Both Sweden and the Netherlands have introduced plans to reduce the number of fatal traffic accidents and injuries. In Sweden this resulted in the plan 'Vision Zero' (long term goal no fatal accidents), and in the Netherlands the concept of 'Sustainable Safety' was introduced (which can be rephrased as introducing human factors in road design). In this study, the concept of Sustainable Safety in relation to the present design of roundabouts both in Sweden and the Netherlands is explored in a coarse literature review. This review showed that roundabouts have certain advantages over 'regular' intersections. One of the main advantages is that roundabouts are safer than 'regular' intersections. At the same time, however, there is still much unknown about roundabouts. For example, it is still not very clear which design aspects influence traffic safety and traffic behaviour. Moreover, there is a growing diversity of roundabouts. Presently, roundabouts have different radii, number of lanes, width of circulation area and size of the central island. Additionally, the exit or connection can be tangential or right-angled, and bicyclists have separate crossings, are mixed with the traffic on the circulation area or have a separate lane at the outer edge of the circulation area. Presently, the design of a roundabout depends on the kind of road users, traffic flow, and desired speed. This results both in Sweden and the Netherlands in a wide range of sizes and designs of roundabouts, which can elicit uncertain driving behaviour. From a human factors point of view a limited number of roundabouts is recommended. Research, however, is required to address the question of which design aspects of roundabouts influence driving behaviour. (Author/publisher)
Abstract