Roundabout Counts

At TransAnalyst, we work on a set of guidelines covering the count types, counting time windows, count location selection, and count requests. A roundabout is an intersection where traffic travels around a central island in a counterclockwise direction. Vehicles entering the roundabout must corp to vehicles, bicyclists, and pedestrians. Above figure presents the elements of a roundabout.

TransAnalyst’s Roundabout Count Report totals the turning movement volume (TMV) of a roundabout, detailing the entry, circulating and exit flow rate for each roundabout leg, from origin to destination. This data can be used to determine the capacity and performance efficiency of the different roundabout approaches, and the roundabout as a whole. The solution was to observe movements from each leg including entries and exits, direct left turn and circulating volume.

Automating Large Roundabout Studies have implications for private and public agencies. They can significantly reduce the labor required to complete a roundabout count and standardize the accuracy. Anyone with experience counting a roundabout using manual counting from the video will know it is labor intensive and the accuracy wanes compared to a standard intersection count.