Rebalancing Modular Transit Systems: A Hierarchical Graph-Based Optimization Framework for Fleet Sizing and Routing

Fuente: arXiv
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Auteurs principaux: Radvand, Tina, Talebpour, Alireza, Ouyang, Yanfeng
Format: Preprint
Publié: 2025
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author Radvand, Tina
Talebpour, Alireza
Ouyang, Yanfeng
author_facet Radvand, Tina
Talebpour, Alireza
Ouyang, Yanfeng
contents This study addresses the rebalancing of empty modular transit pods between scheduled service trips in fixed-route bus systems. A two-stage hierarchical optimization framework is proposed. The first stage determines the minimum fleet size and initial vehicle assignments by solving a maximum matching problem on a bipartite graph, using a GPU-accelerated push-relabel algorithm. The second stage formulates detailed routing as a series of minimum-cost flow problems on time-space networks. To manage memory usage in large instances, a capped-interval heuristic limits the size of each network by dividing long scheduling intervals into subintervals. Computational experiments on the Manhattan bus network show that the proposed method achieves performance comparable to the full-scale time-space network formulation in terms of objective value, while enabling the solution of instances that are otherwise intractable due to memory limitations.
format Preprint
id arxiv_https___arxiv_org_abs_2508_18643
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Rebalancing Modular Transit Systems: A Hierarchical Graph-Based Optimization Framework for Fleet Sizing and Routing
Radvand, Tina
Talebpour, Alireza
Ouyang, Yanfeng
Optimization and Control
This study addresses the rebalancing of empty modular transit pods between scheduled service trips in fixed-route bus systems. A two-stage hierarchical optimization framework is proposed. The first stage determines the minimum fleet size and initial vehicle assignments by solving a maximum matching problem on a bipartite graph, using a GPU-accelerated push-relabel algorithm. The second stage formulates detailed routing as a series of minimum-cost flow problems on time-space networks. To manage memory usage in large instances, a capped-interval heuristic limits the size of each network by dividing long scheduling intervals into subintervals. Computational experiments on the Manhattan bus network show that the proposed method achieves performance comparable to the full-scale time-space network formulation in terms of objective value, while enabling the solution of instances that are otherwise intractable due to memory limitations.
title Rebalancing Modular Transit Systems: A Hierarchical Graph-Based Optimization Framework for Fleet Sizing and Routing
topic Optimization and Control
url https://arxiv.org/abs/2508.18643