Stability of multi-lane traffic flow

Linear and non-linear stabilities of single-lane traffic flow have been fairly well studied; stable, metastable and unstable states can be well defined. However, stability of multi-lane flow is much less understood. In this paper, we study the effects of the relaxation time in car acceleration/deceleration equation,and of the number of lanes on the stability to unsteady disturbance. Multi-lane flow is less sensitive to the strength of the disturbance; once a weak disturbance causes a triggering lane change, that induces successive disturbances and lane changes, eventually resulting in randomly fluctuated flow. The road capacity is influenced mainly by the value of the relaxation time.