There are signs but you have to find Waldo for them. Literally. The route 7 ramps are common spots to get pulled over. One time I pulled over to the side of the ramp before I could get a ticket. Of course the cops didn't see me. I walked towards 7 and it was awkward. I had a friend drive me to my car when HOV time was over.

Your friend has been caught and theres nothing to argue over.