In the German Guidelines for Rural Roads (RAL, 2012), the elements of junctions without traffic lights are largely standardized. For different design elements like in particular the design elements to guide right-turning vehicles (including traffic regulation behind a possible triangular traffic island) recommendations should be given by this research project. The study cohort of 100 nodes was both a macroscopic and a microscopic examination subject, in particular detailed accident types were determined from the available accident documentations and analyzed. The driving behaviour both of the cars turning off and turning into the higher-level road studied in 40 selected nodes with combined radar and video technique to analyze in particular time gaps in potentially critical vehicle conflicts. According to the RAL left turning lanes in the higher-level road and road dividers in the subordinated road should be provided to improve road safety. These definitions are confirmed also by this research. Intersections with a triangular traffic island to guide right-turning cars have especially at higher traffic loads a significantly higher accident cost rates than those without this islands. Regarding the right of way after the triangle traffic island particularly the junctions with priority to vehicles turning left have a much higher accident cost rate for conflicts of a left-hand traffic with an oncoming straight driver. At rural road junctions with higher traffic load traffic lights should be installed consequently. At junctions without traffic lights traffic islands to guide the right-turning vehicles should be avoided. (Author/publisher)
Abstract