Abstract

We model city traffic by a cellular automaton. It consist of a row of interacting cars through a sequence of traffic lights, synchronized by a propagating green signal. We start the system from an initial jammed condition of low density, which shows the same scaling laws previously found [1]. However, for large initial jammed densities, the emergence of spatial variability in the behavior of the cars along the sequence of traffic lights, produce the breakdown of the scaling laws. This spatial disorder corresponds to a different attractor of the system, from that of the small initial jammed densities. As we include velocity perturbations in the dynamics of the cars, all these attractors collapse to a single noisy attractor for all initial jammed densities. However, this emergent state, shows what seems a stochastic resonance in which the average traffic velocity increases with respect to that of the system without noise.