Macroscopic Characteristics of Lane-Changing Traffic

On a multilane roadway, systematic lane changes can seriously disrupt traffic flow and cause capacity reductions. Therefore it is important to understand the characteristics of lane-changing traffic flow. In a previous study, a new variable, lane-changing intensity, was theoretically derived by doubling the contribution to the total density of a lane-changing vehicle during its lane-changing period, and an intensity–density relation was incorporated into the fundamental diagram to capture such bottleneck effects at the aggregate level. In this study, a new interpretation of lane-changing intensity is proposed by following Edie's definition of traffic density. Detailed studies of macroscopic characteristics of lane-changing traffic with 75 min of vehicle trajectories collected for a freeway section on I-80 near San Francisco, California, by FHWA's next-generation simulation project are presented. About 10% misindentified lane changes are excluded. For different time intervals, cell sizes, and locations, the well-definedness of the lane-changing intensity variable and the intensity–density relation are verified.