Traffic Cameras

I always thought that when driving and suddenly a policeman appears from nowhere with a speed gun that wouldn't it be good if you knew it advance that they were going to be there, well now you can because the Hertfordshire police actually warn everyone where they are going to be. I came across the site totally by accident.

http://www.hertsdirect.org/actweb/safetycameras/default.cfm?type=mobile