Phase transitions in driven diffusive systems with random rates

We study a one-dimensional driven lattice gas model in which quenched random jump rates are associated with the particles. Under suitable conditions on the distribution of jump rates the model displays a phase transition from a high-density `laminar' phase with product measure to a low-density `jammed' phase in which the interparticle spacings have no stationary distribution. Using a waiting time representation the phase transition is shown to be equivalent to a pinning transition of directed polymers with columnar defects. The phenomenon is argued to have a natural realization in traffic flow.