ABSTRACT
ABSTRACT: The article describes adjustments of the original large two-lane roundabout and deals with the assessment of effectiveness of these adjustments from several perspectives. This roundabout is made with a spiral arrangement of lanes on the circular line, instead of the original two-lane orbital lane and some of entrances and exits. Moreover, this roundabout was equipped with traffic lights at some entrances. Pedestrian and bicycle traffic were also changed. To assess the effectiveness of these adjustments road safety was monitored by using video analysis of conflict situations and the capacity of the intersection by using of valid Czech technical conditions and simulation software. Some of the capacity assessment calculations of this spiral roundabout with traffic lights had to be modified because calculations in technical conditions are used separately for roundabouts and intersections with traffic lights.
