The basic criteria for the design of "sustainably safe" bicycle provisions should be based on the cyclists' movements and encounters with other traffic. The four criteria for the cylists' movements are: (1) possible manoeuvres; (2) continuation of the travel without changing the most important characteristics of the traffic provision; (3) predictability: estimating possible changes based on the layout of the infrastructure; and (4) difference between categories or routes: estimating the continuation of a route on the basis of the layout of the infrastructure. The four criteria for the encounters between cyclists and other road users are: (a) travelling in the same direction or crossing; (b) difference in speed and mass between cyclists and, for instance, motor vehicles; (c) frequency of the encounters; and (d) the regulation of the encounters, for example, by a priority rule for cyclists. This paper describes which basic criteria play a role on the different infrastructure levels. These are: (I) network; (II) route; (III) road section and junction; and (IV) "connection". The paper discusses the combinations of the different criteria with the different levels on the basis of the following elementary triangle: function, design and use of traffic provisions. The paper also describes how the safety in a road network can be improved, and how the basic criteria should be used.
Abstract