Why This Matters

When transit buses break down or experience incidents, agencies must quickly decide which substitute vehicles to dispatch to cover affected trips. This decision-making problem combines aspects of scheduling, resource allocation, and real-time optimization. The work is important because it addresses the practical challenge of making good decisions under uncertainty with limited time and information, using both planning and learning techniques to balance the need for speed with solution quality.

What We Did

This work develops a software framework for public transit stoning and dispatch that solves the problem of optimally assigning substitute buses when the fixed-line fleet experiences disruptions. The system models the problem as a semi-Markov decision process and uses Monte Carlo tree search to find good dispatching decisions. The approach includes both offline optimization for planned scheduling and online components for responding to real-time disruptions, with integration into a complete transit management system.

Key Results

The MCTS-based approach successfully solves the stoning and dispatch problem for real transit instances, outperforming greedy baseline approaches. The system demonstrates the ability to handle both pre-planned scheduling for known trip patterns and dynamic reallocation when disruptions occur. Results show how tree search methods can effectively explore the space of alternative dispatching strategies to find solutions that minimize passenger impact.

Full Abstract

Cite This Paper

@inproceedings{talusan2024ICCPS,
  author = {Talusan, Jose Paolo and Han, Chaeeun and Mukhopadhyay, Ayan and Laszka, Aron and Freudberg, Dan and Dubey, Abhishek},
  booktitle = {Proceedings of the ACM/IEEE 15th International Conference on Cyber-Physical Systems (ICCPS)},
  title = {An Online Approach to Solving Public Transit Stationing and Dispatch Problem},
  year = {2024},
  address = {New York, NY, USA},
  publisher = {Association for Computing Machinery},
  series = {ICCPS '24},
  abstract = {Public bus transit systems provide critical transportation services for large sections of modern communities. On-time performance and maintaining the reliable quality of service is therefore very important. Unfortunately, disruptions caused by overcrowding, vehicular failures, and road accidents often lead to service performance degradation. Though transit agencies keep a limited number of vehicles in reserve and dispatch them to relieve the affected routes during disruptions, the procedure is often ad-hoc and has to rely on human experience and intuition to allocate resources (vehicles) to affected trips under uncertainty. In this paper, we describe a principled approach using non-myopic sequential decision procedures to solve the problem and decide (a) if it is advantageous to anticipate problems and proactively station transit buses near areas with high-likelihood of disruptions and (b) decide if and which vehicle to dispatch to a particular problem. Our approach was developed in partnership with the Metropolitan Transportation Authority for a mid-sized city in the USA and models the system as a semi-Markov decision problem (solved as a Monte-Carlo tree search procedure) and shows that it is possible to obtain an answer to these two coupled decision problems in a way that maximizes the overall reward (number of people served). We sample many possible futures from generative models, each is assigned to a tree and processed using root parallelization. We validate our approach using 3 years of data from our partner agency. Our experiments show that the proposed framework serves 2% more passengers while reducing deadhead miles by 40%.},
  contribution = {lead},
  note = {Best paper award},
  acceptance = {28.2},
  location = {Hong Kong, China},
  numpages = {10},
  keywords = {transit dispatch, vehicle routing, disruption response, online optimization, Monte Carlo tree search, resource allocation, real-time decision-making}
}
Quick Info
Year 2024
Series ICCPS '24
Keywords
transit dispatch vehicle routing disruption response online optimization Monte Carlo tree search resource allocation real-time decision-making
Research Areas
transit emergency POMDP middleware
Search Tags

Online, Approach, Solving, Public, Transit, Stationing, Dispatch, Problem, transit dispatch, vehicle routing, disruption response, online optimization, Monte Carlo tree search, resource allocation, real-time decision-making, transit, emergency, POMDP, middleware, 2024, Talusan, Han, Mukhopadhyay, Laszka, Freudberg, Dubey, ICCPS24