Traffic flow with multiple quenched disorders.

Abstract

We study heterogeneous traffic dynamics by introducing quenched disorders in all the parameters of Newell's car-following model. Specifically, we consider randomness in the free-flow speed, the jam density, and the backward wave speed. The quenched disorders are modeled using beta distributions. It is observed that, at low densities, the average platoon size and the average speed of vehicles evolve as power laws in time as derived by Ben-Naim, Krapivsky, and Redner. No power-law behavior has been observed in the time evolution of the second moment of density and density distribution function, indicating no equivalence between the present system and the sticky gas. As opposed to a totally asymmetric simple exclusion process, we found no power-law behavior in the stationary gap distribution and the transition from the platoon forming phase to the laminar phase coincides with the free flow to congestion transition and is always of first order, independent of the quenched disorder in the free-flow speed. Using mean-field theory, we derived the gap distribution of vehicles and showed that the phase transition is always of first order, independent of the quenched disorder in the free-flow speed corroborating the simulation results. We also showed that the transition density is the reciprocal of the average gap of vehicles in the platoon in the thermodynamic limit.