A concept of a car-following system that consists of a car-following equation together with a set of constraints is appropriate for microsimulation models. Recognition was given to the asynchronous condition in the leader-follower relationship as it relates to the internal dynamics in simulation models. The Pitt car-following equation and criticisms of it were evaluated. Two modifications to the Pitt car-following equation were introduced that address the criticisms. The first modification consists of a change in the method by which the perception-reaction time is handled, eliminating the requirement that it must be much less than the simulation time step and removing a discrepancy between the application of car-following and emergency deceleration. The second modification consists of a multiplicative factor, K, that addresses issues related to overdamping and the dead band, which have been raised concerning the original formulation of the Pitt model. An Excel spreadsheet was used to implement the car-following system, and a series of scenarios were simulated. The results of the scenarios indicated that the addition of the factor K has a substantial effect on the behavior of vehicles in a platoon when the leader of the platoon is subjected to a deceleration. Issues of calibration and validation were also addressed.
Abstract