Network-level rhythmic control of heterogeneous automated traffic with buses

TL;DR

This paper introduces a network-level rhythmic control scheme for heterogeneous automated traffic, including buses and private cars, utilizing V2X communication to improve bus punctuality and reduce urban traffic congestion.

Contribution

It proposes the RC-H scheme that organizes mixed traffic rhythmically with virtual platoons, including dedicated ones for buses, and formulates an MILP for optimization with a heuristic solution.

Findings

Bus operation is guaranteed with transit priority.

Travel delays are minimized across demand levels.

The scheme outperforms traffic signal control in high-demand scenarios.

Abstract

Guaranteeing the quality of transit service is of great importance to promote the attractiveness of buses and alleviate urban traffic issues such as congestion and pollution. Emerging technologies of automated driving and V2X communication have the potential to enable the accurate control of vehicles and the efficient organization of traffic to enhance both the schedule adherence of buses and the overall network mobility. This study proposes an innovative network-level control scheme for heterogeneous automated traffic composed of buses and private cars under a full connected and automated environment. Inheriting the idea of network-level rhythmic control proposed by Lin et al. (2020), an augmented rhythmic control scheme for heterogeneous traffic, i.e., RC-H, is established to organize the mixed traffic in a rhythmic manner. Realized virtual platoons are designed for accommodating vehicles to pass through the network, including dedicated virtual platoons for buses to provide exclusive right-of-ways (ROWs) on their trips and regular virtual platoons for private cars along with an optimal assignment plan to minimize the total travel cost. A mixed-integer linear program (MILP) is formulated to optimize the RC-H scheme and a bilevel heuristic solution method is designed to relieve the computational burden of MILP. Numerical examples and simulation experiments are conducted to evaluate the performance of the RC-H scheme under different scenarios. The results show that the bus operation can be guaranteed and the travel delay can be minimized under various demand levels with transit priority. Moreover, compared with traffic signal control strategies, the RC-H scheme has significant advantages in handling massive traffic demand, in terms of both vehicle delay and network throughput.