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