How do fire trucks and police cars get the red stop lights to change green from afar???

Question

Is it a thing on the lights on in the car;or both???...Thanks for your answer...Tom Science 4

Answer 1

Phew... answers are all over the map on this one, huh?

No it is not a myth. The technology is called "Traffic Signal Preemption" and is very real.

Once upon a time, the signals were triggered by light pulses of an approriate candela, however, these were found to be unreliable and often had false responses. It was also easier for the general public to manipulate. Most of these systems have now been discontinued.

The new system uses infrared transmitters and receivers.

There are a few things you have to understand. First, not all traffic lights can be controlled in this matter. To have traffic lights that will respond, they have to be equipped with the proper controllers and have infrared "receivers" pointed in the direction to receive the incoming signal from the public owned vechile.

Secondly, you are correct in that the approaching vehicle is also equipped with a transmitter that emits the infrared beam that triggers the signal to change. Most of the time, the sigal will immediately halt normal operations and go yellow, then red, in all directions except the direction of the oncoming vechicle which triggered the mode. Sometimes the green will even flash to let the driver know the signal has been sucessfuly preempted. Once the vechicle clears the intersection, the traffic signal will resume normal operation usually within 10 to 30 seconds.

Some cutting edge technology is emerging that also uses GPS technology.

I am providing a number of links which explain the old, current, and newest technology and some which sell it. Understand, affidavits have to be signed and proof must be supplied that the purchase is for a bonafide public service vechile. (It's not always just emergency vechiles either. In some cities, funeral vehicles, buses, and even undercover vehicles are equipped.)

Also, as with any device of this type, you do get a black market. However, it is a criminal offence to own or operate one without operation AND most of the intersections that are equipped with this technology in my city are ALSO equipped with cameras!

(I live in Canton, Ohio and they are everywhere here. I see them work all the time.)

Answer 2

This is a myth.... Police and firetrucks cannot change traffic lights... Here is why: lets say a police car is driving 80 miles an hour toward a red light, at that speed he will be approaching the intersection very quick... the traffic going the other way would have green lights at the time.... now if they changed to green, for the police car, the other lights would have to change to red, but before they change to red, they have to chage to yellow, and allow cars too close to the light a chance to get throgh the intersection. By the time this all takes place the cop would already be throught the intersection, and well on his way... This myth has been around for a long time.... so flashing your lights in hopes that the red light will become green is almost as effective as yelling at the red light.

Answer 3

Fire Trucks Lights

Answer 4

those things on top of the lights the ones that have two pointy tubs with them they recieve frequencies that the ambulance fire trucks and police send out when necessary and they change the lights as fast as they can so they dont get a red light and stop all of the sudden making them take more time to start up again. they do this all the time in california and it is illegal to have the device that makes this happen in your car in some states like new york but in ca its legal to own it and have it in your car but ironcily its illegal to push the button.. talk about cookies in the cookie jar.

Answer 5

It's a type of remote they have in their vehicles. They're used at certain intersections in Chicago, Michigan, Ohio, etc. I found a link for the device.

Usually, the 14 Hz strobe will trigger the lights to change and there are commercial devices available that emulate the 14 Hz strobe with non-visible light. They were outlawed in 2005.

I've found a link on wikipedia.

UPDATE: I was just at an intersection waiting for a green light. As soon as it turned green, it turned yellow before anybody could go. Two seconds later, and ambulance appeared from the other side of an overpass. It's obviously not a myth.

Answer 6

well I suppose they could have been those colors... I think the main point of the coloring system was to differenciate. Bright color, like red captures the attention and tells us to stop- yellow is not quite the same, but still attention grabbing. Green is mellow, so we're allowed to cruze on through. Yet green is totally a different color scheme so it's easy to tell the difference from a distance. Personly, I think orange would be awesome in place of yellow... but then it'd be a litttttle too close to red... I think I'd stop when I wasn't supposed to... (and probably get honked at~! lol)

Answer 7

If you look at the top of the traffic lights you will see a little box they police cars etc. have a thing in their cars that they push to change the lights so to answer you question they both have them

Answer 8

It is a mechanism that is "triggered" by the lights atop the vehicles. The strobe is identified as emergency and the light lights up appropriately, just flashing your beams might not work because they won't perform the same actions movements or colors the roof lights do.

Answer 9

The traffic signal is equipped with a sensor that detects the sound from a siren but only a certain pitch.if you notice,the sound of an emergency vehicle's siren changes when nearing an intersection.the operator changes the sound by switching it to what they call the "wail" feature to activate the traffic signal to red at all throughways and back to the "yelp" feature when traveling on straightaways.....it is not a specific remote device.

Answer 10

If it were possible there would be a huge black market for the technology....Everybody would want the capability to do the same......Think about it, anybody with a few dollars could buy the remote switches or the frequency and just drive around changing the lights...

BTW, I also just read it is a federal law to own, sell, or make anything that manipulates to traffic signals.... Try to buy one from any one of the sites that offer one...You might get a knock on your door soon.....