String Stability of Mixed Traffic Flow with Connected Automated Truck Platoons, Human-Driven Cars, and Trucks on Port Freeways

This study investigates the string stability of a novel, coastal passenger-freight traffic flow mixed with human- and intelligence-driven vehicles on single-lane container port freeways. The mixed flow considered herein comprises scheduled connected and automated truck platoons (CATPs), human-driven cars (HDCs) and container trucks (HDTs). The intelligent driver model (IDM), Adaptive Cruise Control (ACC) and Cooperative Adaptive Cruise Control (CACC) models are utilized to model the car-following behaviors of human-driven cars and trucks, and truck leaders and followers in CATPs, respectively. Stability discriminant equations and numerical simulations are adopted as analytic methodologies. Experimental results show thatthehomogeneous flow of ACC trucks remains stable with the expected time headway larger than a threshold (2.45 s), and the homogeneous flow of CACC trucks with shorter control cycles and larger headways tends to be more stable. All else being equal, as the CATP platoon lengths or the HDC penetration rates increase, the stability of the heterogeneous traffic flow improves gradually. Managerial implications are proposed to improve the stability of the mixed traffic flow considered in this study on container port freeways.