Spurious phase in a model for traffic on a bridge
  We present high-precision Monte Carlo data for the phase diagram of a two-species driven diffusive system, reminiscent of traffic across a narrow bridge. Earlier studies reported two phases with broken symmetry; the existence of one of these has been the subject of some debate. We show that the disputed phase disappears for sufficiently large systems and/or sufficiently low bulk mobility. 
David W. Erickson, Gunnar Pruessner, B. Schmittmann and R. K. P. Zia