Dynamical behavior of a two-dimensional cellular automaton with signal processing

We study the effect of signal cooperation in a 2D cellular-automaton model of traffic flow in cities. Two-state signals, which permit vertical or horizontal passage of vehicles, are introduced to all cells of the automaton system. We simulate the dynamics of vehicles for different samples of signal arrangement. Phase transition occurs between freely moving and jamming phases for the samples. The critical densities for the transition vary as the arrangement is changed. We find a case having the multistage transition between them. The origin of the behavior is examined.