One on each side of the road, they look like those shoplifting alarms in stores. Some kind of sniffer for sure. My guess is radiation.
“My guess is radiation.”
I’m guessing you are correct. Perhaps combined with other sensors. I was doing some work at a nuke testing facility and this guy would come out of the little lab building, get into his little Chevy and drive around a track with several sensors set up - poles on either side of the road.
He would go back into the little building and an hour later repeat the process.
I was finally near him at one point when I asked him what he was doing.
“Oh - I’m just running some tests on the various radiation sensors.” He then continued carrying his paper cup with the material in it and set it carefully in his cup holder (personal car!) Obviously dealing with VERY low levels.
The customs and bp use a radar system to “look” through truck/trailers entering into the US. Both at the borders and at some seaports.