EngineeringAutomotive EngineeringTransportationTransportation EngineeringVehicle DynamicsIntelligent Transportation SystemsTraffic EngineeringTraffic Flow ManagementTraffic Flow TheoryTraffic OperationsVehicle StabilityFundamental Diagrams Of Traffic FlowLinear StabilityLinear Stability AnalysisLinear Stability TheoryStability FunctionsTraffic Flow ModelingTraffic Shock WavesVehicle Trajectory Analysis
The traffic flow heterogeneity caused by the different car-following dynamics among the different types of vehicles has drawn increasing attention recently. This paper explores the characteristics of the four types of car-truck car-following combinations, car-following-car (CC), car-following-truck (CT), truck-following-car (TC) and truck-following-truck (TT), and their impact on traffic flow stability. A heterogeneous traffic flow model based on the Intelligent Driver car-following model (IDM) is proposed and calibrated using the Next Generation Simulation (NGSIM) vehicle trajectory data. Based on the calibrated model, the characteristics of the car-truck heterogeneous traffic flow are evaluated using the linear stability analysis, fundamental diagrams, and shock wave characteristics. The linear stability analysis identifies two critical factors that can influence the stability of the car-truck heterogeneous traffic flow: the stability functions and the proportions of the four types of car-truck combination. Cars and trucks can both stabilize and destabilize the traffic flow depending on the combination type and the equilibrium velocity. Fundamental diagrams of car-truck heterogeneous flow are found to be determined by the distance headways and proportions of the four types of combination. Moreover, the fundamental diagrams of different car-truck combinations converge to several clusters with the same proportion difference between the CC and TT combinations. The slowing-down effect of trucks on shock wave speed in the car-truck heterogeneous traffic flow is also observed in the simulation.