ATMOS 2008 Abstracts Collection -- 8th Workshop on Algorithmic Approaches for Transportation Modeling, Optimization, and Systems

ATMOS 2008 - Abstracts Collection Selected Papers from the 8th Workshop on Algorithmic Approaches for Transportation Modeling, Optimization, and Systems Matteo Fischetti1 and Peter Widmayer2 University of Padova, IT and ETH Zürich, CH Abstract. Proceedings of the 8th Workshop on Algorithmic Approaches for Transportation Modeling, Optimization, and Systems, held on Septmeber 18 in Karlsruhe, Germany. ATMOS 2008 Preface  8th Workshop on Algorithmic Approaches for Transportation Modeling, Optimization, and Systems The 8th ATMOS workshop was held in Karlsruhe, September 18, 2008, within ALGO, a set of meetings related to algorithms. The series of ATMOS workshops, starting in Heraklion in 2001, continuing in Malaga in 2002, Budapest in 2003, Bergen in 2004, Palma de Mallorca in 2005, Zürich in 2006, and Sevilla in 2007 is by now an established series of meetings between algorithms researchers dealing with transportation problems, and practitioners, mainly from railways. Joint work of: Fischetti, Matteo; Widmayer, Peter Extended Abstract: http://drops.dagstuhl.de/opus/volltexte/2008/1593 Dynamic Algorithms for Recoverable Robustness Problems Recently, the recoverable robustness model has been introduced in the optimization area. This model allows to consider disruptions (input data changes) in a unied way, that is, during both the strategic planning phase and the operational phase. Although the model represents a signicant improvement, it has the following drawback: we are typically not facing only one disruption, but many of them might appear one after another. In this case, the solutions provided in the context of the recoverable robustness are not satisfying. In this paper we extend the concept of recoverable robustness to deal not only with one single recovery step, but with arbitrarily many recovery steps. To this aim, we introduce the notion of dynamic recoverable robustness problems. We apply the new model in the context of timetabling and delay management problems. We are interested in nding ecient dynamic robust algorithms for solving the timetabling problem and in evaluating the price of robustness of the proposed solutions. ATMOS 2008 8th Workshop on Algorithmic Approaches for Transportation Modeling, Optimization, and Systems http://drops.dagstuhl.de/opus/volltexte/2008/1592 2 M. Fischetti, P. Widmayer Robustness, optimization problems, dynamic algorithms, timetabling, delay management Joint work of: Cicerone, Serano; Di Stefano, Gabriele; Schachtebeck, Michael; Schöbel, Anita Full Paper: http://drops.dagstuhl.de/opus/volltexte/2008/1587 Keywords: Ecient On-Trip Timetable Information in the Presence of Delays The search for train connections in state-of-the-art commercial timetable information systems is based on a static schedule. Unfortunately, public transportation systems suer from delays for various reasons. Thus, dynamic changes of the planned schedule have to be taken into account. A system that has access to delay information of trains (and uses this information within search queries) can provide valid alternatives in case a train change breaks. Additionally, it can be used to actively guide passengers as these alternatives may be presented before the passenger is already stranded at a station due to a broken transfer. In this work we present an approach which takes a stream of delay information and schedule changes on short notice (partial train cancellations, extra trains) into account. Primary delays of trains may cause a cascade of so-called secondary delays of other trains which have to wait according to certain waiting policies between connecting trains. We introduce the concept of a dependency graph to eciently calculate and update all primary and secondary delays. This delay information is then incorporated into a time-expanded search graph which has to be updated dynamically. These update operations are quite complex, but turn out to be not time-critical in a fully realistic scenario. We nally present a case study with data provided by Deutsche Bahn AG showing that this approach has been successfully integrated into our multi-criteria timetable information system MOTIS and can handle massive delay data streams instantly. Keywords: Timetable information system, primary and secondary delays dependency graph, dynamic graph update Joint work of: Frede, Lennart; Müller-Hannemann, Matthias; Schnee, Mathias Full Paper: http://drops.dagstuhl.de/opus/volltexte/2008/1584 Engineering Time-Expanded Graphs for Faster Timetable Information We present an extension of the well-known time-expanded approach for timetable information. By remodeling unimportant stations, we are able to obtain faster query times with less space consumption than the original model. Moreover, we show that our extensions harmonize well with speed-up techniques whose adaption to timetable networks is more challenging than one might expect. ATMOS 2008 - 8th Workshop on Algorithmic Approaches for Transportation Modeling, Optimization, and Systems 3 Keywords: Timetable information, shortest path, modeling Joint work of: Full Paper: Delling, Daniel; Pajor, Thomas; Wagner, Dorothea http://drops.dagstuhl.de/opus/volltexte/2008/1582 Integrated Gate and Bus Assignment at Amsterdam Airport Schiphol At an airport a series of assignment problems need to be solved before aircraft can arrive and depart and passengers can embark and disembark. A lot of different parties are involved with this, each of which having to plan their own schedule. Two of the assignment problems that the 'Regie' at Amsterdam Airport Schiphol (AAS) is responsible for, are the gate assignment problem (i.e. where to place which aircraft) and the bus assignment problem (i.e. which bus will transport which passengers to or from the aircraft). Currently these two problems are solved in a sequential fashion, the output of the gate assignment problem is used as input for the bus assignment problem. We look at integrating these two sequential problems into one larger problem that considers both problems at the same time. This creates the possibility of using information regarding the bus assignment problem while solving the gate assignment problem. We developed a column generation algorithm for this problem and have implemented a prototype. To make the algorithm ecient we used a special technique called stabilized column generation and also column deletion. Computational experiments with real-life data from AAS indicate that our algorithm is able to compute a planning for one day at Schiphol in a reasonable time. Gate assignment, airports, integrated planning, column generation, integer linear programming Keywords: Joint work of: Full Paper: Diepen, Guido; van den Akker, Marjan; Hoogeveen, Han http://drops.dagstuhl.de/opus/volltexte/2008/1591 IP-based Techniques for Delay Management with Priority Decisions Delay management is an important issue in the daily operations of any railway company. The task (...truncated)