Fundamental diagram of mixed traffic flow considering time lags, platooning intensity, and the degradation of connected automated vehicles

To investigate the impact of connected automated vehicles (CAVs) on the characteristics of mixed traffic flow this paper proposed a fundamental diagram to consider time lags, platooning intensity, and the degradation of CAVs. First, the cooperative adaptive cruise control (CACC), adaptive cruise control (ACC), and intelligent driver model (IDM) are used to describe the car-following behavior characteristics of CAVs, and degraded CAVs (DCAVs), and HDVs, respectively. Second, a fundamental diagram model of mixed traffic flow under different penetration rates of CAVs is derived. The model is related to CAVs degradation, time lags, and platooning intensity. Then, a sensitivity analysis is investigated, including platooning intensity, free-flow speed, and minimum safety distance. Finally, the proposed model is verified by a simulation experiment designed by SUMO. The results show that the free-flow speed, penetration rate, and platooning intensity of CAVs positively affect the traffic capacity and optimal traffic density of mixed traffic flow. On the contrary, the time lags and minimum safety distance harm the traffic capacity and optimal traffic density of mixed traffic flow.