There are two main methods of speed enforcement. The first one is to check drivers alongside the road and stop offenders. In the literature this is often called stationary enforcement or physical policing. Physical policing makes use of manned (visible or invisible) observation unit and a manned (visible) apprehension unit where the offenders are stopped. When physical policing is randomised in time and location over a large part of the road network, this type of enforcement is called random road watch or network-wide random enforcement.
The second method is to detect speed offenders by means of a speed camera and to send them a fine or a notification by mail. Speed cameras can be used fulltime at fixed locations (fixed cameras) or can be rotated over different locations (mobile cameras). Speed cameras can operate automatically (unmanned) or as part of a manned control (either in a visible or in a hidden car or van).