Traffic flow impact of mixed heterogeneous platoons on highways: an approach combining driving simulation and microscopic traffic simulation

The connected automated vehicle (CAV) platoons are expected to improve the operational performance of the transportation system. Existing platoon testing processes have used the format of mixed heterogeneous platoons (MHPs), where the leader vehicles are connected human-driven vehicles (CHDVs) and the follower vehicles are CAVs. The impact of this type of MHP on existing highway traffic flow is more complex due to the presence of human drivers, and this impact has yet to be analyzed and quantified. Therefore, this paper takes this type of MHP as the research object and conducts experiments by combining driving simulation and microscopic traffic simulation. The driving behavior of the driver of the MHP's leader vehicle is incorporated into the car-following model by means of a car-following model calibration, and an impact analysis is carried out in terms of multiple dimensions of stability, efficiency, and ecological aspects of the mixed traffic flow under different MHP market penetration rates (MPRs). The results show that MHPs weaken the oscillatory effect of mixed traffic flow and improve mixed traffic flow stability. The MPRs of MHPs are proportional to the road capacity and average speed and antipodal to the average travel time. Also, the MHPs help reduce fuel consumption and pollutant emissions (CO2, CO, NOx, HC, and PMx) during traffic operations. This study can provide theoretical support for the future large-scale application and management of MHPs.