eng
Schloss Dagstuhl – Leibniz-Zentrum für Informatik
Open Access Series in Informatics
2190-6807
2011-09-19
20
0
0
10.4230/OASIcs.ATMOS.2011
article
OASIcs, Volume 20, ATMOS'11, Complete Volume
Caprara, Alberto
Kontogiannis, Spyros
OASIcs, Volume 20, ATMOS'11, Complete Volume
https://drops.dagstuhl.de/storage/01oasics/oasics-vol020-atmos2011/OASIcs.ATMOS.2011/OASIcs.ATMOS.2011.pdf
Analysis of Algorithms and Problem Complexity, Optimization, Graph Theory, Applications
eng
Schloss Dagstuhl – Leibniz-Zentrum für Informatik
Open Access Series in Informatics
2190-6807
2011-09-19
20
i
ix
10.4230/OASIcs.ATMOS.2011.i
article
Frontmatter, Table of Contents, Preface, Workshop Organization
Caprara, Alberto
Kontogiannis, Spyros
Frontmatter, Table of contents, Preface, Workshop Organization
https://drops.dagstuhl.de/storage/01oasics/oasics-vol020-atmos2011/OASIcs.ATMOS.2011.i/OASIcs.ATMOS.2011.i.pdf
Frontmatter
Table of contents
Preface
Workshop Organization
eng
Schloss Dagstuhl – Leibniz-Zentrum für Informatik
Open Access Series in Informatics
2190-6807
2011-09-19
20
1
14
10.4230/OASIcs.ATMOS.2011.1
article
Real-time traffic control in railway systems
Mannino, Carlo
Despite the constantly increasing demand of passengers and goods transport in Europe, the share of railway traffic is decreasing. One major reason appears to be congestion, which in turn results in frequent delays and in a general unreliability of the system. This fact has triggered the study of efficient ways to manage railway traffic, both off-line and real-time, by means of optimization and mathematical programming techniques. And yet, to our knowledge, there are only a few fully automated real-time traffic control systems which are actually in operation in the European railway system; in most cases such systems only control very simple lines and actually they only support the activity of human dispatchers. We describe here two recent optimization based applications to real-time traffic control which have actually been put into operation in the Italian railways. One such system has been able to fully control the trains in the terminal stations of Milano metro system. The other one will be fully operative by the end of 2012, when it will control the trains on several Italian single-track railways. Both systems heavily rely on mixed integer programming techniques to elaborate good quality timetables in real time.
https://drops.dagstuhl.de/storage/01oasics/oasics-vol020-atmos2011/OASIcs.ATMOS.2011.1/OASIcs.ATMOS.2011.1.pdf
Railway systems
traffic control
eng
Schloss Dagstuhl – Leibniz-Zentrum für Informatik
Open Access Series in Informatics
2190-6807
2011-09-19
20
15
26
10.4230/OASIcs.ATMOS.2011.15
article
A bilevel rescheduling framework for optimal inter-area train coordination
Corman, Francesco
D'Ariano, Andrea
Pacciarelli, Dario
Pranzo, Marco
Railway dispatchers reschedule trains in real-time in order to limit the propagation of disturbances and to regulate traffic in their respective dispatching areas by minimizing the deviation from the off-line timetable. However, the decisions taken in one area may influence the quality and even the feasibility of train schedules in the other areas. Regional control centers coordinate the dispatchers' work for multiple areas in order to regulate traffic at the global level and to avoid situations of global infeasibility. Differently from the dispatcher problem, the coordination activity of regional control centers is still underinvestigated, even if this activity is a key factor for effective traffic management.
This paper studies the problem of coordinating several dispatchers with the objective of driving their behavior towards globally optimal solutions. With our model, a coordinator may impose constraints at the border of each dispatching area. Each dispatcher must then schedule trains in its area by producing a locally feasible solution compliant with the border constraints imposed by the coordinator. The problem faced by the coordinator is therefore a bilevel programming problem in which the variables controlled by the coordinator are the border constraints. We demonstrate that the coordinator problem can be solved to optimality with a branch and bound procedure. The coordination algorithm has been tested on a large real railway network in the Netherlands with busy traffic conditions. Our experimental results show that a proven optimal solution is frequently found for various network divisions within computation times compatible with real-time operations.
https://drops.dagstuhl.de/storage/01oasics/oasics-vol020-atmos2011/OASIcs.ATMOS.2011.15/OASIcs.ATMOS.2011.15.pdf
Train Delay Minimization
Schedule Coordination
Bilevel Programming
eng
Schloss Dagstuhl – Leibniz-Zentrum für Informatik
Open Access Series in Informatics
2190-6807
2011-09-19
20
27
37
10.4230/OASIcs.ATMOS.2011.27
article
The Lockmaster's problem
Coene, Sofie
Spieksma, Frits C. R.
Inland waterways form a natural network that is an existing, congestion free infrastructure with capacity for more traffic. The European commission promotes the transportation of goods by ship as it is a reliable, efficient and environmental friendly way of transport. A bottleneck for transportation over water are the locks that manage the water level. The lockmaster's problem concerns the optimal strategy for operating such a lock. In the lockmaster's problem we are given a lock, a set of ships coming from downstream that want to go upstream, and another set of ships coming from upstream that want to go downstream. We are given the arrival times of the ships and a constant lockage time; the goal is to minimize total waiting time of the ships. In this paper a dynamic programming algorithm (DP) is proposed that solves the lockmaster's problem in polynomial time. We extend this DP to different generalizations that consider weights, water usage, capacity, and (a fixed number of) multiple chambers. Finally, we prove that the problem becomes strongly NP-hard when the number of chambers is part of the input.
https://drops.dagstuhl.de/storage/01oasics/oasics-vol020-atmos2011/OASIcs.ATMOS.2011.27/OASIcs.ATMOS.2011.27.pdf
lock scheduling
batch scheduling
dynamic programming
complexity
eng
Schloss Dagstuhl – Leibniz-Zentrum für Informatik
Open Access Series in Informatics
2190-6807
2011-09-19
20
38
51
10.4230/OASIcs.ATMOS.2011.38
article
Track Allocation in Freight-Train Classification with Mixed Tracks
Bohlin, Markus
Flier, Holger
Maue, Jens
Mihalák, Matús
We consider the process of forming outbound trains from cars of inbound trains at rail-freight hump yards. Given the arrival and departure times as well as the composition of the trains, we study the problem of allocating classification tracks to outbound trains such that every outbound train can be built on a separate classification track. We observe that the core problem can be formulated as a special list coloring problem in interval graphs, which is known to be NP-complete. We focus on an extension where individual cars of different trains can temporarily be stored on a special subset of the tracks. This problem induces several new variants of the list-coloring problem, in which the given intervals can be shortened by cutting off a prefix of the interval. We show that in case of uniform and sufficient track lengths, the corresponding coloring problem can be solved in polynomial time, if the goal is to minimize the total cost associated with cutting off prefixes of the intervals. Based on these results, we devise two heuristics as well as an integer program to tackle the problem.
As a case study, we consider a real-world problem instance from the Hallsberg Rangerbangard hump yard in Sweden. Planning over horizons of seven days, we obtain feasible solutions from the integer program in all scenarios, and from the heuristics in most scenarios.
https://drops.dagstuhl.de/storage/01oasics/oasics-vol020-atmos2011/OASIcs.ATMOS.2011.38/OASIcs.ATMOS.2011.38.pdf
algorithms
complexity
graph theory
railways
scheduling
shunting
train classification
train marshalling
transportation
eng
Schloss Dagstuhl – Leibniz-Zentrum für Informatik
Open Access Series in Informatics
2190-6807
2011-09-19
20
52
63
10.4230/OASIcs.ATMOS.2011.52
article
Faster Batched Shortest Paths in Road Networks
Delling, Daniel
Goldberg, Andrew V.
Werneck, Renato F.
We study the problem of computing batched shortest paths in road networks efficiently. Our focus is on computing paths from a single source to multiple targets (one-to-many queries). We perform a comprehensive experimental comparison of several approaches, including new ones. We conclude that a new extension of PHAST (a recent one-to-all algorithm), called RPHAST, has the best performance in most cases, often by orders of magnitude. When used to compute distance tables (many-to-many queries), RPHAST often outperforms all previous approaches.
https://drops.dagstuhl.de/storage/01oasics/oasics-vol020-atmos2011/OASIcs.ATMOS.2011.52/OASIcs.ATMOS.2011.52.pdf
shortest paths
contraction hierarchies
many-to-many
one-to-many
eng
Schloss Dagstuhl – Leibniz-Zentrum für Informatik
Open Access Series in Informatics
2190-6807
2011-09-19
20
64
75
10.4230/OASIcs.ATMOS.2011.64
article
UniALT for regular language contrained shortest paths on a multi-modal transportation network
Kirchler, Dominik
Liberti, Leo
Pajor, Thomas
Wolfler Calvo, Roberto
Shortest paths on road networks can be efficiently calculated using Dijkstra's algorithm (D). In addition to roads, multi-modal transportation networks include public transportation, bicycle lanes, etc. For paths on this type of network, further constraints, e.g., preferences in using certain modes of transportation, may arise. The regular language constrained shortest path problem deals with this kind of problem. It uses a regular language to model the constraints. The problem can be solved efficiently by using a generalization of Dijkstra's algorithm (D_RegLC). In this paper we propose an adaption of the speed-up technique uniALT, in order to accelerate D_RegLC. We call our algorithm SDALT. We provide experimental results on a realistic multi-modal public transportation network including time-dependent cost functions on arcs. The experiments show that our algorithm performs well, with speed-ups of a factor 2 to 20.
https://drops.dagstuhl.de/storage/01oasics/oasics-vol020-atmos2011/OASIcs.ATMOS.2011.64/OASIcs.ATMOS.2011.64.pdf
time-dependency
ALT
regular language
shortest path
multi-modal
eng
Schloss Dagstuhl – Leibniz-Zentrum für Informatik
Open Access Series in Informatics
2190-6807
2011-09-19
20
76
87
10.4230/OASIcs.ATMOS.2011.76
article
The Price of Robustness in Timetable Information
Goerigk, Marc
Knoth, Martin
Müller-Hannemann, Matthias
Schmidt, Marie
Schöbel, Anita
In timetable information in public transport the goal is to search for a good passenger's path between an origin and a destination. Usually, the travel time and the number of transfers shall be minimized. In this paper, we consider robust timetable information, i.e. we want to identify a path which will bring the passenger to the planned destination even in the case of delays. The classic notion of strict robustness leads to the problem of identifying those changing activities which will never break in any of the expected delay scenarios. We show that this is in general a strongly NP-hard problem. Therefore, we propose a conservative heuristic which identifies a large subset of these robust changing activities in polynomial time by dynamic programming and so allows us to find strictly robust paths efficiently. We also transfer the notion of light robustness, originally introduced for timetabling, to timetable information. In computational experiments we then study the price of strict and light robustness: How much longer is the travel time of a robust path than of a shortest one according to the published schedule? Based on the schedule of high-speed trains within Germany of 2011, we quantitatively explore the trade-off between the level of guaranteed robustness and the increase in travel time. Strict robustness turns out to be too conservative, while light robustness is promising: a modest level of guarantees is achievable at a reasonable price for the majority of passengers.
https://drops.dagstuhl.de/storage/01oasics/oasics-vol020-atmos2011/OASIcs.ATMOS.2011.76/OASIcs.ATMOS.2011.76.pdf
strict and light robustness
delay scenarios
experimental study
eng
Schloss Dagstuhl – Leibniz-Zentrum für Informatik
Open Access Series in Informatics
2190-6807
2011-09-19
20
88
99
10.4230/OASIcs.ATMOS.2011.88
article
Delay Management including Capacities of Stations
Dollevoet, Twan
Schmidt, Marie
Schöbel, Anita
The question of delay management (DM) is whether trains should wait for delayed feeder trains or should depart on time. Solutions to this problem strongly depend on the capacity constraints of the tracks making sure that no two trains can use the same piece of track at the same time. While these capacity constraints have been included in integer programming formulations for DM, the capacity constraints of the stations (only offering a limited number of platforms) have been neglected so far. This can lead to highly infeasible solutions. In order to overcome this problem we suggest two new formulations for DM both including the stations' capacities. We present numerical results showing that the assignment-based formulation is clearly superior to the packing formulation. We furthermore propose an iterative algorithm in which we improve the platform assignment with respect to the current delays of the trains at each station in each step. We will show that this subproblem asks for coloring the nodes of a graph with a given number of colors while minimizing the weight of the conflicts. We show that the graph to be colored is an interval graph and that the problem can be solved in polynomial time by presenting a totally unimodular IP formulation.
https://drops.dagstuhl.de/storage/01oasics/oasics-vol020-atmos2011/OASIcs.ATMOS.2011.88/OASIcs.ATMOS.2011.88.pdf
Delay management
station capacities
eng
Schloss Dagstuhl – Leibniz-Zentrum für Informatik
Open Access Series in Informatics
2190-6807
2011-09-19
20
100
111
10.4230/OASIcs.ATMOS.2011.100
article
Stochastic Delay Prediction in Large Train Networks
Berger, Annabell
Gebhardt, Andreas
Müller-Hannemann, Matthias
Ostrowski, Martin
In daily operation, railway traffic always deviates from the planned schedule to a certain extent. Primary initial delays of trains may cause a whole cascade of secondary delays of other trains over the entire network. In this paper, we propose a stochastic model for delay propagation and forecasts of arrival and departure events which is applicable to all kind of public transport (not only to railway traffic). Our model is fairly realistic, it includes general waiting policies (how long do trains wait for delayed feeder trains), it uses driving time profiles (discrete distributions) on travel arcs which depend on the departure time, and it incorporates the catch-up potential of buffer times on driving sections and train stops. The model is suited for an online scenario where a massive stream of update messages on the current status of trains arrives which has to be propagated through the whole network. Efficient stochastic propagation of delays has important applications in online timetable information, in delay management and train disposition, and in stability analysis of timetables.
The proposed approach has been implemented and evaluated on the German timetable of 2011 with waiting policies of Deutsche Bahn AG. A complete stochastic delay propagation for the whole German train network and a whole day can be performed in less than 14 seconds on a PC. We tested our propagation algorithm with artificial discrete travel time distributions which can be parametrized by the size of their fluctuations. Our forecasts are compared with real data. It turns out that stochastic propagation of delays is efficient enough to be applicable in practice, but the forecast quality requires further adjustments of our artificial travel time distributions to estimates from real data.
https://drops.dagstuhl.de/storage/01oasics/oasics-vol020-atmos2011/OASIcs.ATMOS.2011.100/OASIcs.ATMOS.2011.100.pdf
stochastic delay propagation
timetable information
delay management
train disposition
stability analysis
eng
Schloss Dagstuhl – Leibniz-Zentrum für Informatik
Open Access Series in Informatics
2190-6807
2011-09-19
20
112
121
10.4230/OASIcs.ATMOS.2011.112
article
Comparison of discrete and continuous models for the pooling problem
Alfaki, Mohammed
Haugland, Dag
The pooling problem is an important global optimization problem which is encountered in many industrial settings. It is traditionally modeled as a bilinear, nonconvex optimization problem, and solved by branch-and-bound algorithms where the subproblems are convex. In some industrial applications, for instance in pipeline transportation of natural gas, a different modeling approach is often made. Rather than defining it as a bilinear problem, the range of qualities is discretized, and the complicating constraints are replaced by linear ones involving integer variables. Consequently, the pooling problem is approximated by a mixed-integer programming problem. With a coarse discretization, this approach represents a saving in computational effort, but may also lead to less accurate modeling. Justified guidelines for choosing between a bilinear and a discrete model seem to be scarce in the pooling problem literature. In the present work, we study discretized versions of models that have been proved to work well when formulated as bilinear programs. Through extensive numerical experiments, we compare the discrete models to their continuous ancestors. In particular, we study how the level of discretization must be chosen if a discrete model is going to be competitive in both running time and accuracy.
https://drops.dagstuhl.de/storage/01oasics/oasics-vol020-atmos2011/OASIcs.ATMOS.2011.112/OASIcs.ATMOS.2011.112.pdf
Global Optimization
Industrial Optimization
Graphs and Networks
Pooling problem
eng
Schloss Dagstuhl – Leibniz-Zentrum für Informatik
Open Access Series in Informatics
2190-6807
2011-09-19
20
122
133
10.4230/OASIcs.ATMOS.2011.122
article
On the Smoothed Price of Anarchy of the Traffic Assignment Problem
Buriol, Luciana
Ritt, Marcus
Rodrigues, Felix
Schäfer, Guido
We study the effect of perturbations on the Price of Anarchy for the Traffic Assignment Problem. Adopting the smoothed analysis approach, we randomly perturb the latency functions of the given network and estimate the expected Price of Anarchy on the perturbed instances. We provide both theoretical and experimental results that show that the Smoothed Price of Anarchy is of the same order of magnitude as the original one.
https://drops.dagstuhl.de/storage/01oasics/oasics-vol020-atmos2011/OASIcs.ATMOS.2011.122/OASIcs.ATMOS.2011.122.pdf
Traffic Assignment Problem
Smoothed Analysis
Price of Anarchy
eng
Schloss Dagstuhl – Leibniz-Zentrum für Informatik
Open Access Series in Informatics
2190-6807
2011-09-19
20
134
145
10.4230/OASIcs.ATMOS.2011.134
article
On the Utilisation of Fuzzy Rule-Based Systems for Taxi Time Estimations at Airports
Chen, Jun
Ravizza, Stefan
Atkin, Jason A. D.
Stewart, Paul
The primary objective of this paper is to introduce Fuzzy Rule-Based Systems (FRBSs) as a relatively new technology into airport transportation research, with a special emphasis on ground movement operations. Hence, a Mamdani FRBS with the capability to learn from data has been adopted for taxi time estimations at Zurich Airport (ZRH). Linear regression is currently the dominating technique for such an estimation task due to its established nature, proven mathematical characteristics and straightforward explanatory ability. In this study, we demonstrate that FRBSs, although having a more complex structure, can offer more accurate estimations due to their proven properties as nonlinear universal approximators. Furthermore, such improvements in accuracy do not come at the cost of the model's interpretability. FRBSs can offer more explanations of the underlying behavior in different regions. Preliminary results on data for ZRH suggest that FRBSs are a valuable alternative to already established linear regression methods. FRBSs have great potential to be further seamlessly integrated into the taxiway routing and scheduling process due to the fact that more information is now available in the explanatory variable space.
https://drops.dagstuhl.de/storage/01oasics/oasics-vol020-atmos2011/OASIcs.ATMOS.2011.134/OASIcs.ATMOS.2011.134.pdf
Fuzzy rule-based system
Taxi time estimation
Airport ground movement
eng
Schloss Dagstuhl – Leibniz-Zentrum für Informatik
Open Access Series in Informatics
2190-6807
2011-09-19
20
146
155
10.4230/OASIcs.ATMOS.2011.146
article
A Hypergraph Model for Railway Vehicle Rotation Planning
Borndörfer, Ralf
Reuther, Markus
Schlechte, Thomas
Weider, Steffen
We propose a model for the integrated optimization of vehicle rotations and vehicle compositions in long distance railway passenger transport. The main contribution of the paper is a hypergraph model that is able to handle the challenging technical requirements as well as very general stipulations with respect to the "regularity" of a schedule. The hypergraph model directly generalizes network flow models, replacing arcs with hyperarcs. Although NP-hard in general, the model is computationally well-behaved in practice. High quality solutions can be produced in reasonable time using high performance Integer Programming techniques, in particular, column generation and rapid branching. We show that, in this way, large-scale real world instances of our cooperation partner DB Fernverkehr can be solved.
https://drops.dagstuhl.de/storage/01oasics/oasics-vol020-atmos2011/OASIcs.ATMOS.2011.146/OASIcs.ATMOS.2011.146.pdf
Rolling Stock Planning
Hypergraph Modeling
Integer Programming
Column Generation
Rapid Branching