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Creative Commons Attribution 4.0 International license (CC BY 4.0)
When quoting this document, please refer to the following
DOI: 10.4230/LIPIcs.SEA.2023.16
URN: urn:nbn:de:0030-drops-183664
URL: http://dagstuhl.sunsite.rwth-aachen.de/volltexte/2023/18366/
Großmann, Ernestine ;
Sauer, Jonas ;
Schulz, Christian ;
Steil, Patrick
Arc-Flags Meet Trip-Based Public Transit Routing
Abstract
We present Arc-Flag TB, a journey planning algorithm for public transit networks which combines Trip-Based Public Transit Routing (TB) with the Arc-Flags speedup technique. Compared to previous attempts to apply Arc-Flags to public transit networks, which saw limited success, our approach uses stronger pruning rules to reduce the search space. Our experiments show that Arc-Flag TB achieves a speedup of up to two orders of magnitude over TB, offering query times of less than a millisecond even on large countrywide networks. Compared to the state-of-the-art speedup technique Trip-Based Public Transit Routing Using Condensed Search Trees (TB-CST), our algorithm achieves similar query times but requires significantly less additional memory. Other state-of-the-art algorithms which achieve even faster query times, e.g., Public Transit Labeling, require enormous memory usage. In contrast, Arc-Flag TB offers a tradeoff between query performance and memory usage due to the fact that the number of regions in the network partition required by our algorithm is a configurable parameter. We also identify a previously undiscovered issue in the transfer precomputation of TB, which causes both TB-CST and Arc-Flag TB to answer some queries incorrectly. We provide discussion on how to resolve this issue in the future. Currently, Arc-Flag TB answers 1-6% of queries incorrectly, compared to over 20% for TB-CST on some networks.
BibTeX - Entry
@InProceedings{gromann_et_al:LIPIcs.SEA.2023.16,
author = {Gro{\ss}mann, Ernestine and Sauer, Jonas and Schulz, Christian and Steil, Patrick},
title = {{Arc-Flags Meet Trip-Based Public Transit Routing}},
booktitle = {21st International Symposium on Experimental Algorithms (SEA 2023)},
pages = {16:1--16:18},
series = {Leibniz International Proceedings in Informatics (LIPIcs)},
ISBN = {978-3-95977-279-2},
ISSN = {1868-8969},
year = {2023},
volume = {265},
editor = {Georgiadis, Loukas},
publisher = {Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
address = {Dagstuhl, Germany},
URL = {https://drops.dagstuhl.de/opus/volltexte/2023/18366},
URN = {urn:nbn:de:0030-drops-183664},
doi = {10.4230/LIPIcs.SEA.2023.16},
annote = {Keywords: Public transit routing, graph algorithms, algorithm engineering}
}
