Alleviating bus bunching via modular vehicles
Document Type
Journal Article
Publication Date
2024
Subject Area
mode - bus, operations - capacity, operations - crowding, planning - methods, planning - service level
Keywords
Bus bunching, Modular autonomous vehicles (MAVs)
Abstract
The notorious phenomenon of bus bunching prevailing in uncontrolled bus systems produces irregular headways and downgrades the level of service by increasing passengers’ expected waiting time. Modular autonomous vehicles (MAVs), due to their ability to split and merge en route, have the potential to help both late and early buses recover from schedule deviation while providing continuous service. In this paper, we propose a novel bus bunching alleviation strategy for MAV-aided transit systems. We first consider a soft vehicle capacity constraint and establish a continuum approximation (CA) model (Model I) to capture the system dynamics intertwined with the MAV splitting and merging operations, and then establish an infinite-horizon stochastic optimization model to determine the optimal splitting and merging strategy. To capture the reality that passengers may fail to board an overcrowded bus, we propose a second model (Model II) by extending Model I to accommodate a hard vehicle capacity constraint. Based on the characteristics of the problem, we develop a customized deep Q-network (DQN) algorithm with multiple relay buffers and a penalized ruin state applicable for both models to optimize the strategy for each MAV. Numerical results show that the strategy obtained via the DQN algorithm is an effective bunch-proof strategy and has a better performance than the myopic strategy for MAV-aided systems and the two-way-looking strategy for conventional bus systems. Sensitivity analyses are also conducted to examine the effectiveness and benefits of the proposed strategy across different operation scenarios.
Rights
Permission to publish the abstract has been given by Elsevier, copyright remains with them.
Recommended Citation
Liu, Y., Chen, Z., & Wang, X. (2024). Alleviating bus bunching via modular vehicles. Transportation Research Part B: Methodological, 189, 103051.
Comments
Transportation Research Part B Home Page:
http://www.sciencedirect.com/science/journal/01912615