A town I live near has the speed limit drop from 65 to 45 on the edge of town. Problem is the sign that says Speed Change Ahead is mounted very close to the speed limit sign. And, the Speed Change Ahead sign is at the top of a hill and on a slight curve. If you want to get down to the new limit on time you are going to have to hit the brakes hard, and they get hot. The cop likes to set at the bottom of the hill and write up tickets. I've seen the truckers get their brakes smoking hot trying to get down to speed on time when they see the cop.
It's a trap. The signs are to close together.