Cooperative adaptive cruise control (CACC) vehicles need vehicle-to-vehicle (V2 V) communication to achieve CACC function. When a CACC vehicle follows a manual-driven vehicle (MDV) without V2 V communication, it needs degenerate to adaptive cruise control (ACC). By using real experiments, California PATH program indicated that ACC vehicles are apt to be unstable, which may have negative influence on fuel consumption and traffic emissions. Hence, this paper studies the impacts of the mixed CACC-MDV traffic on fuel consumption and emissions, by taking into consideration partial degenerations from stable CACC vehicles to unstable ACC vehicles. To deal with this, microscopic simulations were adopted by using car-following models. Then, an appropriate emission model was used for evaluating the emission impacts under different CACC market penetration rates (MPRs). In order to obtain reliable evaluation results, the models validated by PATH program using real experimental data were employed as the CACC and ACC car-following models. In addition, we also analytically investigated stability of the mixed traffic flow under different CACC MPRs, in order to explore its relationship with the emission impacts. The results show that the fuel consumption and emissions firstly increase and then decrease with the increase of the CACC MPR. This means the mixed traffic under some ranges of CACC MPRs will produce more fuel consumption and emissions, compared with the full MDVs traffic. It indicates that stability situations of the mixed traffic qualitatively influence the impact trend of CACC MPRs on fuel consumption and emissions. Then, V2 V communication equipments on MDVs are not only encouraging but also essential to avoid the deterioration of fuel consumption and emissions of the mixed traffic flow.

Implications

From a novel perspective, emission impacts of mixed CACC-HDVs flow are studied by considering partial degeneration from stable CACC to unstable ACC. It showed that stability of the mixed traffic flow qualitatively influences the impact trend of emissions with respect to CACC market penetration rates (MPR). Full V2 V communication environment is essential to reduce fuel consumption and emissions in the mixed traffic flow.

中文翻译：

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混合（合作）自适应巡航控制交通流量的纵向排放评估及其与稳定性的关系。

协作式自适应巡航控制（CACC）车辆需要车对车（V2 V）通信以实现CACC功能。当CACC车辆跟随没有V2 V通信的手动驾驶车辆（MDV）时，需要退化为自适应巡航控制（ACC）。通过实际实验，California PATH程序表明ACC车辆容易变得不稳定，这可能会对燃油消耗和交通排放产生负面影响。因此，本文通过考虑从稳定的CACC车辆到不稳定的ACC车辆的部分退化，研究了混合CACC-MDV交通对燃料消耗和排放的影响。为了解决这个问题，通过使用汽车跟随模型来进行微观模拟。然后，在不同的CACC市场渗透率（MPR）下，使用适当的排放模型来评估排放影响。为了获得可靠的评估结果，采用PATH程序使用真实实验数据验证的模型作为CACC和ACC跟踪模型。此外，我们还分析研究了不同CACC MPR下混合交通流的稳定性，以探讨其与排放影响之间的关系。结果表明，随着CACC MPR的增加，油耗和排放量先增加后减少。这意味着与MDV的全部流量相比，CACC MPR的某些范围下的混合流量将产生更多的燃料消耗和排放。这表明混合交通的稳定状况从质量上影响了CACC MPR对燃油消耗和排放的影响趋势。然后，MDV上的V2 V通信设备不仅令人鼓舞，而且对于避免油耗和混合交通流排放的恶化也至关重要。

含义

从新颖的角度，通过考虑从稳定CACC到不稳定ACC的部分退化，研究了混合CACC-HDV流动的排放影响。结果表明，混合交通流量的稳定性从质量上影响了排放相对于CACC市场渗透率（MPR）的影响趋势。完整的V2 V通信环境对于减少混合交通流中的油耗和排放至关重要。