5,094 research outputs found
Evaluating the performance of an advanced train dispatching support system
No full textIn the last years, real-time railway traffic optimization experienced an increasing interest due to the expected growth of traffic and the limited possibilities of enhancing the infrastructure, which ask for a more efficient use of resources and the application of more advanced decision support tools. This paper presents a computerized train dispatching system, called ROMA (Railway traffic Optimization by Means of Alternative graphs), for supporting railway traffic controllers during operations. Innovative scheduling and rerouting algorithms have been developed in order to globally optimize disturbed railway traffic conditions. ROMA can anticipate the evolution of traffic, including the propagation of delays in a regional railway network, and can estimate the effects of different dispatching measures during a period of about 15 minutes ahead. Therefore, ROMA would enable traffic controllers to frequently perform incremental changes to the actual timetable to accommodate changes in traffic patterns due to disturbances, such as train delays and blocked tracks. An extensive computational study is carried out, based on a dispatching area of the Dutch railway network, to show the high potential of our train dispatching system as a support tool to improve punctuality
Network-Wide Public Transport Occupancy Prediction Framework with Multiple Line Interactions
No full textThis paper addresses the problem of predicting the occupancy of urban public transport vehicles with a network-wide framework where the effects of the interactions between multiple lines are jointly considered. In particular, we propose and compare several occupancy predictors, each of them differing in the amount of information used and in the prediction model adopted. We consider twoprediction models: a behavioral model that assumes an explicit relation between some observed variables and the occupancy, and a machine learning model based on the LightGBM algorithm. We evaluate the proposed network-wide prediction framework on two real-world case studies related to the public transport network of the Swiss city of Zurich. The results show that predicting the occupancy for a target line while simultaneously considering the other lines in the network allows significant improvements in the accuracy of the predictions, especially in the corridors served by different interacting lines. The described methodology could be used by public transport agencies to improve the accuracy of the crowding information provided to passengers and to increase the attractiveness of public transport systems
Assessment of advanced dispatching measures for recovering disrupted railway traffic situations
No full textISSN:0361-1981ISSN:2169-4052ISSN:2169-405
A multi-criteria decision support methodology for real-time train scheduling
Full text linkThis work addresses the real-time optimization of train scheduling decisions at a complex railway network during congested traffic situations. The problem of effectively managing train operations is particularly challenging, since it is necessary to incorporate the safety regulations into the optimization model and to consider key performance indicators. This paper deals with the development of a multi-criteria decision support methodology to help dispatchers in taking more informed decisions when dealing with real-time disturbances. Optimal train scheduling solutions are computed with high level precision in the modeling of the safety regulations and with consideration of state-of-the-art performance indicators. Mixed-integer linear programming formulations are proposed and solved via a commercial solver. For each problem instance, an iterative method is proposed to establish an efficient-inefficient classification of the best solutions provided by the formulations via a well-established non-parametric benchmarking technique: data envelopment analysis. Based on this classification, inefficient formulations are improved by the generation of additional linear constraints. Computational experiments are performed for practical-size instances from a Dutch railway network with mixed traffic and several disturbances. The method converges after a limited number of iterations, and returns a set of efficient solutions and the relative formulations
Rescheduling railway traffic taking into account minimization of passengers’ discomfort
No full textOptimization models for railway traffic rescheduling in the last decade tend to develop along two main streams. One the one hand, train scheduling models strives to incorporate any relevant detail of the railway infrastructure having an impact on the feasibility and quality of the solutions from the viewpoint of operations managers. On the other hand, delay management models focus on the impact of rescheduling decisions on the quality of service perceived by the passengers. Models in the first stream are mainly microscopic, while models in the second stream are mainly macroscopic. This paper aims at merging these two streams of research by developing microscopic passenger-centric models, solution algorithms and lower bounds. Fast iterative algorithms are proposed, based on a decomposition of the problem and on the exact resolution of the sub-problems. A new lower bound is proposed, consisting of the resolution of a set of min-cost flow problems with activation constraints. Computational experiments, based on a real-world Dutch railway network, show that good quality solutions and lower bounds can be found within a limited computation time
Dispatching and coordination in multi-area railway traffic management
No full textThis paper deals with the development of decision support systems for traffic management of large and busy railway networks in case of severe disturbances. Railway operators typically structure the control of complicated networks into the coordinated control of several local dispatching areas. A dispatcher takes rescheduling decisions on the trains running on its local area while a coordinator addresses global issues that may arise between areas. While several advanced train dispatching models and algorithms have been proposed to support the dispatchers' task, the coordination problem did not receive much attention in the literature on train scheduling. This paper presents new heuristic algorithms for both local dispatching and coordination and compares centralized and distributed procedures to support the task of dispatchers and coordinators. We adopt dispatching procedures driven by optimization algorithms and based on local or global information and decisions. Computational experiments on a Dutch railway network, actually controlled by ten dispatchers, assess the performance of the centralized and distributed procedures. Various traffic disturbances, including entrance delays and blocked tracks, are analyzed on various time horizons of traffic prediction. Results show that the new heuristics clearly improve the global performance of the network with respect to the state of the art. (C) 2013 Elsevier Ltd. All rights reserved
Reordering and local rerouting strategies to manage train traffic in real-time
No full textTraffic controllers regulate railway traffic by sequencing train movements and setting routes with the aim of
ensuring smooth train behaviour and limiting, as much as possible, train delays. In this paper, we describe the implementation of a real-time traffic management system, called ROMA (Railway traffic Optimization by Means of Alternative graphs), to support controllers in the everyday task of managing disturbances. We make
use of a branch-and-bound algorithm for sequencing train movements, while a local search algorithm is
developed for rerouting optimization purposes. The compound problem of routing and sequencing trains is
approached iteratively, computing an optimal train sequencing for given train routes and then improving this
solution by locally rerouting some trains. An extensive computational study is carried out, based on a dispatching area of the Dutch railway network. We study practical size instances, and include in the model important
operational constraints, including rolling stock and passenger connections. Different types of disturbances are
analysed, including train delays and blocked tracks. Comparison with common dispatching practice shows the
high potential of the system as an effective support tool to improve punctuality
Real-time conflict detection and resolution: global sequencing and local rerouting
No full textTraffic controllers regulate railway traffic sequencing train movements and setting routes with the aim of ensuring smooth train behaviour and limiting as much as possible
train delays. In this paper we describe the implementation of a real-time traffic management system, called ROMA (Railway traffic Optimization by Means of Alternative
graphs), to support controllers in the everyday task of managing disturbances. We make use of a branch and bound algorithm for sequencing train movements, while a local
search algorithm is developed for rerouting optimization purposes. The compound problem of routing and sequencing trains is approached iteratively computing an optimal train
sequencing for given train routes, and then improving this solution by locally rerouting some trains. An extensive computational study is carried out, based on a dispatching
area of the Dutch railway network. We study practical size instances, and include in the model important operational constraints, including rolling stock and passenger connections. Different types of disturbances are analysed, including train delays and blocked tracks. Comparison with common dispatching practice shows the high potential of the
system as an effective support tool to improve punctuality.
Coordination of scheduling decisions in the management of airport airspace and taxiway operations
No full textThis paper addresses the real-time problem of coordinating aircraft ground and air operations in an airport area. At a congested airport, airborne decisions are related to take-off and landing operations, while ground (taxiway) decisions consist of scheduling aircraft movements between the gates and the runways. Since the runways are the initial/terminal points of both decisions, coordinated actions have a great potential to improve the overall performance. However, in the traffic control practice the different decisions are taken by different controllers, at least in large airports. Weak coordination may result in long queues at the runways, with increasing aircraft delays and energy consumption. This paper investigates models, methods and policies for improving the coordination between taxiway scheduling and airborne scheduling. The performance of a solution is measured in terms of delay and travel time, the latter being related to the energy consumption of an aircraft. A microscopic mathematical formulation is adopted to achieve reliable solutions. Exact and heuristic methods have been analysed in combination with the different policies, based on practical-size instances from Amsterdam Schiphol airport, in the Netherlands. Computational experience shows that good quality solutions can be found within limited time, compatible with real-time operations.Transport Engineering and Logistic
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