[clearsight]

I am not sure it is done directly by satellite, but through a scanning system built into the bed of the highway itself and then transmitted to the satellite?. Next time you are driving down the interstate around or through a large city notice the dual square pattern on the highway about 2' x 4' in size ( a thin tar line rectangular pattern) occurring about every 1/10th of a mile. That is the magnetic pick-up field which is interrupted each time a vehicle with a chip on the underside passes over. I was under the impression that every vehicle in the u.s. manufactured since 1985 was trackeable, but the article indicates a later date.

[Alberta's Child]

The rectangular pattern you describe is nothing more than a loop detector embedded in the roadway. Large metro areas use these to measure traffic volumes and estimate average highway speeds for various roadway segments, and they are often tied in to other high-tech devices (like variable-message signs) on the system.

These loop detectors don't monitor individual vehicles in any way -- they just detect a heavy object passing over them, estimate the size of the vehicle, and compute the speed. They are basically high-tech versions of those rubber hoses you sometimes see on roads that are used to count traffic.