Unknown antennas popping up on traffic lights. RFID?

[telxonmaster]

Here in Springfield Missouri, these antennas are popping up on various traffic lights at some of the busier intersections around town. This looks like RFID, which would be bad from a privacy standpoint.
It could also be for emergency vehicle detection to change the lights for them, but if so, i've heard nothing of the city getting such a system.



Maybe a form of vehicle detection?

Any ideas?

[nd5y]

Is there only one antenna at each intersection or are they on every pole?
If there is only one it is probably a data link to a master traffic signal controller.

[telxonmaster]

On every pole aimed right at the lanes of traffic. The signals are linked by fiber, I believe. I spoke to a traffic engineer several months ago (before these antennas started being installed), and he explained how it's all fiber linked to the central traffic engineering department.

In the above picture on the pole with the two red lights showing, there's another antenna right below the street sign.

[Thayne]

Around here they use them to transmit-receive between other signals usually on the same street, take a look and see if they are pointed at other traffic poles within a few blocks--Sometimes the fiber does not go by every traffic light, just major routes then they jump off short distances in other directions using panel antennas & sometimes yagi's

[telxonmaster]

Thayne, these actually point down at the road. about a 45 degree angle. I have seen the yagi's and 2.4 GHZ dishes used for what you describe, and they are usually mounted higher up for a line of sight to another antenna.
These have line of sight to the road only, which is why I was suspicious/ curious about them.

[n5ims]

Probably traffic sensors for controlling the lights. These used to be in the road, but these were maintenance nightmares. They then went to video cameras, but that didn't work when they were blinded by the sun during sunrise or sunset times. They're now using these where they can isolate one or more lanes that have common usage (e.g. turn lanes vs normal traffic lanes vs lanes that may do both) by focusing the sensors on different areas (often there can be several per housing if necessary).

These have been common on the "red light cameras" since they can be aimed more selectivly and on different areas then the traffic sensors. After proving themselves in that application they've been modified to upgrade the older style lane sensors.

As far as your personal privacy goes, they know as much about you and your car as those door opener sensors at most stores do, you're background noise (nobody's there) or you're a moving reflection that triggers the door to open.

[telxonmaster]

n5ims, I figured that is what these might be, but this intersection does have one of the traffic sensing cameras at it, and it is mounted in a way that sunlight probably wouldn't interfere with it. It aims straight down with a fisheye lens. Maybe it's a dual system with cameras and RF sensors?

If a sensor is all it is, then yes it's no privacy concern, but if it is trying to read RFID tags, like the ones in some newer tires, that's a whole different story. (I admit this is highly unlikely, and yes, paranoid/ not practical)

[telxonmaster]

Here are some more pics of another antenna at a different intersection. a bit smaller, but still aiming at the road. I am leaning more towards traffic sensors.

[K9WG]

Probably monitors traffic flow and feeds the information to DOT and the local news services. That way they have notification of any traffic backups etc.

[telxonmaster]

Thanks guys for the input!

I have to agree with those who suggested traffic sensors / detectors, as this seems the most likely case.
And come to think of it, one of the motion detectors on my alarm system uses this same principle, it basically shoots out RF on either the "K" or "Ku" band and looks for a change in the signals reflected back to it.

Thanks again for the help! When a geek like me sees something different, new or "odd", I just have an urge to find out what it is.

[skidplate]

I think you should wear your tin foil hat just in case

[RomeRon]

I have noticed cameras and yagi antennas at red lights in Rome Ga, and wondered what they were, and email to the city manager I found out that they were for replacing the wires installed in the road that trips the traffic light timers.

[mmckenna]

California has those same square traffic sensors all over. They are linked back to the traffic control centers to help them see where traffic is moving and not.

We also have the cameras on the stop lights. It's cheaper and easier to maintain than the loops embedded in the road. They basically see when there is a vehicle waiting.

[rapidcharger]

I agree they are sensors for tripping the lights. Just like the ones above the automatic doors at the supermarket.
The real scary ones are the ones that look like CCTV cameras that are aimed at each lane.

The first time I saw those CCTV style sensors years and years ago I thought big brother might have been spying on us.

If there's no loop detectors and the lights aren't changing on their own, then there's your answer.

[RomeRon]

Originally Posted by rapidcharger

I agree they are sensors for tripping the lights. Just like the ones above the automatic doors at the supermarket.
The real scary ones are the ones that look like CCTV cameras that are aimed at each lane.

The first time I saw those CCTV style sensors years and years ago I thought big brother might have been spying on us.

If there's no loop detectors and the lights aren't changing on their own, then there's your answer.

We have the CCTV cameras that are aimed at each lane. and I was told they could monitor them, but I was told they were not monitoring them.

[telxonmaster]

Springfield has the cameras too, but I was told that the footage is not recorded. It is just used to view current conditions. The traffic engineer I spoke with said that Springfield couldn't afford the amount of server space required to hold that much data, and the cams were intended for observing current conditions. Although it's still not a far step from Orwellian big brother, it's better than storing all that data.

[MOTOROLANUT]

Originally Posted by telxonmaster

Springfield has the cameras too, but I was told that the footage is not recorded. It is just used to view current conditions. The traffic engineer I spoke with said that Springfield couldn't afford the amount of server space required to hold that much data, and the cams were intended for observing current conditions. Although it's still not a far step from Orwellian big brother, it's better than storing all that data.

Anyone know what frequency these traffic cams operate on? I see what appears to be directional Yagi antennas installed at intersections here in WV.

[nd5y]

The traffic sensor cameras don't transmit video. The yagi antennas are probably for the signal controller. They are usually in the 902-928 MHz ISM band but you should be able to tell what band is used by the size and type of antenna.

[telxonmaster]

Some of the antennas here in Springfield Mo. are used for temporary links until they get fiber to the different intersections. the "dish" ones are 2.4GHz (not wifi).

[Cameron314]

The first picture you posted is a vehicle sensor, it would be a replacement for the loops that are cut into the pavement in front of the stop line that they have to replace every time they repave. A lot of MoDOT intersections have the a camera looking version of this high up the the street light arm over the stop light, those do the same thing.

The real cameras are what you called the fish eye, they are dome cameras that sent their signals back to the traffic control center by the fiber that links the intersections or in cases where there isn't fiber yet via the Cisco PtP radio links. You can check at the cameras here Ozarks Traffic Information Home: Traffic Cameras & Incidents