Another method would be to setup a vehicle or box on the side of the road that emulated an emergency vehicle which instructed the light to change to green in the direction that you wanted it (could also be used to change lights to red if put in the perpendicular direction). http://en.wikipedia.org/wiki/Traffic_signal_preemption
I'm not sure which method is most common. The wikipedia article says that IR, acoustic, visible lights, and GPS can be used to change the lights. It would be fun to experiment with different methods of changing them, but would undoubtedly be illegal.
Apparently it's not illegal federally to use these devices to change lights, it might be legal in some states.
I'm not sure which method is most common. The wikipedia article says that IR, acoustic, visible lights, and GPS can be used to change the lights. It would be fun to experiment with different methods of changing them, but would undoubtedly be illegal.
Apparently it's not illegal federally to use these devices to change lights, it might be legal in some states.
http://en.wikipedia.org/wiki/Mobile_Infrared_Transmitter
http://www.themirt.com/