Extended speed gradient model for traffic flow on two-lane freeways

In this paper, the speed gradient (SG) model is extended to describethe traffic flow on two-lane freeways. Terms related to lane changeare added into the continuity equations and velocity dynamicequations. The empirically observed two-lane phenomena, such as laneusage inversion and lane change rate versus density, are reproducedby extended SG model. The local cluster effect is also investigatedby numerical simulations.