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Experimental Study on Speed-Up Techniques for Timetable Information Systems
- PROCEEDINGS OF THE 7TH WORKSHOP ON ALGORITHMIC APPROACHES FOR TRANSPORTATION MODELING, OPTIMIZATION, AND SYSTEMS (ATMOS 2007
, 2007
"... During the last years, impressive speed-up techniques for DIJKSTRA’s algorithm have been developed. Unfortunately, recent research mainly focused on road networks. However, fast algorithms are also needed for other applications like timetable information systems. Even worse, the adaption of recentl ..."
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Cited by 18 (10 self)
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During the last years, impressive speed-up techniques for DIJKSTRA’s algorithm have been developed. Unfortunately, recent research mainly focused on road networks. However, fast algorithms are also needed for other applications like timetable information systems. Even worse, the adaption of recently developed techniques to timetable information is more complicated than expected. In this work, we check whether results from road networks are transferable to timetable information. To this end, we present an extensive experimental study of the most prominent speed-up techniques on different types of inputs. It turns out that recently developed techniques are much slower on graphs derived from timetable information than on road networks. In addition, we gain amazing insights into the behavior of speed-up techniques in general.
Engineering Time-Expanded Graphs for Faster Timetable Information
, 2009
"... 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 ..."
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Cited by 7 (4 self)
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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.
Efficient On-Trip Timetable Information in the Presence of Delays
"... Abstract. The search for train connections in state-of-the-art commercial timetable information systems is based on a static schedule. Unfortunately, public transportation systems suffer from delays for various reasons. Thus, dynamic changes of the planned schedule have to be taken into account. A s ..."
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Abstract. The search for train connections in state-of-the-art commercial timetable information systems is based on a static schedule. Unfortunately, public transportation systems suffer 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 efficiently 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 finally 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.
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"... Abstract—We are concerned with solving the K-earliest arrival problem on the timetable information-based public transportation systems. The problem is like this: given a departure time window at station A, find K best itineraries from station A to station B in terms of the earliest arrival time at s ..."
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Abstract—We are concerned with solving the K-earliest arrival problem on the timetable information-based public transportation systems. The problem is like this: given a departure time window at station A, find K best itineraries from station A to station B in terms of the earliest arrival time at station B. There are two typical models for the timetable information, the time-expanded and the time-dependent models. The K-earliest arrival problem can be solved on the time-expanded model by using the classical K-shortest paths algorithms for static networks. In this paper, we modified one of these algorithms proposed by Martins and Santos and applied it to the time-dependent model. The experimental results on the Chinese railway system show that the modified algorithm is nearly 3 times faster than its original version on the time-expanded model. Index Terms—timetable information, time-expanded model, time-dependent model, K-earliest arrival itineraries. I.