Infrastructural traffic provisions and their safety aspects; The meaning of the various types of traffic provisions for a sustainably-safe traffic and transport system. The introduction of a sustainably-safe traffic system has made very high requirements of the safety level of the traffic engineering design. The designer must be able to avail himself of sufficient and scientifically founded information about the nature and type of traffic provisions that, in the given circumstances, will be effective. However, from a scientific point of view, the knowledge about safety aspects has many empty spaces. In order to fill them, systematically designed evaluations of road layout and road safety are necessary. Furthermore, the few research results that are available must be optimally used in order to produce generalizable knowledge (e.g. by using meta analysis techniques). At this moment in time, there is a rather fragmentary picture of the safety effects of traffic provisions. The previously conducted studies are often limited in design and difficult to compare with each other. This makes it almost impossible to get a good overview. What could be done in this literature study was to get insight in what is known now, nationally and internationally. The quality of the studies was explicitly weighed in this, and attention was paid to the circumstances and situations that have possibly influenced the effectiveness shown. The literature showed that, relatively speaking, most of the knowledge (accident analyses) is for provisions along (especially North American) rural, single lane through-roads. Traffic provisions can be divided in various ways, e.g. by type of road situation or by type of road user. An inventory was made of the most commonly used divisions. Then it was determined which division for this study was the most suitable and thus would direct us to the further completion of the study. A traffic engineering design consists, in general, of a coherent system of different traffic provisions. The safety effects of a provision are partly dependant on the spatial position in relation to other provisions. Little is known of this dependency. It seems possible and sensible to keep on studying the separate provisions. This study presents a summing-up of essential activities that should lead to more, and more extensive (accident) evaluations of traffic provisions. The priority, in The Netherlands, for new evaluation studies should be for typically sustainably-safe measures. It should also be clear whether an isolated evaluation of such a measure is sensible, or if an evaluation of a number of coherent measures is necessary. Apart from the (known) sustainably-safe requirements, there should be a limited set of criteria that are relevant for the road safety aspects of the traffic engineering design as a whole. Such supplementary criteria regard, in particular, the consistence, continuity, uniformity, and recognizability, for as far as these criteria have not already been incorporated. Finally, a generally applicable set of design procedures should come into existence that guarantees that, for every choice, the safety effects form an emphatic part of the weighing up. This can only be done if there are adequate instruments available (calculation models, checklists, effect estimates, and best practice). Sufficient data must become available for some of these, especially for large-scale inventories.
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