Design limits for intersection angles between approach legs of suburban roundabouts

Abstract

Roundabout design guidelines typically offer a step-by-step design process for roundabouts with four approach legs that intersect at right angle in the centre of the central island. If the angle between the approaches is skewed, it is recommended to realign either one or more approach legs. The design limits for intersection angles (i.e. the alignments that do not require repositioning of the approaches) are not listed in most relevant guidelines. This research, conducted in order to define these design limits, is based on theoretical examples of suburban roundabouts with different approach angles and outer radii, designed according to current Croatian and German guidelines.