  We consider, in the Aw-Rascle-Zhang traffic flow model, the problem of the
asymptotic stability of constant flows. By using a perturbative approach, we
show the stability in a larger space of perturbation than previous results.
Furthermore, we are able to compute where the perturbation is mainly localised
in space for a given time, based on the localisation of the perturbation
initially. These new ideas can be applied to various other models of hyperbolic
conservation laws with relaxations.
