Macroscopic Modelling and Simulation of ACC and CACC Traffic

The incorporation of a macroscopic approach reflecting Adaptive Cruise Control (ACC) and Cooperative Adaptive Cruise Control (CACC) traffic dynamics in a gas-kinetic (GKT) traffic flow model is presented. The approach is a novel one and is based on the introduction of a relaxation term that satisfies the time/space-gap principle of ACC or CACC systems. The relaxation time is assigned on multiple leading vehicles in the CACC case, whereas in the ACC case this relaxation time is only assigned to the direct leading vehicle. Numerical simulations investigate the effect of ACC and CACC to traffic flow macroscopic stability with respect to perturbations introduced in a ring road and to flow characteristics in open freeways with merging flows at an on-ramp. Following from the results, it can be deduced that CACC vehicles increase the stabilization of traffic flow, compared to ACC ones. Further, the proposed CACC approach can further improve the dynamic equilibrium capacity and traffic dynamics, especially at on-ramp bottlenecks.