Robust Dynamic Bus Control: A Distributional Multi-Agent Reinforcement Learning Approach

The bus system is a critical component of sustainable urban transportation. However, the operation of a bus fleet is unstable in nature, and bus bunching has become a common phenomenon that undermines the efficiency and reliability of bus systems. Recently research has demonstrated the promising application of multi-agent reinforcement learning (MARL) to achieve efficient vehicle holding control to avoid bus bunching. However, existing studies essentially overlook the robustness issue resulting from perturbations and anomalies in a transit system, which is of utmost importance when transferring the models for real-world deployment/application. In this study, we integrate implicit quantile network and meta-learning to develop a distributional MARL framework-IQNC-M-to learn continuous control. The proposed IQNC-M framework achieves efficient and reliable control decisions through better handling various uncertainties in real-time transit operations. Specifically, we introduce an interpretable meta-learning module to incorporate global information into the distributional MARL framework, which is an effective solution to circumvent the credit assignment issue in the transit system. In addition, we design a specific learning procedure to train each agent within the framework to pursue a robust control policy. We develop simulation environments based on real-world bus services and passenger demand data and evaluate the proposed framework against both traditional holding control models and state-of-the-art MARL models. Our results show that the proposed IQNC-M framework can effectively handle the general perturbations and various extreme events, such as traffic state perturbations and demand surges, thus improving both efficiency and reliability of the transit system.

Automated summary

The bus system plays a vital role in sustainable urban transportation, but the instability of bus fleet operations often leads to bus bunching, which hampers efficiency and reliability. Previous studies neglect the robustness issue caused by disruptions and irregularities in the transit system, which is crucial for real-world implementation. This research proposes an IQNC-M framework that combines implicit quantile networks and meta-learning to achieve efficient and reliable control decisions by addressing uncertainties in real-time transit operations.