The effect of ACC vehicles to mixed traffic flow consisting of manual and ACC vehicles

This paper studies the effect of adaptive cruise control (ACC)system on traffic flow by using simulations. The multiple headwayand velocity difference (MHVD) model is used to depict the motion ofACC vehicles, and the simulation results are compared with theoptimal velocity (OV) model which is used to depict the motion ofmanual vehicles. Compared the cases between the manual and the ACCvehicle flow, the fundamental diagram can be classified into fourregions: I, II, III, IV. In low and high density the flux of the twomodels is the same; in region II the free flow region of the MHVDmodel is enlarged, and the flux of the MHVD model is larger thanthat of the OV model; in region III serious jams occur in the OVmodel while the ACC system suppresses the jams in the MHVD model andthe traffic flow is in order, but the flux of the OV model is largerthan that of the MHVD model. Similar phenomena also appeared inmixed traffic flow which consists of manual and ACC vehicles. Theresults indicate that ACC vehicles have significant effect ontraffic flow. The improvement induced by ACC vehicles decreases withthe increasing proportion of ACC vehicles.