Impact of connected vehicles on the traffic efficiency and PM emissions of mixed traffic flows

With the rapid development of Connected Vehicles (CVs), it is inevitable that Human-driven Vehicles (HVs) and CVs run on the same road in the near future. Besides the traffic efficiency, the sustainable development in society has become more and more concerned with Particulate Matter (PM) emissions very recently. In this work, mixed traffic flows with both CVs and HVs on a two-lane expressway are proposed; the effects of CV penetration rate on the traffic flow, and the PM emission are the focus. The results of the numerical simulation show that the traffic flow is effectively improved as the proportion of CVs increases. However, there are two stages of PM emissions. When the density is lower, the greater the proportion of CVs, the lower the PM emissions. When the density is higher, the situation reverses. Furthermore, traffic flows in two lanes are not the same, and the symmetry is terribly broken when the penetration of CVs is high. In terms of the forward observable interval of CVs, it can limit PM emissions and increase traffic flow. Thus, a high traffic efficiency and a low PM emission require a high CV penetration but an appropriate observable interval.