Priority rules in the netherlands differ from those in surrounding countries. There are in fact no directives or criteria for the introduction of priority measures, and little is known of the effect of such measures. The committee on priority rules has been established to obtain more insight in the effects of priority measures, and to formulate uniform criteria of application on the basis of that insight. In this context it has performed three studies; (1) the prevailing policy on priority measures was investigated by means of a survey among road authorities (svt-report no 24). It appeared that expected effects on road safety constituted the most important argument both pro and contra priority measures. (2) in an effort to evaluate the effect of the introduction of priority measures on safety a before-and-after study was conducted on the accident data for a large number of intersections. A generally positive effect on safety could be demonstrated. (3) the effects of a priority measure on driver behavior were investigated by means of a before-and-after study on a limited number of intersections. It appeared that major roads did not turn into racing circuits at all following priority measures. Moreover, traffic rules in the vicinity of locations were observed more often after the introduction of a priority measure. Ideally, the criteria for the application of priority rules should be based on a hierarchical structure within the relevant road network. The committee recognizes that a hierarchical structure is often absent, particularly in built-up areas. Therefore, it is proposed to base criteria for priority measures on the natural ('informal') behavior that road users display. This behavior derives from perceived road and traffic characteristics, notably from speed and intensity estimates. A set of criteria is proposed in terms of these characteristics. (author/publisher).
Abstract