Flanders already has average speed checks on certain motorways and trunk roads, but via fixed SPECS cameras measuring your speed over a longer distance. The new plans are about mobile speed camera systems.
The mobile systems are of course a lot more interesting to the police. They can be used at any moment at any place, e.g. where road works are being carried out.
The present average speed cameras have already proved their worth, as they triggered a reduction of the number of accidents.