Stability Analysis of Heterogeneous Traffic Flow with Connected and Automated Vehicles: Joint Consideration of Communication Failures and Driver Takeover

Abstract

As a primary stage of connected and automated vehicles (CAVs), the cooperative adaptive cruise control (CACC) system takes some outstanding advantages such as accurate perception and timely reaction, which benefit from vehicular communication, over human-driven vehicles (HDVs). However, these advantages will turn into stability risks in case of communication failures caused by malicious attacks. Thus, this study aims at analyzing the stability of heterogeneous traffic flow with communication failures. We model two types of communication failures: bogus messages and transmission delay, and introduce drivers’ takeovers to react to communication failures. As a result, heterogeneous traffic flow consists of normal CACC vehicles, CACC vehicles with communication failures, and HDVs. Then, a series of numerical analyses, including startup and braking analysis, incidents analysis, and density wave, are proposed to verify the theoretical models and demonstrate their major properties. Besides, a discussion on traffic capacity is presented to analyze the overall impact of communication failures on traffic flow characteristics. The findings can help to investigate the stability evolution of heterogeneous traffic flow and determine the appropriate traffic flow configuration under communication failures.

Impact Analysis of Driver Takeover Under a Connected Environment: A Study of the External Effects on Vehicle Conversions

“…Notably, driver takeover is also double-edged. Frequent takeovers will cause multiple damages, such as reducing traffic capacity and aggravating speed oscillation, since drivers usually decelerate to obtain a larger safety distance from preceding vehicles ( 22 , 23 ). In summary, driver takeover will inevitably contribute to heterogeneity and lead to complicated impacts on the normal operation of the CACC traffic flow.…”

“…Driver takeover: (2) existing works only took the single form of driver takeover, without consideration of the communication heterogeneity caused by driver takeover once the taken-over vehicle loses communication ability. (3) As a result, driver takeover will affect the operation of the entire traffic flow, rather than only the taken-over vehicles and their adjacent vehicles, which has been widely studied in existing works, such as Xiao et al ( 9 , 21 ), Hua et al ( 23 ), and Liu et al ( 35 ). In other words, the external effects of driver takeover are still being neglected currently.…”

“…(3) As a result, driver takeover will affect the operation of the entire traffic flow, rather than only the taken-over vehicles and their adjacent vehicles, which has been widely studied in existing works, such as Xiao et al (9,21), Hua et al (23), and Liu et al (35). In other words, the external effects of driver takeover are still being neglected currently.…”