Capacity of Multi-Lane Roundabout: Methodology Based on Lane Utilization

Traffic roundabout is a priority junction, whose capacity is typically captured by the entry capacities of individual approaches while considering the effects of conflicting flows. For a single-lane roundabout, entry capacity is traditionally analyzed based on gap acceptance where entering vehicles seek an acceptable gap among the circulating flow. An example of this approach can be found in HCM (2000). This paper provides an extension to this approach for multi-lane roundabouts. Through an analysis of lane utilization, entry capacity is estimated for each entry lane. Reserve capacity is then used as a measure to assess the overall roundabout performance. This paper also studies the sensitivity of drivers' lane choices on the overall capacity of traffic roundabouts.