“…The traffic model considered in this paper is a system of 2 × 2 conservation laws; it belongs to the class of macroscopic second order models as the famous Aw-Rascle-Zhang model, see [1,19]. As the name Phase Transition suggests, the model is characterized by two different phases, the free one and the congested one; see [2,4,5,7,8,10,14,16,17] and the references therein for similar descriptions. The Phase Transition model we consider here is derived from the famous Lighthill-Whitham-Richards one [15,18] by assuming that different drivers may have different maximal speeds.…”