A previous German Insurers Accident Research (UDV) study carried out in 2012 had shown that cycle paths around the perimeter of roundabouts with priority for cyclists at the crossings are associated with more accidents than other forms of provision for cyclists. The new study shows how road safety for cyclists can be improved on cycle paths like this.
The results of the new study show, above all, that the selection of geometric elements such as the external diameter of the roundabout (greater than 30 meters), the diameter of the central island (greater than 13 meters) and the width of the inner ring (less than 3 meters) have a positive influence on the safety of cyclists. The inner ring should be structurally differentiated from the carriageway and keep speeds down. In addition, the cycling traffic should be routed as close to the roundabout as possible in a one-way system. If two-way traffic is unavoidable, the cycle crossings should be marked with pictograms and indications of the directions of travel.