In road policing, Police target population based behaviours that are not by their nature criminal, but when repeated across the population, cause high levels of road trauma. These behaviour patterns, when observed across a population, are relatively consistent over time. Typically, this results in similar numbers of alcohol related crashes, speed related crashes and a predictable range of crashes occurring. The long term reduction in these trends relies upon a relentless enforcement programme and supporting publicity over many years in order to change engrained behaviours.