Stability analysis and connected vehicles management for mixed traffic flow with platoons of connected automated vehicles

Abstract

Recently, the market has witnessed the emergence of intelligent vehicles equipped with diverse functionalities. Among these are connected automated vehicles (CAVs) boasting a comprehensive platooning capability, and connected vehicles (CVs), which essentially refer to human-driven vehicles (HVs) equipped with connectivity features. As a result, CAVs, CVs, and regular human-driven vehicles (RVs) will form a mixed CAV-CV-RV flow to affect stability of existing traffic flow, which is an important characteristic of traffic flow operations. This paper investigates stability of this new mixed CAV-CV-RV flow, explores effect of CVs on stability, and proposes CV management strategy aimed at achieving a stable traffic flow. We firstly establish definition of the novel mixed flow comprising CAVs, CVs, and RVs. Subsequently, we present a general analytical approach for evaluating stability of this mixed flow. Then we undertake an empirical study that incorporates car-following models, validated using real experiments involving the aforementioned vehicle types. Based on findings from our stability analysis, we proceed to propose a CV management strategy designed to guarantee stable conditions within this mixed traffic flow. Results indicate the effectiveness of the proposed general analytical method in assessing influences of various system factors on stability of this new mixed flow. Subsequent to an application of the analytical method, empirical study uncovers a noteworthy finding that CVs prove to be more effective than CAVs in ensuring stable conditions within the mixed flow. Then we can manage market proportion of CVs in order to achieve stable mixed flow, according to varying CAV penetration rates. Specifically, some interesting lessons are learned based on the empirical study: (i) to guarantee stable operations of mixed traffic flow, about one third of CVs are needed to be among HVs, before CAVs running on road (CV-RV mixed flow); (ii) management strategy for stable flow requires an increase of minimum CV proportion among HVs from 33% to 55%, as CAV penetration rates increase up to 50%; (iii) when CAV penetration rates are greater than 50%, the required minimum CV proportion for ensuring traffic flow stability decreases with the increase of CAV penetration rates.