Going northbound on 355. Right after the Roosevelt road exit. A helicopter notes your speed and relays it to several cops lined up on the side of the highway. They nab you right before you hit the North Avenue exit. It becomes really apparent that there are cops ahead even 1/2 a mile before you get there, but slow down and try as you might – they know who they are after. Pretty shrewd way of enforcement since the speed limit is 55 mph and majority of the driving population on that road drives safely at or above 70 mph. Speeding in a pack becomes practically inefficent here as the helicopter just randomly chooses the fastest of a pack or (in my opinion, and experience) the most expensive car.