Speed enforcement in relation to other road safety measures

Preferably, a road safety philosophy not only specifies possible road safety measures, but also specifies how different road safety measures, including road design, setting speed limits, enforcement, etc. are related to one another in a logical and hierarchical manner, and when and where certain measures must be taken, rather than others. For example, according to the Dutch Sustainable Safety vision, speed enforcement should always be considered in combination with other speed management measures. It should only be carried out when speeding demonstrably contributes to a bad safety record of a road, and when other measures (such as setting safe and credible speed limits, changing the road infrastructure, providing road users with adequate information about limits on road sections) are not possible or insufficient to make road users comply with the speed limits.

Research informs us that different measures can be effective in controlling speed. For example, Mountain, Hirst and Maher [46] compared speed and safety effects of engineering measures and enforcement by fixed speed cameras. Using a study design that controlled for trends in crashes, regression-to-the mean effects and changes in traffic volume, they found that engineering schemes including vertical deflections (speed humps, cushions) prevented 44% of personal injury crashes. Furthermore, they found that engineering schemes with horizontal features resulted in a decrease of 29% in personal injury crashes and speed cameras reduced the personal injury crashes by 22%.

The idea behind an integrated speed management approach is to seek for the best possible synergies between the various individual measures. Isolated measures will have an impact but are most likely not the most effective way to achieve a durable reduction in speed [49].

Rule 2:

To achieve collective safety benefits by reducing speeds, a systematic, integrated speed management policy is necessary. Speed enforcement is one of the elements of an integrated speed management approach.