So maybe you’ve seen 'em and maybe you haven’t, but there’s little devices that sit over highways, aimed down at the road. They look a little like security cameras, but they don’t seem to have any discernable opening.
My wife and I postulated they might be those radar gun/camera contraptions you hear about that mail pictures and speeding tickets to unlucky motorists, but we haven’t gotten any mail yet, so I’m thinking that’s not it.
The other day though, we noticed that there was one stationed on each side of a weigh station. Obviously that has something to do with something. Does anyone know what these are for?
This was in Ohio, if that matters.
And while we’re here, I was at a stoplight and there was some other device attached to what seemed like a small white lamp.
Sometimes I wonder if I should be worried. WHen are the black helicopters coming?
Peter
The ones on the highway are probably radar/camera units. But they are not to catch speeders.
In Houston the freeways are monitored realtime. You get both average traffic speed, and web cams.
see http://traffic.tamu.edu/traffic.html
Most of the traffic lights here have the boxes on them that let emergency vehicles switch the lights.
If you were around Cincinnati, they were most likely monitors for the ARTIMIS traffic system… they’re the folks who run the giant billboards on the interstates around here that kindly inform you that you’re stuck in traffic. Apparently, the average Cincinnatian isn’t bright enough to know that traffic isn’t normally supposed to move at 10mph on the freeway.
We only have a handful of automatic speed traps around here.
If they are traffic camera’s there has to be a place for the camera lens to shoot through… usually a small glass window. You can also usually see a cable sticking out the back since they often have to pivot almost 360 degrees.
Well, everyone else has answered about the camera’s on the freeway, but I’ve seen the boxes on the stop lights that you’re refering to. Those are for cameras that catch people that run red lights. If you watch next couple of times you drive through, you’ll notice that it only flashes when the light is red, and not green.
The things that you are seeing near the weigh stations are for a system called “Pre Pass”. Trucking companies will install a device called a “transponder” in their trucks which sends a signal to these overhead devices. The signal tell the scale operators that the truck has already been weighed or is a certified load and can bypass the scales, this is also why you see some trucks go past the scales without pulling in.
I think starfish is right about the small thing hanging from traffic lights. Most large intersections have small devices that sense the frequency of flashing light from emergency vehicles, and send a signal to the lights at the intersection to change to green to allow the vehicle to pass. Try it yourself. Watch the timing of a light at an intersection, then next time it turns red right as you get there, try flashing your brights repeatedly. It works.
Alternately, if you can get one of those small strobelights, you can make some modifications to the circuitboard that allow it to be tuned to the right frequency. Slap an infrared filter over the front, (so no one will get distracted by the big disco party in your car) then turn it on when you get a red. Presto, chango, the light will turn green.
This doesn’t work in EVERY intersection. I’d say it even works less often than not. But it’s still neat.