We introduce the line-based dial-a-ride problem with transfers (liDARPT), a variation of the well-studied dial-a-ride problem (DARP), where vehicles transport requests on-demand but are constrained to operate along a set of lines, and passengers are allowed to transfer between lines on their journey. We develop an event-based solution approach for the liDARPT that relies on the construction of an event-based graph and uses a MILP to find optimal circulations in the event-based graph. To make this solution approach effective, we devise a pre-processing routine to limit the size of the event-based graph. We extensively test our approach on novel benchmark instances, inspired by real-life long-distance bus networks. In our experiments, problem instances with up to 80 requests can be solved to optimality within 15 minutes, and an average of 99.69% of requests are accepted in all instances solved to optimality.
@InProceedings{barth_et_al:OASIcs.ATMOS.2025.17, author = {Barth, Jonas and Reiter, Kendra and Schmidt, Marie}, title = {{The Line-Based Dial-a-Ride Problem with Transfers}}, booktitle = {25th Symposium on Algorithmic Approaches for Transportation Modelling, Optimization, and Systems (ATMOS 2025)}, pages = {17:1--17:20}, series = {Open Access Series in Informatics (OASIcs)}, ISBN = {978-3-95977-404-8}, ISSN = {2190-6807}, year = {2025}, volume = {137}, editor = {Sauer, Jonas and Schmidt, Marie}, publisher = {Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik}, address = {Dagstuhl, Germany}, URL = {https://drops.dagstuhl.de/entities/document/10.4230/OASIcs.ATMOS.2025.17}, URN = {urn:nbn:de:0030-drops-247736}, doi = {10.4230/OASIcs.ATMOS.2025.17}, annote = {Keywords: dial-a-ride, line-based, transfers, on-demand, ridepooling} }