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Intriguingly Simple and Fast Transit Routing
- In SEA, volume 7933 of LNCS
, 2013
"... Abstract. This paper studies the problem of computing optimal jour-neys in dynamic public transit networks. We introduce a novel algorithmic framework, called Connection Scan Algorithm (CSA), to compute jour-neys. It organizes data as a single array of connections, which it scans once per query. Des ..."
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Abstract. This paper studies the problem of computing optimal jour-neys in dynamic public transit networks. We introduce a novel algorithmic framework, called Connection Scan Algorithm (CSA), to compute jour-neys. It organizes data as a single array of connections, which it scans once per query. Despite its simplicity, our algorithm is very versatile. We use it to solve earliest arrival and multi-criteria profile queries. Moreover, we extend it to handle the minimum expected arrival time (MEAT) prob-lem, which incorporates stochastic delays on the vehicles and asks for a set of (alternative) journeys that in its entirety minimizes the user’s expected arrival time at the destination. Our experiments on the dense metropolitan network of London show that CSA computes MEAT queries, our most complex scenario, in 272ms on average. 1
Result Diversity for Multi-Modal Route Planning
- 13th Workshop on Algorithmic Approaches for Transportation Modelling, Optimization, and Systems, volume 33 of OpenAccess Series in Informatics (OASIcs), pages123–136, Dagstuhl
, 2013
"... We study multi-modal route planning allowing arbitrary (meaningful) combinations of public transportation, walking, and taking a car / taxi. In the straightforward model, the number of Pareto-optimal solutions explodes. It turns out that many of them are similar to each other or unreasonable. We int ..."
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We study multi-modal route planning allowing arbitrary (meaningful) combinations of public transportation, walking, and taking a car / taxi. In the straightforward model, the number of Pareto-optimal solutions explodes. It turns out that many of them are similar to each other or unreasonable. We introduce a new filtering procedure, Types aNd Thresholds (TNT), which leads to a small yet representative subset of the reasonable paths. We consider metropolitan areas like New York, where a fast computation of the paths is difficult. To reduce the high compu-tation times, optimality-preserving and heuristic approaches are introduced. We experimentally evaluate our approach with respect to result quality and query time. The experiments confirm that our result sets are indeed small (around 5 results per query) and representative (among the reasonable Pareto-optimal paths), and with average query times of about one second or less.
Computing Multimodal Journeys in Practice?
"... Abstract. We study the problem of finding multimodal journeys in transportation networks, including unrestricted walking, driving, cycling, and schedule-based public transportation. A natural solution to this problem is to use multicriteria search, but it tends to be slow and to produce too many jou ..."
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Abstract. We study the problem of finding multimodal journeys in transportation networks, including unrestricted walking, driving, cycling, and schedule-based public transportation. A natural solution to this problem is to use multicriteria search, but it tends to be slow and to produce too many journeys, several of which are of little value. We pro-pose algorithms to compute a full Pareto set and then score the solu-tions in a postprocessing step using techniques from fuzzy logic, quickly identifying the most significant journeys. We also propose several (still multicriteria) heuristics to find similar journeys much faster, making the approach practical even for large metropolitan areas. 1
Delay-Robustness of Transfer Patterns in Public Transportation Route Planning
- In 13th Work. on Algorithmic Approaches for Transportation Modelling, Optimization, and Systems (ATMOS
, 2013
"... Abstract Transfer pattern routing is a state-of-the-art speed-up technique for finding optimal paths which minimize multiple cost criteria in public transportation networks. It precomputes sequences of transfer stations along optimal paths. At query time, the optimal paths are searched among the st ..."
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Abstract Transfer pattern routing is a state-of-the-art speed-up technique for finding optimal paths which minimize multiple cost criteria in public transportation networks. It precomputes sequences of transfer stations along optimal paths. At query time, the optimal paths are searched among the stored transfer patterns, which allows for very fast response times even on very large networks. On the other hand, even a minor change to the timetables may affect many optimal paths, so that, in principle, a new computation of all optimal transfer patterns becomes necessary. In this paper, we examine the robustness of transfer pattern routing towards delay, which is the most common source of such updates. The intuition is that the deviating paths caused by typical updates are already covered by original transfer patterns. We perform experiments which show that the transfer patterns are remarkably robust even to large and many delays, which underlines the applicability and reliability of transfer pattern routing in realistic routing applications.
Route planning using Linked Open Data
"... Abstract. Intermodal route planners need to be provided with a lot of data from various sources: geographical data, speed limits, road blocks, time schedules, realtime vehicle locations, etc. These datasets need to be interoperable world-wide. Today, a lot of data integration needs to be done befor ..."
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Abstract. Intermodal route planners need to be provided with a lot of data from various sources: geographical data, speed limits, road blocks, time schedules, realtime vehicle locations, etc. These datasets need to be interoperable world-wide. Today, a lot of data integration needs to be done before this data can be be reused. Route planning becomes a data problem rather than a mathematical problem. Can the Web act as a global distributed dataspace for transport data? Could introducing Linked Open Data to this field make the data quality raise?
Intermodal public transit routing using Linked Connections
"... Abstract. Ever since public transit agencies have found their way to the Web, they inform travelers using route planning software made available on their website. These travelers also need to be informed about other modes of transport, for which they have to consult other websites, or for which the ..."
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Abstract. Ever since public transit agencies have found their way to the Web, they inform travelers using route planning software made available on their website. These travelers also need to be informed about other modes of transport, for which they have to consult other websites, or for which they have to ask the transit agency's server maintainer to implement new functionalities. In this demo, we introduce an affordable publishing method for transit data, called Linked Connections, that can be used for intermodal route planning, by allowing user agents to execute the route planning algorithm. We publish paged documents containing a stream of hops between transit stops sorted by departure time. Using these documents, clients are able to perform intermodal route planning in a reasonable time. Furthermore, such clients are fully in charge of the algorithm, and can now also route in different ways by integrating datasets of a user's choice. When visiting our demo, conference attendees will be able to calculate intermodal routes by querying the Web of data using their phone's browser, without expensive server infrastructure.
(Please request at least one week in advance).Access to Destinations: Annual Accessibility Measure for the Twin Cities Metropolitan Region Final Report Prepared by:
, 2012
"... This report documents the results of research conducted by the authors and does not necessarily represent the views or policies of the Minnesota Department of Transportation and/or the University of Minnesota. This report does not contain a standard or specified technique. The authors, the Minnesota ..."
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This report documents the results of research conducted by the authors and does not necessarily represent the views or policies of the Minnesota Department of Transportation and/or the University of Minnesota. This report does not contain a standard or specified technique. The authors, the Minnesota Department of Transportation, and the University of Minnesota Studies do not endorse products or manufacturers. Trade or manufacturers ’ names appear herein solely because they are considered
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"... We study the problem of computing best connections in pub-lic transit networks. A common approach models the net-work as a graph (Pyrga et al. 2008) on which it runs a short-est path algorithm (Dijkstra 1959). To enable interactive queries, a variety of speedup techniques exist that use a pre-proces ..."
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We study the problem of computing best connections in pub-lic transit networks. A common approach models the net-work as a graph (Pyrga et al. 2008) on which it runs a short-est path algorithm (Dijkstra 1959). To enable interactive queries, a variety of speedup techniques exist that use a pre-processing stage to accelerate queries (Delling et al. 2009; Bast et al. 2010). Unfortunately, developed with road net-works in mind, they fall short on public transit networks due to their different combinatorial structure (Bast 2009). Also, unlike in road networks, one is usually interested in reporting Pareto sets of journeys for several criteria, such as travel time and the number of transfers. While Dijkstra’s algorithm can be augmented (Pyrga et al. 2008), this in-creases running time even further (Berger et al. 2009; Disser,
