Traffic safety evaluation of mixed traffic flow considering the maximum platoon size of connected automated vehicles

Abstract

In this paper, we investigate the influence of the maximum platoon size of connected automated vehicles (CAVs) on the traffic safety of traffic flow mixed with human-driven vehicles (HDVs) and CAVs. First, the spatial distributions of vehicles within the mixed traffic flow are analyzed. On this basis, the car-following characteristics of different vehicles are obtained. Second, the distribution probability of the four car-following modes in mixed traffic flow is derived based on the maximum platoon size of CAVs. Then, the intelligent driver model (IDM), gap-regulating model, cooperative adaptive cruise control (CACC) model, and adaptive cruise control (ACC) model are used to capture the four different car-following modes, respectively. Finally, multiple safety measures, such as the coefficient of variation of the vehicle speed, time exposed time-to-collision (TET), and time-integrated time-to-collision (TIT), are adopted to evaluate the safety of mixed traffic flow. Moreover, the impact of platoon size on the safety of mixed traffic flows is evaluated based on a numerical simulation. The results demonstrate that the magnitude of the impact of the platoon size of CAVs on the safety of mixed traffic flow is related to the penetration rate of CAVs.