Traffic Light Spoofer for Cyclists

Where I live (IL, USA) the strobe system has a while spotlight that faces each direction that there are sensors. When the strobe on the emergency vehicle triggers the traffic light system, the spotlight facing the same direction of the triggered sensor turns on, to tell the emergency vehicle that the traffic lights have been activated. The emergency vehicles still do not "blast through at full speed" because there's always people who will try to race a red light.

Sometimes even,,,, the people you'd think would know better....

(I do not know if there was emergency triggers or not, from Google Streetview it appears not and the news articles do not mention any)

Most are very simple to trigger, they are only analog circuits and the pulse frequency I have heard is 30 cycles per second.... Except that (in IL) there is a section of the state motor vehicle code that prohibits unauthorized persons or vehicles from triggering these emergency light systems. I would guess anywhere that has these lights will have a similar law.

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Most of these things you see online (to trigger inductive loops) are total BS. Permanent magnets will not trigger an inductive loop at all, because permanent magnets do not display inductance at all.

I have not seen anything in my state's motor vehicle code that says that you cannot artificially trigger an induction loop,,, so I /guess/ it would be legal to have one on a bicycle.

As I have been told, the loops are fed a signal between ~20kHz to ~80kHz. Each loop at an intersection must use a different frequency, to avoid cross-talk inside the control box where the loops converge--so one frequency will *not* work for all traffic sensors. On each loop there is a circuit to detect the phase change of the loop. The phase change you target should probably be negative, as ferrous objects under a metal detector result in negative phase and cars are mostly made of iron alloys.

The frequency of each loop does not change, so it might be possible to make this device relatively simply. The device does not need to sample the frequency and transmit it at the same time, so one antenna could do both jobs (first sample, and then switch to transmitting).

It might work to just attach a coil antenna to a capacitor, that has a resonant frequency of well under 20kHz. I'd think you might need a pretty big ferrite stick to make it work well though.

You can get big 4500u ferrite rods from

AM radio antenna ferrites will not work real well for this; AM radio is at much higher frequencies. ~

Or, you could get off the bike and press the "Walk" button. ;-)

Cheers! Rich

ed

But then all the traffic in front of the emergency vehicle would block in the emergency vehicle. The green light lets the traffic through and pull off to the side.

I wonder if an IR or UV strobe would work? Any cop in front of you will notice a visible-light strobe.

rned

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In our area, a civic group proposed improving a certain ugly 5 lane road through a village by turning it into a boulevard. Opponents claimed it would cause back up traffic, and that people would die in house fires.

One of my friends is a fireman. When he heard that objection, he laughed. He says for a fire truck or ambulance, there is no such obstruction. They simply drive down the oncoming lane when necessary.

- Frank Krygowski

Getting off the bike is too much of a hassle: !

I saw a xenon flash front light for a bike...

Not always possible. Some roads have large concrete barriers between opposing lanes that would cause severe damage to the fire truck or ambulance. I have seen ones over four feet high and several feet thick. They are strong enough to stop a vehicle hitting it head on at

tween

Admittedly, that's true. Worse yet, there are roads where the eastbound and westbound lanes are separated by gullies, rivers or cliffs. But perhaps we can agree those cases are not quite normal?

My friend was talking about the roads in his fire district, which I know well. Nearly all American roads are similar, and present no such problems.

- Frank Krygowski

There are two easy ways to tigger lights assuming there is an induction loop and you have a metal bicycle (another reason to avoid carbon fiber).

- Rare earth magnet (I am fond of expoying a pair in to the lugs of your bike shoes, but many people use regular shoes)

- Lay the bike down in the middle of the induction loop (which is alkward if loaded with stuff or in a busy intersection)

Some cities are starting to include bike specific sensors which trigger lights in the United States, such as Portland, Seattle, and Tucson, but not as many as one would hope and not as wide spread as one would hope either. On occasion, using the Walk button, or crosswalk is simply more practical.

Chris

Most of the main roads around here are protected, but residential roads aren't. Idiot traffic designers seem to be going through another round of islands near intersections, and making shorter left turn lanes. Just a few years ago, they were building center lanes for left turns from either directions that were generally clear of traffic, and available to emergency vehicles.

What they need is good video cameras, and impound the vehicles that don't pull over to allow emergency vehicles through intersections. I was in Ocala, Florida a few days ago, and saw an ambulance have to wait to make a left turn, because the opposing traffic just kept rolling past the entrance to the hospital.

US Hwy. 441 runs N/S through North Central Florida, and quite a bit is separated four lane roadway, yet I rarely drive it without hearing a siren.