Unfortunately I believe that they are mainly a revenue raising device more than a preventative or pro-active approach to Road Safety,
One only has to look at the amount of revenue taken from the cameras that is returned to the Road Safety scheme.....
It is ultimately a coffer filling fall-back that can be disguised as Road Safety.
If we better equip our drivers (Tougher Examinations and Courses) being mandatory like Scandinavian countries,
and filter some money into the roads and the services to maintaining the infastructure I think we would see a marked reduction compared to just relying on Speed Cameras.
Just my 2 Cents.