Capacity evaluation of multi-lane traffic roundabout

The entry capacity at a traffic roundabout is typically evaluated for each entry approach, considering the circulating flow and geometric characteristics, e.g., the US highway capacity manual model and the UK Linear Regression model. These models are not appropriate for analyzing multi-lane roundabouts because they do not take into account the possible unequal traffic distribution between the circulating lanes. This paper introduces a lane-based methodology that evaluates the entry capacity for each individual lane while considering the traffic distribution on the circulating lanes. The arrival and circulating flows are formulated based on drivers' lane choice patterns. We then modify and extend the formulae from existing models for the analysis of capacity of multi-lane roundabout. Based on the analysis, we show that higher capacity can be achieved when the utilization on the circulating lanes is more balanced. This result can lead to improved design and management techniques to increase the capacity of multi-lane roundabout.