ISP is using 2-3 unit set up at overpasses and interchanges, “spotter” unit (usually an un-marked of some type setting on the Over-Pass) and “Chase unit (s) parked on the entry ramp’s .
The “Spotter” “tag’s” a car or truck and radio’s Information to the “Chase” unit (s).
This is becoming fairly COMMON PRACTICE , even using county road “OVER PASSES” where no inter-change is involved, the “Chase” car (s) are on the side of the Hwy a mile or so away from the overpass .
I’ve seen this practice in several other state’s as well !