plus, there are often other roads leading into the area near the intersection that aren't controlled by the lights; if an ambulance simply pulled into the oncoming traffic lane, it would often be face to face with moving oncoming traffic. Which can be messy.
Posted by Accipiter  on  Tue Apr 17, 2007  at  11:56 PM
This reminds me of The Italian Job, where one of the guys hacked into the traffic control computers to operate the traffic lights.
Posted by Rhea  on  Thu Apr 19, 2007  at  02:03 PM
Rhea said:

"This reminds me of The Italian Job, where one of the guys hacked into the traffic control computers to operate the traffic lights."

I think the writers of that movie stole that plot point from an old Superman TV show episode.
Posted by Cranky Media Guy  on  Fri Apr 20, 2007  at  02:12 AM
Years ago I was interviewed for a job with the section of the city that maintains the traffic signals and was told by the interviewer that once you press the signal button the system locks up and will not accept any further signals for that direction (i.e. north/south or east/west). I see no reason to doubt what I was otld in this. I have noticed that in Tucson if I press the button set up for bicyclists it changes the light faster than if I press the one for pedistrians. I have been told that the emergency vehicles change the light not with any signal but with their siren. The sensor detects the specific pattern of the siren and then acts.
Posted by Christopher Cole  on  Wed Apr 25, 2007  at  06:27 PM
Using the siren might not work too well around here; there are so many different sirens used by different individual fire companies and rescue crews. In fact, the ambulances here have an incredible range of siren sounds on each individual vehicle.

The lights that do have the automatic changing system have little photoreceptor things on them, so they must be receiving some sort of electromagnetic signal from the emergency vehicles.
Posted by Accipiter  on  Wed Apr 25, 2007  at  08:39 PM
Chris Cole: In Tucson I've noticed that the pedestrian lights change whether or not you press the button. It only seems to change it faster at night when there is not any other traffic.
Posted by Razela  on  Thu Apr 26, 2007  at  10:07 AM
Razela, it totally depends upon which intersection you're at. Some indeed have the crosswalk lights active every traffic cycle, but most don't.

Accipiter, I presume several siren sounds could be stored in a computer database which would still work. However, I was thinking about this after my post and realized that sound could bounce around too much in a city and get corrupted from other incidental noises. So, yeah, it's probably a light signal.
Posted by Christopher Cole  on  Thu Apr 26, 2007  at  12:35 PM
Emergency vehicles, here in Oklahoma at least, change the traffic lights with a strobe positioned on the top of the vehicle that flashes at a certain frequency. When detected, the lights will favor the oncoming emergency vehicle. Some morons here believe that flashing their brights a couple of times will force this change. It won't.
Posted by John  on  Thu Apr 26, 2007  at  08:11 PM
No, but the time they spend flashing their brights keeps them occupied until the lights can change, confirming their suspicion that it works and that they have finally hit on the right pattern.
Posted by Kristen55  on  Fri Apr 27, 2007  at  07:46 PM
The "changing trafic lights"-part works finer here in Sweden at least. Not on all lights, but on all the big intersections. You can flash your headligts really fast on-of a cpuple of times, and it will turn green.

Reason: Emeregcy vehicles need free access on all the main streets in order to respond quickly. Ligh sensors (similar to the ones turning on streetlights when it gets dark) instantly reacts to the emergency vehicles highspeed blue/white flashing lights and initializes the "changing to red" for all other directions.

Not all intersections have this function though... In my town i guess its just along the regular respons routes. Over all something like 1 in 5 intersections
Posted by malsum  on  Sat Apr 28, 2007  at  06:11 AM
I cant speak for everyone, but as a Firefighter and EMT I have seen the devices that change the lights for emergency vehicles. Our county jsut started installign them last year, and they arent everywhere yet though. As I said, I cant say its the same for everyone out there, but the ones we use rely on a special light we add onto our aparatus which blinks, I'm assuming at a particular rate. Ontop of the lights, there are cameras which pick this strobing effect up and changes the lights. The light the aparatus is approaching turns green while all other turn red, so that it helps clear the traffic sitting at the red light your approaching.

We do have several gated areas we run in as well, gates to businesses that require a passcode before the gate unlocks and rolls open. We roll up to those, and sound the siren and its supposed to open to that, although i have never actually had the need to run to any of those yet.
Posted by Maverick828  on  Wed May 02, 2007  at  05:10 PM
i cant believe i wasted 10 minutes reading this, to find out that it is not possible,i think i got owned by that video, so good job video guy.
Posted by alen  on  Mon May 14, 2007  at  01:41 AM
Everybody says this is crap, ut has anybody actually tried it??

Also, everybody says this is totally illegal. What law says you can't carry a universal remote?
Posted by Charlie  on  Tue Jun 26, 2007  at  06:59 AM
I say go for it, this guy only got a $50 fine.

Of course a fine would indicate it was illegal activity, but what do I know?
Posted by Charybdis  on  Tue Jun 26, 2007  at  10:12 AM
Charlie, it isn't the remote that's against the law, it's pretending to be an emergency vehicle. By the way, do you know the difference between illegal and unlawful?
Posted by Christopher Cole  on  Tue Jun 26, 2007  at  10:59 AM
yeah, i heard that flashing your brights at a stop light will fool the senor. but i doubt that works. why cant people just be patient??
Posted by nick  on  Wed Jun 27, 2007  at  01:33 PM
Emergency vehicles use a device called an Opticom. It looks like a strobe light and that is what communicates with the little thing on top of the stoplight, not infared which is what remote controls use. I ove how people can make these fake videos and slowly they spread around the net even though no one can get them to work!

Posted by G-Love  on  Sun Nov 04, 2007  at  09:18 PM
In my area, the emergency vehicle pre-emption units work from a strobe light on the emergency vehicle and the Opti-com unit on the signal mast arm is aimed to pick up this strobe (flashing at a certain frequency) at 1500 ft away. In Moorhead MN, across the river, they work sonically from the sirens. There are some infrared preemption units but it's doubtful a remote would be able to trip the signals especially with a 9-1-1 code programmed into it. Regarding the morse code for the pedestrian, it only send a call into the signal controller which will put up the WALK signal during the next non-conflicting phase. So putting some morse code into it won't work. Interestingly however, SEIMENS is big supplier of traffic controller equipment but it still has nothing to do with the pedestrian push button.
Posted by Lyle  on  Tue Nov 13, 2007  at  07:22 AM
it is actually possible. radio waves are used to change traffic lights, infared is also used, but less likely, and strobe detectors. and or a combination of the three. universal remotes do use radio frequenceis and infared signals, so if you had the right frequency, it is entirely very VERY posible to do this. but since this video was posted, the frequency may have, and probly was changed.

dont beleive me? look up traffic lights and universal remotes on wikipedia.

the question is not will it work, it is rather what is the frequency...
Posted by Ryan  on  Fri Nov 16, 2007  at  01:57 PM
As you would expect the facts are far more complex that the discussion here about remotes & flashing lights. Check out:
for info on the two opticom systems.

The first uses infra-red and visible spectrum signals at various low frequencies indicating level of emergency, compressed on that frequency is ID information to validate the signal, such as a unique vehicle code, no they're not so stupid after all!!

The second system is newer and involves using GPS & secure radio communication to signal similar information to the controller. The main advantage here is that it doesn't need line of sight and it can handle multiple vehicle prioritization. In other words 3 fire trucks turning up at the same intersection.
Posted by Chris  on  Tue Jul 22, 2008  at  05:03 PM
why dont one of you try it. i mean why argue that much. just try it
Posted by moneybags  on  Wed Aug 20, 2008  at  08:30 AM
Both of these are myths. Pushing a walk pushbutton only sends a "call" to the signal controller. It only takes one push to lock in the call any additional actuations do nothing.

As for using a universal remote, optical devices do exist that can prempt signals they are high intensity and are intigrated into the strobe systems of emergency vehicles. They flash at a coded rate with a different prefix code for each jurisdiction with additional coding down to individual trucks. If the code does not match exctly then the divice would have no effect. Additionally, the signal would have to be equipped with the opto reciever and most simply are not. Your odds of gettng any code to prempt even one intersection are next to 0. From a 26 year traffic tech.
Posted by MArk B  on  Wed Mar 04, 2009  at  06:14 PM
In my entire lifetime, I have only come across one traffic light where the pedestrian button actually does something. Not sure if it's still functional but it was in London, UK. It was for a pedestrian crossing to Hyde Park. When you click it, the lights for the cars turn red within a few seconds and peds get to walk. The feeling of total control was amazingly satisfying =P
Posted by Sage  on  Thu Jul 30, 2009  at  05:30 PM
The pedestrian button generally adds time to the light so that the pedestrian can safely cross (without having to run) before the light changes. Here, the ped buttons have no effect on causing the light to turn green sooner. This is useful when a busy road intersects a smaller road. With the smaller road, the light stays green for about 5-10 seconds, just enough time for one or two cars to pass. Where if you press the ped button it adds an additional 10-15 seconds depending on the width of the intersection to be crossed. Also, the sensors here are triggered by an audible siren above a certain db, not by infrared or any other form of light. I've heard of people using train horns to trigger the emergency signal, but that attracts a lot of unwanted attention and it is illegal. Besides, it turns all 4 ways red, not green. It's fun to think about ways to foil the system, but these two videos are fake.
Posted by 16vjohn  on  Wed Aug 05, 2009  at  02:52 PM
Its an infra red transmitter that strobes at a set frequency, you can just got get a sine wave generator or a programmable chip and play with the frequencies, or you can get a passive infra red receiver and pick up the frequency off of a ambulance as it passes an intersection. some cities may have the same frequency if that did not change it from the manufacturers set mode, so have fun on road trips. some cities have more sophisticated systems but i'm not getting into that. Spend 5 minutes on google and you will find out how to make one. Dont be an idiot and assume that systems are foul proof, just man up and realize that shit aint that hard.
Posted by thor  on  Sun Dec 06, 2009  at  08:16 PM
In San Diego emergency vehicles are equipped with a strobe light. The majority of traffic lights are equipped with a photo sensor that recognizes the rate of flash of the strobe, turns that light green, and the others red.

If you are far enough away and your headlights are at the correct angle, you CAN change the light by flashing them. HOWEVER, if a police officer sees you do this you ARE going to get a ticket.

And lets face it, if a cop is coming up to a light and it changes because some moron is flashing his headlights, its going to be pretty damn obvious.
Posted by Jesse  on  Wed Dec 09, 2009  at  03:33 PM
True the walk cross button will cause the light to change in Merced but it doesn't work on all of them.
I have tried it several times on many different lights it usually works! As for the other ways they don't work! All of this is illegal.
Posted by Neo  on  Thu Aug 19, 2010  at  05:17 PM
In my town's downtown, they have gotten rid of the buttons altogether. They still have the buttons at most intersections though.

One instance in particular, is one intersection that only shanges when there is traffic at the cross street, so I assume the button sends a request for a cross street green light, so peds can cross the street.

I think that most cross signal buttons do that in my town. They send a "green light" request that changes the signal in the pedestrians favor.
Posted by Northern Pyro  on  Sun Apr 28, 2013  at  12:02 PM
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