A Formulation of the Relaxation Phenomenon for Lane Changing Dynamics in an Arbitrary Car Following Model

Abstract

Lane changing dynamics are an important part of traffic microsimulation and are vital for modeling weaving sections and merge bottlenecks. However, there is often much more emphasis placed on car following and gap acceptance models, whereas lane changing dynamics such as tactical, cooperation, and relaxation models receive comparatively little attention. This paper develops a general relaxation model which can be applied to an arbitrary parametric or nonparametric microsimulation model. The relaxation model modifies car following dynamics after a lane change, when vehicles can be far from equilibrium. Relaxation prevents car following models from reacting too strongly to the changes in space headway caused by lane changing, leading to more accurate and realistic simulated trajectories. We also show that relaxation is necessary for correctly simulating traffic breakdown with realistic values of capacity drop.
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Speed time plots of calibrated trajectories (NM = Newell Model). Many of the Newell trajectories (e.g. middle top/bottom panels) appear unrealistic because of strong accelerations after lane changes. The bottom left panel shows an example of this same effect for the IDM no relax and IDM SKA.