The paper presents the basic design rules of turbo roundabouts proposed in Russian Federation. Before development of the national manual draft the project group analyzed manuals and working document of several countries (Croatian, Dutch, German, Poland and Slovenia). As result of comparative analysis the draft of turbo roundabouts design manual considering spiral geometry as a basis. Defining a relevant design vehicle and following roundabout templates were the first basic problem. Circular lane width and distances between edge lines of spiral roundabout, entry and exit path radii were chosen for the design vehicle which is appointed as typical Russian semitrailer. The design vehicle swept path analysis and turning trajectories are executed basing on CAD software simulation. In case of Russia especially specific turbo roundabout design problem is a set geometric and construction parapets of lane dividers. The main feature of the Russian conditions is long severe winter and high probability of heavy snowfalls. Thus, winter operation contents becomes the main factor of the choice of the divider solution. In accordance with winter conditions as design period the consideration was the flat divider which cross section width is 1,2 m and edges as a road marking. The developed decisions have to provide a possibility of snow removal and also visual perception of the lanes on turbo roundabouts in winter conditions.

turboroundabouts, winter conditions, lane dividers, geometry design