Cycling traffic at turbo roundabouts: some considerations related to cyclist mobility and safety

The growing need for sustainable mobility has led the transport policy-makers as well as population to use more of soft mobility solutions such as pedestrian and cycling traffic. Several European countries are implementing policies for total mobility with less motorization in order to reduce the negative environmental effects generated by industries and transport. In the same time new unconventional types of intersections are developed in order to ensure safer conditions not only for motorized traffic but also for pedestrians and cyclist. One of those is turbo roundabout, at-grade two-lane roundabout, introduced also in urban areas where heterogeneous traffic users are expected and on which traffic safety should be considered carefully. This article aims to analyze the safety of cyclists in different traffic conditions at turbo roundabout with and without separated traffic lanes for cyclists. Through the evaluation of level of service and surrogate safety parameters, the advantages and critical aspects linked to turbo roundabout are highlighted. The research will be conducted on theoretical turbo roundabout with substantial variation in traffic flow. Comparison of the results will allow a better understanding of functionality (level of service, traffic safety) of turbo roundabout in the presence of pedestrians and cyclists of different age. The aim of this article is to present possible solutions to enable safer introduction of cycling traffic at turbo-roundabouts and help defining conditions (number of vehicles, number of cyclist, and number of pedestrians) in which safety of cyclist is questionable and there is need for different solution