Is there a radio frequency receiver on traffic lights??

[q2bman]

I have noticed dipole and even beam type ant. on several traffic lights. Are these some sort of premption device like the opticom?? If so, how do they work?

[KnightFox]

Possibly a communica device where the traffic department can access the signal to make sure it is functioning properly, adjust timing, syncronize intersections, etc.

As for a Premption device, can't be. The signal needs to know from which direction the emergency vehicle is coming from in order to pre-empt so it knows which light needs to be red, and which needs to be green.

[kx250rider]

YES, there is an RF receiver on all traffic signals in California... They receive radio signals from encoders buried in the street, which sense that a driver is JUST close enough to barely stop in time... And turn every light RED instantly. (at least it seems like it )

Charles

[q2bman]

Well, can the Monarch system (or whatever the new camera system is)identify emergency lighting on emergency vehicles? I am not seeing the opticom recievers anymore. I notice a bunch of the yagi beams now. I wounder if they just turn all red now instead of lighting the way for the e.v.


And man that California can't stop system, if in fact it works that way, seems a good idea. But all signlas have that capability with in ground loop detectors and even the new camera system.

[zetronist]

In NY, the Yagi antennas on traffic lights communicate with the next traffic light down the road. This is done to coordinate cycles to keep the traffic moving. It is probably true of the ones you're speaking about, too.

Take a look at the next traffic light down the road from the one you see. Notice which way the antenna is pointing. On a Yagi, the smallest crossbeam indicates the front of the antenna and the direction it is transmitting. You'll find that the antenna on the next light is pointing back at the first one.

John

[q2bman]

Nice Z. So simple of a concept. Why didn't I think of that. That would be less money due to wire and ditching. Cool and thanks! I'll look today and i'll more than likely see that the beams are pointed at eachother. I feel dumb now.

[AllSafe]

Here they have modems on all of their traffic signals (most of them are Safetran signals) and they have to dial in to them to monitor the signal hardware. They are starting to go to microwave radio on these signals so they can be monitored from service trucks up to two miles away.

[Jim_Ferer]

This could also be something more sophisticated - mesh networking. It's a network topology that depends on relay. Mesh networks can find ways around broken or blocked pathways Some cities are using it to coordinate their bus fleets and so on. Traffic control would be a typical application. The lights can report all sorts of stuff back to the traffic center and instructions can spread over the whole network quickly.

[AllSafe]

This could also be something more sophisticated - mesh networking.

That wouldn't work on our signal hardware- it's way too old!

[Siren Man]

the antennas on the traffic lights are there to receive signals from emergency vehicles. the driver has a remote that sends a signal to the light to make his light turn green so they dont have to wait. thats what they are for.