Many efforts have been done in the last years to model public transport timetables in order to find optimal routes. The proposed models can be classified into two types: those representing the timetable as an array, and those representing it as a graph. The array-based models have been shown to be very effective in terms of query time, while the graph-based models usually answer queries by computing shortest paths, and hence they are suitable to be used in combination with speed-up techniques developed for road networks. In this paper, we focus on the dynamic behavior of graph-based models considering the case where transportation systems are subject to delays with respect to the given timetable. We make three contributions: (i) we give a simplified and optimized update routine for the well-known time-expanded model along with an engineered query algorithm; (ii) we propose a new graph-based model tailored for handling dynamic updates; (iii) we assess the effectiveness of the proposed models and algorithms by an experimental study, which shows that both models require negligible update time and a query time which is comparable to that required by some array-based models.
@InProceedings{cionini_et_al:OASIcs.ATMOS.2014.46, author = {Cionini, Alessio and D'Angelo, Gianlorenzo and D'Emidio, Mattia and Frigioni, Daniele and Giannakopoulou, Kalliopi and Paraskevopoulos, Andreas and Zaroliagis, Christos}, title = {{Engineering Graph-Based Models for Dynamic Timetable Information Systems}}, booktitle = {14th Workshop on Algorithmic Approaches for Transportation Modelling, Optimization, and Systems}, pages = {46--61}, series = {Open Access Series in Informatics (OASIcs)}, ISBN = {978-3-939897-75-0}, ISSN = {2190-6807}, year = {2014}, volume = {42}, editor = {Funke, Stefan and Mihal\'{a}k, Mat\'{u}s}, publisher = {Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik}, address = {Dagstuhl, Germany}, URL = {https://drops.dagstuhl.de/entities/document/10.4230/OASIcs.ATMOS.2014.46}, URN = {urn:nbn:de:0030-drops-47522}, doi = {10.4230/OASIcs.ATMOS.2014.46}, annote = {Keywords: Timetabling, dynamic updates, queries, shortest paths} }
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