Modeling probabilistic traffic breakdown on congested freeway flow

The study aims to develop a novel evolution model of speed perturbations for quantifying the probability of the traffic flow breakdown on congested freeway flow. The model is applicable to freeway operation and management. Time headway, driver behavior, and state transitions with stochastic nature are the most important factors for the breakdown and recovery of a disturbance. Two types of drivers, "adventurers" and "conservatives," and two styles of reacting behavior, "copy" and "shift" are defined to characterize driving behavior. The time headway distributions for arriving and discharging traffic are distinguished for the existence of the "hysteresis" phenomenon. The Monte Carlo simulation is carried out to obtain the estimation of the probability of breakdown (PB). The calculated PB is a monotonically increasing function of freeway flow with an "S" shape. The simulation results indicate that the proposed model can describe the changes in spatial extent and magnitude of a disturbance, which have potential use for future works and field applications.