Traveling SB on Henry Hudson Pky (9A) into NYC or towards the GW Bridge, you will cross the Henry Hudson Bridge and begin flowing down hill. There are three lanes, and while the speed limit is 50, traffic usually flows at 70+ mph. At the bottom of this hill from the toll booths (at the bridge), about 1/2 mile is an on ramp from Riverside Dr. NYPD traffic enforcement sits down the on ramp, completely hidden from view until you have passed and see them in your rear view mirror. If you can stay in the right most lane as they are parked fairly far down the ramp, and probably have difficulty nailing cars across two lanes.
FYI – They alternate between Lidar and Ka bands, and are present at this location religiously.

** I must note, I was left off, after being pulled over doing a claimed 78mph. Against all rules, I on the spot admitted speeding but disputed the speed (FYI – I was truthfully doing 70mph), and told the officer so. I was left off without even a warning, said thanks, and was told I quote, "don’t worry about it, it’s like fishing out here, I’ll go catch another."-it has become a classic in my book.