Mixed traffic flow of human-driven vehicles and connected autonomous vehicles: String stability and fundamental diagram

Abstract

<abstract><p>The introduction of connected autonomous vehicles (CAVs) gives rise to mixed traffic flow on the roadway, and the coexistence of human-driven vehicles (HVs) and CAVs may last for several decades. CAVs are expected to improve the efficiency of mixed traffic flow. In this paper, the car-following behavior of HVs is modeled by the intelligent driver model (IDM) based on actual trajectory data. The cooperative adaptive cruise control (CACC) model from the PATH laboratory is adopted for the car-following model of CAVs. The string stability of mixed traffic flow is analyzed for different market penetration rates of CAVs, showing that CAVs can effectively prevent stop-and-go waves from forming and propagating. In addition, the fundamental diagram is obtained from the equilibrium state, and the flow-density chart indicates that CAVs can improve the capacity of mixed traffic flow. Furthermore, the periodic boundary condition is designed for numerical simulation according to the infinite length platoon assumption in the analytical approach. The simulation results are consistent with the analytical solutions, suggesting the validity of the string stability and fundamental diagram analysis of mixed traffic flow.</p></abstract>

Application of conditional generative adversarial network to multi-step car-following modeling

“…The initial states [6.66, 13.01, 24.18] of other vehicles are assumed to be equilibrium at speed v e = 15.3 m/s. As in previous studies (Treiber et al, 2006;Ma et al, 2023), the corresponding equilibrium gap distance ( x e ) is derived from the IDM. As the relative speed and acceleration are both zeros at the equilibrium state, they are substituted into Equations ( 8), ( 9), obtaining x e as in Equation ( 10).…”

“…In terms of the stability of CAVs, it is hard to have the CGAN model be analytically solved, because of its black-box nature. But in fact, this periodic boundary simulation environment has been determined to be a feasible method to validate the stability of the car-following model (Ma et al, 2023). It can be seen from Figure 9F that the effect of the perturbation is short-lived when To explore the capacity of mixed traffic flow, we set two virtual detectors on the circular road with an interval of 100 m between them.…”

“…As CGAN car-following model is constructed for CAVs, it should be tested in a mixed traffic flow environment, including HVs and CAVs, to verify its performance. To conduct mixed traffic flow simulation, Ma et al ( 2023 ) has designed a periodic boundary condition. It is an essential experimental approach for traffic flow stability analysis (Li and Shrivastava, 2002 ), which is consistent with the assumption of an infinitely long platoon in the theoretical stability analysis.…”

“…The fundamental diagrams derived from this simulation are compared with the diagrams simulated with mathematical car-following models, i.e., the black scatters in the figures. For simplicity, the contrasted group is not presented here in detail since it is depicted in Ma et al ( 2023 ). The two groups show consistency, indicating the reasonability of proposed data-driven models in terms of traffic flow simulation.…”

Adaptive Vehicular Communication using ALOHA CSMA with Modified Logistic Function (ALOHAMLF)

“…Vehicle-to-vehicle (V2V) communication has the potential to wirelessly transmit data regarding the speed and location using basic safety messages simultaneous use of services that reduce travel time, allow for cooperative autonomous driving, lower maintenance and infrastructure costs, improve energy efficiency, among other benefits. Data storage, privacy and security concerns, IoT sensor energy optimization in vehicles, legal uncertainty, and realtime big data analytics are main issues of developments nowadays [25][26][27][28][29][30].…”