First save along I-280?

[Clint Eastwood]

That spot is one of the hottest spots for LIDAR on I-280. They usually tag you about a 1/2 mile prior to that particular spot, in the curve leading toward the Vista Point exit. If you pull up the map and look up the hill to the right, it is a Vista Point, and they can hide there easily. They have been known to shoot rear LIDAR from there, though they usually do a frontal shot so as to time it so they are merging into traffic as you pass. That spot is also used by CHP as a LIDAR training location. If you were painted in that exact spot in the map, then they were probably just screwing around with the gear, as it would be a nearly 90-degree off axis shot, and way up the hill. But it was almost certainly CHP, as that very spot is THE most common shoot location - so much so I always visually check as I approach there.

I have also seen them running C/O radar from cars just sitting on the ramp - from the rear.