Traffic jams in a lattice-gas model

We propose a simple lattice-gas model characterized by two states of atoms, the "thermalized" slate, which is the same as in the standard lattice-gas model, and the "running" state, where the atoms jump in one direction only. The model exhibits the existence of "traffice jams" (bunching of thermalized atoms in compact groups), the nonlinear dependence of mobility on the jump probability, and the hysteresis.