My wife and I just got back from a trip through New England. While traveling through New Hampshire, we got a hoot when we saw a portable warning sign on the side of the road that said, "Slow State Police". We first thought that a seat belt or DL check was ahead. When we saw a couple of patrol cars we thought, "How stupid does someone have to be to get caught at an announced speed trap?" We were wrong. It turns out, that by the time we saw the sign, we had already been clocked by aircraft. Fortunately I adhere to the speed limit. Here is a story: NH State Troopers Use Eye In The Sky To Catch Speeding Drivers « CBS Boston