Which points of departure for road safety improvement are connected with integrated network design and road categorization? : requirements for a sustainably safe road network. Since 1997, roads in the Netherlands are categorized into the three categories: through-roads, distributor roads and access roads. However, there are roads and streets that do not fit within these three categories; the so-called grey roads. Grey roads have a distributor function as well as an access function. In 2009, the Information and Technology Platform for Infrastructure, Traffic, Transport and Public Space CROW instituted two working groups to come to a further categorization of these grey roads and streets, both urban and rural. SWOV suggests using a different approach than that used in the 1990s. Firstly SWOV proposes a phase which should precede categorization, viz. the integrated design of a road network. Secondly SWOV proposes using 'safe speeds' as a criterion for the road categorization. Safe speeds are the maximum speeds at which certain conflicts will just miss having serious injury as a consequence. With increasing physical separation, higher safe speeds are possible. Road categorization as we know it in the Netherlands defines road functions: flow, distribution and access. Ideally, this is preceded by a phase in which the socio-economic and demographic factors are analyzed, future traffic flows are studied and, ultimately, the preferred road connections are determined for each individual region. This phase is called the integrated network design. Network design determines to a major extent how traffic can be distributed across the road network; road categorization defines the functions of the connections as stated above. It remains to be seen whether current network design is the most preferred, considering various social objectives (accessibility, road safety and the environment). The same applies to current road categorization. Various methods are available to examine this. The present report will discuss the most important methods for integrated network design; the method which has the most benefits for road safety has been detailed in this report. The road categorization method which is most in keeping with this method has also been worked out, making use of safe speeds. In a separate report (Analysis of regional connections and routes) this method is applied to the Leiden — Den Haag region as a practical example.
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