PA did this with construction zone cameras. I'm not sure where that landed because its been a while since I've seen one. I successfully appealed my ticket to the magistrate. It initially started as a pilot program and the law requires signage which during the pilot was quite inconspicuous. After the launch the sign was changed to a tiny little thing, about 1/5 the size of the pilot program.

I was going 5 over the reduced speed limit, in the slow lane with rush hour traffic. That thing must've issued thousands of tickets.