Police enforcement as part of a systems approach
Countries that have successfully reduced road traffic risk have embraced a 'systems approach' to road safety. A systems approach looks at the traffic system as a whole and at the interaction between road, vehicle, and road user in order to identify where there is potential for intervention . It recognises that human beings make errors and that the road traffic system needs to accommodate for these errors. Inspired by the Haddon Matrix (http://www.tsc.berkeley.edu/newsletter/winter05-06/haddon.pdf) , the “systems” approach seeks to identify and rectify the major sources of error or design weakness that contribute to fatal and severe injury crashes, as well as to mitigate the severity and consequences of injury by:
- Reducing exposure to risk
- Preventing road traffic crashes from occurring
- Reducing the severity of injury in the event of a crash
- Reducing the consequences of injury through improved post-collision care
The Swedish Vision Zero  and the Dutch Sustainable Safety vision  are good examples of such a systems approach to road safety.
Within the systems approach, traffic law enforcement is one of the instruments to secure or improve traffic law compliance. In the literature the concepts of ‘traffic law enforcement’ and ‘police enforcement’ are often used interchangeably. However, the concepts differ in width. Traffic law enforcement is wider and covers the entire enforcement chain, from detection of a violation through to the penalty. Police enforcement refers to the actual work of detecting a traffic law violation, apprehending the offender, and securing the evidence needed for his prosecution. Police enforcement can only be effective if it operates in a supportive environment of laws, regulations, and a sensitive penal system. Consequently, the effectiveness of police enforcement cannot be seen in isolation from how the police collaborate with the other parties in the traffic law enforcement chain.
Within the area of police enforcement this web text focuses on speed enforcement. There are two reasons for this. First, the relationship between excess speed and unsafety is well-established and speed control is one of the major spearheads of road safety programmes world-wide. Second, speed enforcement merits special attention in view of the variety of policing methods used to prevent speeding violations and the continuing (technological) developments in this area. It should be kept in mind, however, that police traffic enforcement involves much more than just speed enforcement.