Search

With the rise of smart cities in the near future, it will be possible to collect relevant data from passengers in order to improve the quality of transport services. In this paper, a mathematical model and algorithm are developed to plan the trips of the buses in a demand-responsive feeder service. A feeder service transports passengers from a low-demand area, like a sub-urban area, to a transportation hub, like a city center. The feeder service modeled in this paper considers two sets of bus stops: mandatory stops and optional stops. Mandatory stops are always visited by a bus, while optional stops are only visited when a client nearby makes a request for transportation. Passengers are assigned to a bus stop within walking distance. This in turn, gives the service both flexibility through the changing timetables and routes of the buses and some predictability due to the mandatory stops. To optimize the performance of the service, mathematical modeling techniques to improve the model's runtime are developed. It is concluded that a combination of column generation and the separation of sub-tour elimination constraints decreases the computing time of small and midsize instances significantly. ispartof: Networks vol:80 issue:3 pages:274-296 status: Published online

ispartof: Journal of Open Source Software vol:7 issue:77 status: published

Urban transportation contributes significantly to CO2 emissions. Public transport systems are a good strategy to reduce these, but the emissions generated by public transport vehicles should not be neglected during the design of the service. The Transit Network Design and Frequency Setting Problem (TNDFSP) has usually been addressed considering only the passengers’ and the operator’s point of view. However, we show it is worthwhile to consider also the emissions already during this planning phase. This paper proposes a memetic algorithm to address the bi-objective TNDFSP where both the total travel time and the CO2 emissions are minimized. The analysis considers a heterogeneous fleet, meaning that buses of different sizes and technologies can be assigned under a budget constraint. The results on benchmark instances show that the proposed memetic algorithm performs as well as state-of-the-art algorithms where CO2 emissions are not considered. In addition, several experiments are carried out to observe the effect of incorporating emissions and heterogeneous fleet into the model. The heterogeneous fleet allows reducing travel times and emissions at the same time, compared to solutions without a heterogeneous fleet. Moreover, the explicit minimization of CO2 emissions within a bi-objective framework allows illustrating the trade-off between both objectives. Reductions of about 30% in the emissions can be achieved by increasing the travel time only 1%, while the costs for the operator remain the same. This clearly demonstrates the benefits of considering both the CO2 emissions and a heterogeneous fleet during the design stage of public transport systems. ispartof: European Journal Of Operational Research vol:282 issue:2 pages:580-592 status: published

This paper introduces an efficient algorithm for the bike request scheduling problem (BRSP). The BRSP is built around the concept of request, defined as the pickup or dropoff of a number of identical items (bikes) at a specific station, within a certain time window, and with a certain priority. The aim of the BRSP is to sequence requests on (and hence determine the routes of) a set of vehicles, in such a way that the sum of the priorities of the executed requests is maximized, all time windows are respected, and the capacity of the vehicles is not exceeded. The generation of the set of requests is explicitly not a part of the problem definition of the BRSP. The primary application of the BRSP, from which it derives its name, is to determine the routes of a set of repositioning vehicles in a bike sharing system, although other applications exist. The algorithm introduced in this paper is based on a set of related GRASP+VND (greedy randomized adaptive search procedure followed by variable neighborhood descent) operators embedded in a LNS (large neighborhood search) framework. Since this paper presents the first heuristic for the BRSP, a computational comparison to existing approaches is not possible. We therefore compare the solutions found by our LNS heuristic to those found by an exact solver (Gurobi). These experiments confirm that the proposed algorithm scales to realistic dimensions and is able to find near-optimal solutions in seconds. ispartof: International Transactions In Operational Research vol:27 issue:6 pages:2695-2714 status: published

We present a train platforming & routing expert system solving stations in seconds.It maximises the number of trains platformable and routable without conflicts.It also reports all conflicts existing in manual platforming plans.It is integrated in the Infrabel tool flow and works for all Belgian stations.Platforming planning is sped up & less error prone compared to current practice. Automatically generating train to platform assignments has been an active research area for some time, but systems implementing this research are still not readily available to practitioners. However, now, our train platforming model has been implemented as the tool Leopard inside Infrabel, the Belgian railway infrastructure manager. In practice, initial macroscopic timetables are often not yet feasible inside stations on the microscopic level. This means that a platforming tool must be able to handle cases where not all trains can be platformed or routed. Our model provides a platforming and routing plan for as many trains as possible and puts the remaining trains on a fictive platform. Contrary to the manually made platforming plans, the optimised platforming plans have no platform conflicts nor routing conflicts. Our model assigns as much trains as possible, given the timetable and the available infrastructure. Our tool can solve the platforming problems for all 530 stations in Belgium together in about 10 min. This means (i) it saves many man months of planning time compared to the still common manual practice to platforming and (ii) it achieves higher quality results leading to significantly less in-station train delays in practice.

Automatically generating timetables has been an active research area for some time, but the application of this research in practice has been limited. We believe this is due to two reasons. Firstly, some of the models in the literature impose artificial upper bounds on time supplements. This causes a high risk of generating infeasibilities. Secondly, some models that leave out these upper bounds often generate solutions that contain some very large time supplements because these supplements are not penalised in the objective function. The reason is that these objective functions often do not completely correspond to the true goal of a timetable. We solve both problems by minimising our objective function: total passenger travel time, expected in practice. Since this function evaluates and indirectly steers all time related decision variables in the system, we do not need to further restrict the ranges of any of these variables. As a result, our model does not suffer from infeasibilities generated by such artificial upper bounds for supplements. Furthermore, some measures are taken to significantly speed up the solver times of our model. These combined features result in our model being solved more quickly than previous models. As a result, our method can be used for timetabling in practice. We demonstrate our claims by optimising, in about two hours only, the timetable of all 196 hourly passenger trains in Belgium. Assuming primary delay-distributions with an average of 2% on the minima of each activity, the optimised timetable reduces expected passenger time in practice, as evaluated on the macroscopic level, by 3.8% during peak hours. This paper demonstrates that we added two important missing steps to make cyclic timetabling for passengers really useable in practice: (i) the addition of the objective function of expected passenger time in practice and (ii) the reduction of computation time by addition of well chosen additional constraints. publisher: Elsevier articletitle: Reducing the passenger travel time in practice by the automated construction of a robust railway timetable journaltitle: Transportation Research Part B: Methodological articlelink: http://dx.doi.org/10.1016/j.trb.2015.12.007 content_type: article copyright: Copyright © 2015 Elsevier Ltd. All rights reserved. ispartof: Transportation Research Part B vol:84 issue:84 pages:124-156 status: published

In real-time, dispatchers have the challenging task to perform railway traffic management. The goal is to update the timetable in order to reduce delays in case of unexpected events, by means of rescheduling or rerouting some of the trains. In order to support them in making decisions, a Traffic Management System (TMS) is required that is capable of predicting train movements, detecting potential conflicts and deciding on how to prevent these conflicts. A conflict occurs when two trains require the same part of the infrastructure at the same time. However, for dispatchers it is almost impossible to anticipate the impact of their preventing actions on the entire network. This paper therefore examines the dynamic impact zone created and used in a retiming/reordering heuristic. This heuristic is part of a conflict prevention strategy (CPS) aimed at assisting dispatchers by considering the relevant part of the network and the traffic when preventing conflicts. The CPS is extended such that also passenger delays and cancellations of passenger trains can be considered. This CPS is validated on a large study area of the Belgian network. The proposed CPS outperforms FCFS by, on average, 41 % in secondary delays and 33 % in passenger delays while delivering solutions in 2.1 seconds on average and in 12.3 seconds at maximum. ispartof: Proceedings of the Conference on Advanced Systems in Public Transport (CASPT 2018) ispartof: Conference on Advanced Systems in Public Transport (CASPT 2018) location:Brisbane, Australia date:23 Jul - 25 Jul 2018 status: published

© 2018 Elsevier Ltd In a railway system, a conflict occurs when two trains require the same part of the infrastructure at the same time. Currently, such conflicts are typically resolved manually by experienced dispatchers. However, it is impossible for them to fully anticipate the impact of their actions on the entire network. This paper proposes a conflict prevention strategy which focuses only on the relevant part of the network and traffic and, consequently, proposes a solution for that part only. The proposed strategy first looks for possible rerouting options by using an optimization model. If no solution is found, a solution based on delaying one of the trains is required. This retiming/reordering heuristic uses information from an offline calculation, for determining related conflicts that frequently occur. In this way, a so-called dynamic impact zone is created online for each conflict. When deciding which train to delay, the potential conflicts and the incurred delays of all trains in this dynamic impact zone are taken into account. The performance of this new Conflict Prevention Strategy is compared to a common dispatching strategy, other heuristics, and an exact method. Extensive experiments on a large part of the Belgian railway network show that by considering this dynamic impact zone the total delay can be decreased by at least 67% compared to the basic First Come, First Served decision rule. Moreover, the dynamic impact zone has a reasonable size and scales well to large networks as only the relevant conflicts and their expected consequences are considered. This makes our Dynamic Impact Zone heuristic very fast. The computation time for returning a resolution to a conflict with the proposed conflict prevention strategy is, for 95% of the conflicts, less than two seconds, and at most 26 s, including the creation of the dynamic impact zone of the conflict. ispartof: Transportation Research Part B vol:111 issue:111 pages:39-59 status: published

Delays and unreliable travel times are daily practice and unavoidable in public transport. Furthermore, manual decisions are still omnipresent in planning processes and real time dispatching. Nevertheless, the planning of public transport affects the performance and the popularity of these transport modes and the sustainability of the transport system as a whole. Therefore, investigating how public transport can benefit from decision support to improve the planning seems a promising direction for future research. This dissertation focuses on automatically developing timetables, routing plans and line plans for railway bottlenecks, such as the Brussels railway area (Belgium) and the Copenhagen S-tog network (Denmark). The connecting thread throughout this dissertation is providing a better service to passengers. Therefore passenger robustness is optimized, or in other words, the total travel time in practice of all passengers, in case of frequently occurring small delays, is minimized. Delay propagation from one train to another, which leads to unreliability and a lengthening of the passenger travel times, negatively affects this passenger robustness. Spreading the trains in time and space and including appropriate supplements in the timetable are solutions against delay propagation. This dissertation presents several timetabling methods that incorporate these solutions against delay propagation in an intelligent way. Furthermore, these timetabling methods are either integrated with a routing model or with a line planning model. Both a timetabling method to construct a passenger robust timetable from scratch and a method to improve the passenger robustness of an existing schedule are provided. All the methods are validated on real world case studies under varying circumstances. The computational results show that the developed methods are worthwhile to implement in practice. First because these methods allow to use the limited infrastructure in railway bottlenecks more efficiently, but even more so since simulation shows that these methods provide a much better service to the passengers than current practice. This state-of-the-art research is ready to be implemented in practice by railway companies, if they want to improve the service they offer to the passengers. The best timetable and routing plan for Brussels, developed from scratch with the methods presented in this dissertation, improve the passenger robustness up to 17% compared to the Belgian railway infrastructure manager Infrabel and up to 8% compared to the best timetable and routing plan from the literature. For the DSB S-tog network of Copenhagen, the integrated method for line planning and timetabling constructs line plans and timetables from scratch for which the weighted sum of operator and passenger cost is close to the optimal weighted sum of these costs. Moreover, the passenger robustness highly improves compared to the initial line plans and timetables in eight out of the ten studied cases. Preface i Abstract v Contents ix List of Figures xv List of Tables xxi 1 Introduction 1 1.1 Research goals . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 1.2 Scope of the thesis . . . . . . . . . . . . . . . . . . . . . . . . . 3 1.3 Contributions of the thesis . . . . . . . . . . . . . . . . . . . . . 5 1.4 Practical relevance of the thesis . . . . . . . . . . . . . . . . . . 7 1.5 Outline . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 2 State of the art 11 2.1 Definitions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11 2.1.1 How is a railway network built up? . . . . . . . . . . . . 12 2.1.2 How does a train drive through a railway network? . . . 16 2.1.3 How to plan a railway system? . . . . . . . . . . . . . . 20 2.2 Robustness in railway planning . . . . . . . . . . . . . . . . . . 29 2.3 Railway planning levels . . . . . . . . . . . . . . . . . . . . . . 36 2.3.1 Railway Routing . . . . . . . . . . . . . . . . . . . . . . 37 2.3.2 Timetabling . . . . . . . . . . . . . . . . . . . . . . . . . 37 2.3.3 Line planning . . . . . . . . . . . . . . . . . . . . . . . . 40 2.3.4 Integrated methods . . . . . . . . . . . . . . . . . . . . . 43 2.4 Conclusion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48 3 Improving passenger robustness on the tactical level 49 3.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50 3.2 Approach of Dewilde . . . . . . . . . . . . . . . . . . . . . . . . 50 3.2.1 Objective function . . . . . . . . . . . . . . . . . . . . . 51 3.2.2 Routing module . . . . . . . . . . . . . . . . . . . . . . 53 3.2.3 Timetabling module . . . . . . . . . . . . . . . . . . . . 55 3.2.4 Platforming module . . . . . . . . . . . . . . . . . . . . 55 3.2.5 Interaction between the modules . . . . . . . . . . . . . 56 3.3 Introducing passenger numbers . . . . . . . . . . . . . . . . . . 57 3.3.1 Implementation . . . . . . . . . . . . . . . . . . . . . . . 57 3.4 Introducing recurring delays . . . . . . . . . . . . . . . . . . . . 60 3.4.1 Implementation . . . . . . . . . . . . . . . . . . . . . . . 61 3.5 Simulation tool . . . . . . . . . . . . . . . . . . . . . . . . . . . 63 3.6 Case study . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 65 3.6.1 Network . . . . . . . . . . . . . . . . . . . . . . . . . . . 65 3.6.2 Line plan . . . . . . . . . . . . . . . . . . . . . . . . . . 66 3.6.3 Blocking times . . . . . . . . . . . . . . . . . . . . . . . 68 3.6.4 Generalizability . . . . . . . . . . . . . . . . . . . . . . . 69 3.6.5 Delay scenario . . . . . . . . . . . . . . . . . . . . . . . 70 3.7 Results . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 71 3.8 Conclusion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 73 3.9 Future research . . . . . . . . . . . . . . . . . . . . . . . . . . . 73 4 Robust routing and timetabling in complex railway stations 75 4.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 76 4.2 Methodology . . . . . . . . . . . . . . . . . . . . . . . . . . . . 78 4.2.1 Input . . . . . . . . . . . . . . . . . . . . . . . . . . . . 79 4.2.2 Output . . . . . . . . . . . . . . . . . . . . . . . . . . . 79 4.2.3 Routing model . . . . . . . . . . . . . . . . . . . . . . . 79 4.2.4 Timetabling model . . . . . . . . . . . . . . . . . . . . . 83 4.2.5 Small case study example . . . . . . . . . . . . . . . . . 90 4.3 Case study . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 93 4.4 Additional and alternative constraints for routing and timetabling models . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 94 4.4.1 Flow conservation constraints to speed up the routing model . . . . . . . . . . . . . . . . . . . . . . . . . . . . 94 4.4.2 Constraints to speed up the timetabling model . . . . . 96 4.4.3 Splitting, coupling and re-usage of trains in routing and timetabling models . . . . . . . . . . . . . . . . . . . . . 96 4.4.4 Passenger transfers in routing and timetabling models . 98 4.5 Results of the routing and the timetabling model . . . . . . . . 99 4.5.1 Routing results . . . . . . . . . . . . . . . . . . . . . . . 99 4.5.2 Delay scenario . . . . . . . . . . . . . . . . . . . . . . . 102 4.5.3 Timetabling and simulation results . . . . . . . . . . . . 102 4.6 Extended approach . . . . . . . . . . . . . . . . . . . . . . . . . 105 4.6.1 Input . . . . . . . . . . . . . . . . . . . . . . . . . . . . 105 4.6.2 Output . . . . . . . . . . . . . . . . . . . . . . . . . . . 106 4.6.3 Algorithm . . . . . . . . . . . . . . . . . . . . . . . . . . 107 4.7 Case study of the extended approach . . . . . . . . . . . . . . . 113 4.8 Results of the extended approach . . . . . . . . . . . . . . . . . 114 4.8.1 Results for limited train occupation . . . . . . . . . . . 114 4.8.2 Results for dense train occupation . . . . . . . . . . . . 116 4.8.3 Discussion . . . . . . . . . . . . . . . . . . . . . . . . . . 120 4.9 Conclusion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 121 4.10 Future research . . . . . . . . . . . . . . . . . . . . . . . . . . . 121 4.11 Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . . . 122 5 Integrating robust timetabling in line plan optimization 123 5.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 124 5.2 Timetable-infeasibility . . . . . . . . . . . . . . . . . . . . . . . 125 5.2.1 Line infeasibility . . . . . . . . . . . . . . . . . . . . . . 126 5.2.2 Frequency combination infeasibility . . . . . . . . . . . . 128 5.3 Methodology . . . . . . . . . . . . . . . . . . . . . . . . . . . . 135 5.3.1 Line planning module . . . . . . . . . . . . . . . . . . . 136 5.3.2 Timetabling module . . . . . . . . . . . . . . . . . . . . 143 5.3.3 Integrated approach . . . . . . . . . . . . . . . . . . . . 146 5.4 Case study . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 150 5.5 Results and discussion . . . . . . . . . . . . . . . . . . . . . . . 153 5.5.1 Results for ten line plans . . . . . . . . . . . . . . . . . 154 5.5.2 Illustration . . . . . . . . . . . . . . . . . . . . . . . . . 159 5.5.3 Limited shunt capacity . . . . . . . . . . . . . . . . . . . 165 5.6 Conclusion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 168 5.7 Future research . . . . . . . . . . . . . . . . . . . . . . . . . . . 168 5.8 Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . . . 169 6 Conclusion and future research 171 6.1 Conclusion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 171 6.2 Future research . . . . . . . . . . . . . . . . . . . . . . . . . . . 175 6.2.1 More degrees of freedom in timetabling . . . . . . . . . 175 6.2.2 Fast heuristic for timetabling . . . . . . . . . . . . . . . 177 6.2.3 Global optimum for line planning and timetabling . . . 177 6.3 Future work to bring this research into practice . . . . . . . . . 178 A Appendix 181 A.1 Deadlocks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 181 A.1.1 Strategies . . . . . . . . . . . . . . . . . . . . . . . . . . 181 A.1.2 Results . . . . . . . . . . . . . . . . . . . . . . . . . . . 182 A.1.3 Conclusion and future work . . . . . . . . . . . . . . . . 187 A.2 Passenger graph . . . . . . . . . . . . . . . . . . . . . . . . . . 189 A.3 List of symbols . . . . . . . . . . . . . . . . . . . . . . . . . . . 191 A.3.1 Symbols of Chapter 3 . . . . . . . . . . . . . . . . . . . 191 A.3.2 Symbols of Chapter 4 . . . . . . . . . . . . . . . . . . . 192 A.3.3 Symbols of Chapter 5 . . . . . . . . . . . . . . . . . . . 194 Bibliography 197 Curriculum vitae 207 Publications 209 nrpages: 242 status: published

This paper proposes an iterative approach to construct a passenger robust railway routing plan and timetable from scratch that also takes supplement and buffer time allocation into account on the signaling level. Each iteration is based on four pillars, which are subsequently executed. First a routing plan that optimizes infrastructure usage is constructed. Secondly, a timetable is constructed that optimizes buffer times between trains while taking passenger numbers into account. Thirdly, simulation is used to evaluate the passenger robustness of the routing plan and the timetable. Finally, the simulation outcome is used to make a new supplement assignment for the next iteration. The algorithm is tested on a case study for the complex station area of Brussels (Belgium). The resulting timetable and routing plan are much more passenger robust than the existing combinations of timetables and routing plans for this case, developed during research or implemented in practice. no ISSN ispartof: pages:190-208 ispartof: Proceedings of 7th International Seminar on Railway Operations Modelling and Analysis (IAROR) vol:2017 pages:190-208 ispartof: RailLille2017 location:Lille, France date:4 Apr - 7 Apr 2017 status: published

In nearly saturated station areas the limited capacity is one of the main reasons of delay propagation. Spreading the trains well in time and space in these areas has a big impact on the passenger robustness, i.e. the total travel time in practice of all passengers in the railway network in case of frequently occurring small delays. We focus on improving the performance in the bottleneck of the network in order to improve the performance of the whole railway network. This paper proposes a method that builds from scratch a routing plan and a cyclic timetable that optimizes the infrastructure occupation and the passenger robustness. An integer linear routing model assigns, without considering a timetable, every train to a route such that the maximal node usage is minimized and that the number of times that each node is used, is quadratically penalized. Thereafter, a mixed integer linear timetabling model assigns to each train the blocking times at which the nodes on its route, assigned by the routing model, are reserved and released. Different from other approaches is that we focus on the occupation of the railway infrastructure before constructing the timetable. The approach is validated on the complex railway station area of Brussels (Belgium). Our routing plan and timetable from scratch improve the passenger robustness up to 11% compared to a reference timetable and routing plan composed by the Belgian railway infrastructure manager Infrabel and by up to 2% compared to a reference timetable and routing plan from literature. ispartof: Transportation Research Part B vol:101 pages:228-244 status: published

We propose a heuristic algorithm to build a railway line plan from scratch that minimizes passenger travel time and operator cost and for which a feasible and robust timetable exists. A line planning module and a timetabling module work iteratively and interactively. The line planning module creates an initial line plan. The timetabling module evaluates the line plan and identifies a critical line based on minimum buffer times between train pairs. The line planning module proposes a new line plan in which the time length of the critical line is modified in order to provide more flexibility in the schedule. This flexibility is used during timetabling to improve the robustness of the railway system. The algorithm is validated on the DSB S-tog network of Copenhagen, which is a high frequency railway system, where overtakings are not allowed. This network has a rather simple structure, but is constrained by limited shunt capacity. While the operator and passenger cost remain close to those of the initially and (for these costs) optimally built line plan, the timetable corresponding to the finally developed robust line plan significantly improves the minimum buffer time, and thus the robustness, in eight out of ten studied cases. publisher: Elsevier articletitle: Integrating robust timetabling in line plan optimization for railway systems journaltitle: Transportation Research Part C: Emerging Technologies articlelink: http://dx.doi.org/10.1016/j.trc.2017.01.015 content_type: article copyright: © 2017 Elsevier Ltd. All rights reserved. ispartof: Transportation Research C, Emerging Technologies vol:77 pages:134-160 status: published

Though timetabling can account for some possible delays, in practice, external events still regularly lead to delays. Once trains are deviating from their schedule, conflicts can occur. A conflict implies that (at least) two trains require the same part of the infrastructure at the same time. Conflicts need to be resolved quickly in a way that disturbs the system as little as possible. Therefore, the impact on the whole network should be taken into account when solving conflicts. This paper discusses a heuristic conflict prevention technique capable of solving multiple conflicts together by reordering, retiming and locally rerouting trains. Based on a close-to-practice simulation tool where a simplified prediction horizon up to 10 minutes is considered, this technique is compared to FCFS. Results show significant improvements when comparing to FCFS. ispartof: pages:585-606 ispartof: Proceedings of 7th International Seminar on Railway Operations Modelling and Analysis (IAROR) vol:2017 pages:585-606 ispartof: RailLille2017 location:Lille, France date:4 Apr - 7 Apr 2017 status: published

Planned infrastructure works reduce the available capacity of a railway system and make it more vulnerable to conflicts and delay propagation. The starting point of this paper is a published timetable that needs to be adapted due to the temporary unavailability of some resources. Since the timetable is in operation, changed arrival or departure times and cancelations have an impact on the passengers who need to adapt their travel behavior. In the light of passenger service, a trade-off is made between these inconveniences and the delays that occur in practice due to the reduced capacity. Taking the robustness of the adapted railway timetable into account is a new approach to rescheduling in case of a planned infrastructure unavailability. In this paper, an algorithm that adjusts the train routing and the train schedule to the planned maintenance interventions and keeps the level of passenger service as high as possible is presented. To avoid large inconveniences, the developed algorithm tries to minimize the number of cancelations. Computational results show that by allowing small modifications to the routing and the timetable, the robustness of the resulting solution can improve by more than 10 percent and only few trains need to be canceled. publisher: Elsevier articletitle: An iterative approach for reducing the impact of infrastructure maintenance on the performance of railway systems journaltitle: European Journal of Operational Research articlelink: http://dx.doi.org/10.1016/j.ejor.2015.12.037 content_type: article copyright: Copyright © 2015 Elsevier B.V. All rights reserved. ispartof: European Journal of Operational Research vol:252 issue:1 pages:39-53 status: published

ispartof: Proceedings of the 9th Triennial Symposium on Transportation Analysis (TRISTAN) ispartof: Triennial Symposium on Transportation Analysis location:Oranjestad, Aruba date:12 Jun - 17 Jun 2016 status: published

In this paper we study the impact of the `turn conditions' in end stations on the performance of a line plan. If trains have to turn on their platform in an end station, the yoccupy the platform for several minutes. A more preferred option, from a timetabling point of view, would be that a train disappears from the platform in its end station after dwelling and only appears again when departing for a subsequent trip. In this case, the train will not interfere with other trains that dwell on the platform during the time between these events. However, this option is only possible if the train can stay in a exible and large enough shunt. Starting from a given line plan, we compare two timetables, one where trains have to turn on their platform and one where trains can turn in a shunt. We evaluate the impact on the performance of the line plan by its feasibility for timetabling,the minimum overall buffer time between trains, the sum of the buffer times and the buffer times in individual stations. A case study on the DSB S-tog in Copenhagen (Denmark) is performed.

The two topics of this thesis are macroscopic railway timetabling and station platforming and routing. These problems are challenges that are faced by all railway infrastructure companies. This thesis was carried out in cooperation with Infrabel, the Belgian railway infrastructure manager. (1) Macroscopic Cyclic Timetabling of Entire Countries In the macroscopic Train Timetabling Problem (TTP), the goal is to obtain, for each train and for each station it visits, an arrival and a departure time. Sufficient time should be provided for trains to ride from one station to the next. In stations, trains that stop should be allowed a minimal stop time, so that passengers can board, transfer or leave. Of course trains cannot collide on the same track and should even be separated by typically 3 minutes for safety reasons. No commercial software tools exist yet that automatically solve this problem. Over the last decennia, research at universities has led to automatically constructed ’draft’ timetables for the Netherlands, but these timetables still lack robustness against small recurrent delays. A timetable for the 37 trains of the Berlin underground was also constructed automatically, but also lacks robustness. For Belgium, about 200 hourly trains have to be planned, but Infrabel additionally requires that the timetable implies minimal passenger travel time in practice. This implies it will be robust. This was a new modelling and computational challenge. This time, which has to be minimised, includes journey time and small recurrent delays. In our latest paper, we also include excess journey time, which is the sum of waiting time at departure and at arrival. We are able to generate a timetable for all 196 hourly Belgian passenger trains from the 2013 timetable in a computation time of about 2 hours. Assuming common delays, the reduction of expected passenger time is 3.8% and the average missed transfer probability goes down from more than 10% in the original timetable to less than 3% in our timetable. Additionally, we also optimised the Danish timetable with 88 trains in about one hour, with a reduction of 2.9% of expected passenger time and reduced percentages for the probability of missing a transfer that are similar to the Belgian case. (2) Station Train Platforming and Routing For the problem of station platforming and routing, the arrival and departure times of trains are considered as given by the timetable. The sequential planning of the timetable and then station platforming and routing corresponds to the process currently used at Infrabel and almost all other railway companies. The challenge is then, to assign, per station, a platform track to each train such that no two trains are using the same infrastructure element at any time. This Train Platforming Problem (TPP) has been intensively studied and solved during the last decennia. Computation times are of the order of seconds per station. However, realisation of these automated methods at railway companies or into commercial tools for the railway industry has been limited. We solve this by developing and integrating a platforming tool at Infrabel. This tool produces a picture showing the current - manually made - platforming plan and indicates any conflict between any train pairs in the station area. We then generate an assignment without conflicts, of as many trains to platforms as possible. Sometimes, not all trains can be assigned to platform tracks and only a partial solution is given. This means that in practice, some trains cannot be assigned or otherwise the arrival and/or departure times have to be adapted manually. In the last case the macroscopic timetable also will have to be changed again. We also produce a picture of our optimised assignment which consistently shows that indeed, in our solution, there is no single conflict left. We are able to automatically generate train to platforming assignments for all 530 Belgian stations in only 10 minutes of optimisation time for all 530 models together. Both our macroscopic timetabling tool and platforming and routing tool are integrated and useable at Infrabel. status: published

The optimization problem, considered in this research, is about determining the best possible improvement of an incomplete network such that the total travel time of the vehicles on the network is minimized. Three possible improvements are studied in this research: adding an extra road to the network, widening one of the existing roads and converting an existing road into a one-way road with a higher speed. Due to the complexity of the problem, a metaheuristic is introduced to find nearoptimal solutions for cases of realistic size. is metaheuristic combines a construction part and an analysis part. During the construction part, routes for the vehicles are constructed in the current network using a fast Variable Neighborhood Search. In the second part of the metaheuristic, the constructed routes are analyzed heuristically in order to determine a good improvement of the network. Benchmark instances are created based on a realistic road network with varying numbers of customers and vehicles. The results show that a reduction in total travel time of the vehicles of up to more than 3% can be obtained by improving the network. Moreover, the total travel time in the network which is improved by our metaheuristic is on average only 0.09% longer than in the optimally improved network. ispartof: pages:13-16 ispartof: Proceedings of the EU/ME workshop on Design and Analysis of Metaheuristics pages:13-16 ispartof: EU/ME workshop on Design and Analysis of Metaheuristics location:Antwerp date:17 Mar - 18 Mar 2016 status: published

A personalised electronic tourist guide assists tourists in planning and enjoying their trip. The planning problem that needs to be solved, in real-time, can be modelled as a Team Orienteering Problem with Time Windows (TOPTW). In the TOPTW, a set of locations is given, each with a score, a service time and a time window. The goal is to maximise the sum of the collected scores, by a fixed number of routes. The routes allow to visit locations at the right time and they are limited in length. The main contribution of this paper is a simple, fast and effective iterated local search meta-heuristic to solve the TOPTW. An insert step is combined with a shake step to escape from local optima. The specific shake step implementation and the fast evaluation of possible improvements, produces a heuristic that performs very well on a large and diverse set of instances. The average gap between the obtained results and the best-known solutions is only 1.8% and the average computation time is decreased with a factor of several hundreds. For 31 instances, new best solutions are computed. ispartof: Computers & operations research vol:36 issue:12 pages:3281-3290 status: published

This article provides a comprehensive literature review and classification method for data mining techniques applied to academic libraries. To achieve this, forty-one practical contributions over the period 1998-2014 were identified and reviewed for their direct relevance. Each article was categorized according to the main data mining functions: clustering, association, classification, and regression; and their application in the four main library aspects: services, quality, collection, and usage behavior. Findings indicate that both collection and usage behavior analyses have received most of the research attention, especially related to collection development and usability of websites and online services respectively. Furthermore, classification and regression models are the two most commonly used data mining functions applied in library settings. Additionally, results indicate that the top 6 journals of articles published on the application of data mining techniques in academic libraries are: College and Research Libraries, Journal of Academic Librarianship, Information Processing and Management, Library Hi Tech, International Journal of Knowledge, Culture and Change Management, and The Electronic Library. Scopus is the multidisciplinary database that provides the best coverage of journal articles identified. To our knowledge, this study represents the first systematic, identifiable and comprehensive academic literature review of data mining techniques applied to academic libraries. ispartof: Journal of Academic Librarianship vol:41 issue:4 pages:499-510 status: published

E-content revolution, technological advances, and ever-shrinking budgets oblige libraries to efficiently allocate their limited resources among collection and services. Unfortunately, this resource allocation is a complex process due to the diversity of data sources and formats required to analyze prior to decision-making, as well as the lack of efficient methods of integration. The contribution of this article is twofold. We first propose an evaluation framework to holistically assess academic libraries. To do so, a four-pronged theoretical framework is used in which the library system and collection are analyzed from the perspective of users and internal stakeholders. The second contribution of this article is to present a data warehouse architecture that integrates, processes, and stores the holistic-based collected data. By proposing this holistic approach, authors aim to provide an integrated solution that assists library managers to make economic decisions based on an "as realistic as possible" perspective of the library situation. ispartof: Library Quarterly vol:85 issue:3 pages:295-318 status: published

ispartof: Tijdschrift Vervoerswetenschap vol:51 issue:1 pages:49-66 status: published

With our Periodic Event Scheduling Problem (PESP) based timetabling method we are able to produce a passenger robust timetable for all 88 hourly passenger trains running on tracks managed by the Danish Infrastructure Manager Banedanmark. The objective function of our model is the total expected passenger journey time in practice and is minimised. The result of this is that the produced timetable reduces the expected journey time of all corresponding train passengers together by 2.9% compared to the original timetable dened by Banedanmark. Our simulations show that the average probability of missing a transfer is also reduced from 11.34% to 2.45%. The computation of this timetable takes only 65 minutes. The major innovations of our approach are the addition of a complete objective function to the PESP model and the addition of a particular cycle constraint set that reduces computation times. In this paper, we demonstrate that these combined innovations result in a method that quickly generates cyclic timetables for a train network spanning an entire country and that these timetables also reduce the expected passenger travel time in practice. no isbn ispartof: Proceedings of the Conference on Advanced Systems in Public Transport ispartof: Conference on Advanced Systems in Public Transport location:Rotterdam date:19 Jul - 23 Jul 2015 status: published

The increasing importance of public transport incurs a growing need for accurate trains. Though timetabling can account for possible delays, in practice, external events regularly lead to delays. Once trains are deviating from their schedule, conflicts can occur. A conflict implies that (at least) two trains require the same part of the infrastructure at the same time. Conflicts need to be resolved quickly in a way that disturbs the system as little as possible. Therefore, the impact on the whole network should be taken into account when solving conflicts. This paper discusses and evaluates three heuristics that solve conflicts, based on a detailed simulation. The first two are based on common dispatching rules, the last one is a self-designed strategy that incorporates the secondary conflicts in a way that it tries to limit the duration of all conflicts in the next hour. Given delay scenarios, the three dierent strategies are compared based on secondary delays and computation time. ispartof: Conference on Advanced Systems in Public Transport location:Rotterdam date:19 Jul - 23 Jul 2015 status: published

When developing a public transportation service, the network design is one of the crucial stages. In this paper, a sensitivity analysis of the network design stage is discussed in order to analyse the changes to the network when certain input parameters are changed. The proposed methodology consists of three main phases: the selection of the input parameters that will be changed in the sensitivity analysis and the definition of scenarios in which these parameters will be changed; the search for the best network design for each scenario using a Genetic Algorithm; and the analysis of the results. The Demand, Travel Times, Line Length, Fleet Size, Stop Time and Transfer Time are the selected input parameters used to create a total of 33 scenarios. The infrastructure used in this study is a benchmark network of 15 nodes. The resulting bus networks were analysed and compared. ispartof: Conference on Advanced Systems in Public Transport location:Rotterdam date:19 Jul - 23 Jul 2015 status: published

Infrabel, the manager of the Belgian Railway Infrastructure, is responsible for developing the railway timetables over the Belgian railway network. By the year 2013, Infrabel wants to introduce a new timetable which is delay resistant. To achieve this task, Infrabel made an appeal to the Centre for Industrial Management (CIB) of the KU Leuven.The objective of this research can be formulated as follows: Develop principles that make the railway timetable more robust. In general, a railway timetable is said to be robust if it is delay resistant. This is a rather vague description, but rarely a formal definition of robustness is given. That is why the first part of this research will be about an exact definition of a robust railway timetable.As one delayed train can have a large influence on the punctuality of other trains, the goal of this research can also be stated as to minimize the delay propagation throughout the entire network. status: published

TDABC is a relatively new costing management technique, initially developed for manufacturing processes, which is gaining attention in libraries. This is because TDABC is a fast and simple method that only requires two parameters, an estimation of time required to perform an activity and the unit cost per time of supplying capacity. A few case studies have been documented with regard to TDABC in libraries; all of them being oriented to analyse specific library activities such as inter-library loan, acquisition and circulation processes. The primary focus of this paper is to describe TDABC implementation in one of the most important library processes, namely cataloguing. In particular, original and copy cataloguing are analysed through a case study to demonstrate the applicability and usefulness of TDABC to perform cost analysis of cataloguing processes. ispartof: The Liber Quarterly vol:23 issue:3 pages:160-186 status: published

If railway companies ask for station capacity numbers, their underlying question is in fact one about the platformability of extra trains. Train platformability depends not only on the infrastructure, buffer times, and the desired departure and arrival times of the trains, but also on route durations, which depend on train speeds and lengths, as well as on conflicts between routes at any given time. We consider all these factors in this paper. We assume a current train set and a future one, where the second is based on the expected traffic increase through the station considered. The platforming problem is about assigning a platform to each train, together with suitable in- and out-routes. Route choices lead to different route durations and imply different in-route-begin and out-route-end times. Our module platforms the maximum possible weighted sum of trains in the current and future train set. The resulting number of trains can be seen as the realistic capacity consumption of the schedule. Our goal function allows for current trains to be preferably allocated to their current platforms. Our module is able to deal with real stations and train sets in a few seconds and has been fully integrated by Infrabel, the Belgian Infrastructure Management Company, in their application called Ocapi, which is now used to platform existing and projected train sets and to determine the capacity consumption. publisher: Elsevier articletitle: The train platforming problem: The infrastructure management company perspective journaltitle: Transportation Research Part B: Methodological articlelink: http://dx.doi.org/10.1016/j.trb.2014.01.004 content_type: article copyright: Copyright © 2014 Elsevier Ltd. All rights reserved. ispartof: Transportation Research Part B vol:61 pages:55-72 status: published

The decision-making process in academic libraries is paramount; however highly complicated due to the large number of data sources, processes and high volumes of data to be analyzed. Academic libraries are accustomed to producing and gathering a vast amount of statistics about their collection and services. Typical data sources include integrated library systems, library portals and online catalogues, systems of consortiums, quality surveys and university management. Unfortunately, these heterogeneous data sources are only partially used for decision-making processes due to the wide variety of formats, standards and technologies, as well as the lack of efficient methods of integration. This article presents the analysis and design of an integrated decision support system for an academic library. Firstly, a holistic approach documented in a previous study is used for data collection. This holistic approach incorporates key elements including process analysis, quality estimation, information relevance and user interaction that may influence a library’s decision. Based on the mentioned approach above, this study defines a set of queries of interest to be issued against the integrated system proposed. Then, relevant data sources, formats and connectivity requirements for a particular example are identified. Next, data warehouse architecture is proposed to integrate, process, and store the collected data transparently. Eventually, the stored data are analyzed through reporting techniques such as on-line analytical processing tools. By doing so, the article provides the design of an integrated solution that assists library managers to make tactical decisions about the optimal use and leverage of their resources and services. no isbn ispartof: pages:1-12 ispartof: Proceedings of IATUL Conferences pages:1-12 ispartof: 35th Annual IATUL Conference location:Helsinki, Finland date:2 Jun - 5 Jun 2014 status: published

The cycle trip planning problem (CTPP) can be formulated as a variant of the arc orienteering problem (AOP). The CTPP aims at finding a route with the highest possible score, in a directed graph, among those having a total length that does not exceed some given upper bound. The contributions of this paper are a new mathematical programming model for the CTPP and two solution methods. The first is a branch-and-cut approach that is able to solve small problem instances to optimality and the second is a metaheuristic that solves CTPP and AOP instances of realistic size to near optimality. publisher: Elsevier articletitle: An extension of the arc orienteering problem and its application to cycle trip planning journaltitle: Transportation Research Part E: Logistics and Transportation Review articlelink: http://dx.doi.org/10.1016/j.tre.2014.05.006 content_type: article copyright: Copyright © 2014 Elsevier Ltd. All rights reserved. ispartof: Transportation Research E, Logistics and Transportation Review vol:68 pages:64-78 status: published

In order to improve the robustness of a railway system in station areas, this paper introduces an iterative approach to successively optimize the train routing through station areas and to enhance this solution by applying some changes to the timetable in a tabu search environment. We present our vision on robustness and describe how this vision can be used in practice. By introducing the spread of the trains in the objective function for the route choice and timetabling module, we improve the robustness of a railway system. Using a discrete event simulation model, the performance of our algorithms is evaluated based on a case study for the Brussels' area. The computational results indicate an average improvement in robustness of 6.2% together with a decrease in delay propagation of about 25%. Furthermore, the effect of some measures like changing the train offer to further increase the robustness is evaluated and compared. publisher: Elsevier articletitle: Improving the robustness in railway station areas journaltitle: European Journal of Operational Research articlelink: http://dx.doi.org/10.1016/j.ejor.2013.10.062 content_type: article copyright: Copyright © 2013 Elsevier B.V. All rights reserved. ispartof: European Journal of Operational Research vol:235 issue:1 pages:276-286 status: published

ispartof: pages:377-387 ispartof: Proceedings of the 3rd International Conference on Models and Technologies for Intelligent Transportation Systems 2013 vol:3 pages:377-387 ispartof: International Conference on Models and Technologies for Intelligent Transportation Systems (MT-ITS) location:Dresden, Germany date:2 Dec - 4 Dec 2013 status: published

In this paper, we consider complex, busy stations whose limited capacity is one of the main reasons of delay propagation. Our goal is to improve, during the planning phase, the robustness of a complex station by fully exploiting the potential of the available capacity. The main feature of our approach is the interaction between routing decisions, timetabling and platform assignments. By altering one of these, slack can be created to allow improvements by the others as well. An objective function that maximizes the time span between any two trains is defined and the timing of the trains and the way how trains are routed to the platforms are optimized in the scope of this objective. By maximizing the spread of the trains, potential conflicts are avoided which is beneficial for - but not identical to - robustness. Using our approach, the robustness in the station zone of Brussels, Belgium's main railway bottleneck, can be improved by 8%. Next to that, the amount of knock-on delay arising due to conflicts within this area can be halved. This performance of our approach is confirmed by a second case study based on the station zone of Antwerp. Young Railway Operations Research Award 2013 of IAROR. ispartof: pages:1-20 ispartof: 5th International Seminar on Railway Operations Modelling and Analysis - RailCopenhagen pages:1-20 ispartof: 5th International Seminar on Railway Operations Modelling and Analysis - RailCopenhagen location:Copenhagen, Denmark date:13 May - 15 May 2013 status: published

When evaluating and optimizing the national railway timetable for all passenger trains in Belgium, we use the criterium of expected total passenger travel time in practice. During evaluation, we measure this, during optimization, we try to minimize this. The focus in this paper is to analytically derive the total passenger time as a stochastic function of the schedule. In a previous paper [9], we already derived the necessary local passenger flows from ticket sales data. These flows will serve as fixed weights in this new objective function. We start from measured delays in the current schedule and assume that they can be described well by a negative exponential distribution. In the case of constructing an optimized schedule, we assume delays will also occur in the new schedule according to the same distribution. We believe this is a conservative assumption, since the optimized schedule will be more robust against delays. We then decompose the global schedule of actions into local actions or pairs of subsequent actions, and derive probabilities and objective functions on the corresponding one or two local actions only. We sum these local functions to obtain a global objective function. This then becomes the schedules’ global quality criterium. We linearize this and use the result as the objective function of a linear programming based optimizer. With this objective function, we optimized the train schedule for the Belgian railways, which proves the method is scalable to large and complex real-life problems. ispartof: pages:1-20 ispartof: 5th International Seminar on Railway Operations Modelling and Analysis - RailCopenhagen pages:1-20 ispartof: 5th International Seminar on Railway Operations Modelling and Analysis - RailCopenhagen location:Copenhagen, Denmark date:13 May - 15 May 2013 status: published

This article provides a comprehensive literature review of Time-Driven Activity Based Costing (TDABC), a relatively new tool to improve the cost allocation to products and services. After a brief overview of traditional costing and activity based costing systems (ABC), a detailed description of the TDABC model is given and a comparison made between this methodology and its predecessor ABC. Thirty-six empirical contributions using TDABC over the period 2004-2012 were reviewed. The results and conclusions of these studies are grouped according to the main areas of application of the method such as logistics, manufacturing, services, health, hospitality and nonprofit services. Potential benefits, and challenges are identified. ispartof: Review of Business and Economic Literature vol:58 issue:1 pages:34-64 status: published

Academic libraries have recently been subjected to continuous budget reductions, mainly due to the increasing costs of information and the global economic crisis. As the primary purpose of an academic library is to provide well-balanced collections and a wide range of services to support education and research, an efficient use and allocation of limited resources is vital. However, allocating resources such as money, staff, time, and infrastructure between the library collection and services represents a challenge due to the multitude of data sources required to consult during a decision-making process. Academic libraries are accustomed to keeping voluminous statistics on their collection and services; however these data are not fully used for decision-making processes due to the lack of an efficient structure for grouping this information. The authors in a previous study state that prior to decision making, data must be collected based on a holistic approach that incorporates all of the key elements that may influence a decision. It is in this sense that to holistically assess libraries, an approach combining a theoretical framework with several measurement tools is proposed in that study. Therefore, the aim of this paper is to document early experiences and lessons learned in implementing the holistic approach in an academic library in Belgium. To do so, the academic library is evaluated in two dimensions. The first dimension analyzes the library system and its collection, whereas the second dimension analyzes the perspective of both the user and the internal stakeholders. During the initial implementation stages, the proposed approach proved to be valuable to ensure a complete view of the library collection and services. There are, however, important considerations to be borne in mind such as the time required to implement the complete approach, as well as the need of a system to integrate the collected information. no isbn ispartof: pages:1-9 ispartof: Proceedings of IATUL Conferences pages:1-9 ispartof: 34th Annual IATUL Conference location:Cape Town, South Africa date:14 Apr - 18 Apr 2013 status: published

The Ministry of Education and Culture (MoEC) in Cyprus is focusing on moving towards transferable competencies and computer based learning environments as well as innovative models necessary for the new millennium challenges. The decision makers recognize that significant changes need to occur in several areas, but most of all concerning the use of information technology. The main objective of the project is to contribute to the development and modernization of the Cypriot educational system, by introducing and enhancing the use of information technology in the process of teaching/learning in the pre-university education. The Ministry of Education and Culture aims at encouraging innovative teaching and learning techniques and stimulating creativity among teachers and students, while offering a general framework for development of collaborative projects, allowing the actors enrolled in the educational system to participate in the information society development and the creation of the knowledge economy. This paper describes the approach that was taken for the implementation of a national eLearning implementation project in Cyprus. The paper describes the logical and physical architectures of the eLearning platforms. The paper analyses the challenges and risks faced by the project and in general by similar national-level projects in education and the main methods for mitigating them. Finally, the paper underlines lessons learnt and the degree of reusability and replicability of the implemented architecture. ispartof: pages:223-228 ispartof: LEVERAGING TECHNOLOGY FOR LEARNING, VOL II issue:2 pages:223-228 ispartof: eLSE 2012 - Leveraging Technology for Learning - Proceedings of the 8th International Scientific Conference "eLearning and Software for Education" ELSE location:Bucharest - Romania date:26 Apr - 27 Apr 2012 status: published

A theoretically calculated station capacity very often appears to be based on an unrealistic train set. By considering the actual, current, as well as future train set scenarios with increasing trac, we determine the realistic station capacity of the railway stations in Belgium. Our module is able to deal with real-life station and train sets in a few minutes and is now fully integrated in the software of Infrabel, the Belgian Railway infrastructure Management Company. ispartof: pages:1-4 ispartof: 2nd International Conference on Models and Technologies for ITS pages:1-4 ispartof: International Conference on Models and Technologies for ITS location:Leuven date:22 Jun - 24 Jun 2011 status: published

In optimizing the national railway timetable for the Belgian infrastructure company Infrabel, we use the quality criterium of minimizing expected total passenger travel time. Optimizing the timing of all trains fairly over all passengers requires passenger flow information. Focus is usually on determining the train service offer side, being the train timing, without considering the demand side data, being the passenger flow information. In this paper, we focus on passenger flow derivation. We start from train ticket sales data and use Dijkstra’s modified shortest path algorithm on the Belgian passenger train graph to determine a route per passenger origin destination station pair. We sum route passenger flows over all these routes. We also show how, in optimization of a timetable, timing and flows should be treated as interdependent. This means that we can use a process of iteration over these two phases, which we then call reflowing and retiming. The infrastructure company did not have this passenger flow information available for the current schedule, but they need it to optimize many decisions. We determined these passenger flows for the current timetable. We also give some recommendations regarding the improvement of passenger flow related data recording procedures, which would significantly improve passenger service. ispartof: pages:1-20 ispartof: Proceedings of 4th International Seminar on Railway Operations Modelling and Analysis (IAROR): RailRome2011 pages:1-20 ispartof: 4th International Seminar on Railway Operations Modelling and Analysis (IAROR) RailRome2011 location:Rome date:16 Feb - 18 Feb 2011 status: published

In the last decade many studies have been devoted to railway timetables for passenger trains. In countries like the Netherlands and Switzerland some new concepts were developed to obtain a better performance. Belgium, an important transit nation and the first in continental Europe with a railway, cannot lack behind. In this spirit, a research project about robustness of a timetable is initiated in close cooperation with Infrabel, the manager of the Belgian railway infrastructure. In this paper we present the first results of this research; a generic definition of robustness of a railway timetable is presented. Although many research was devoted to robust railway planning, there is lack of a general definition of timetable robustness. We present a general definition and use this definition to measure how robust the current schedule is. This definition is the first step towards a new timetable that is significantly more robust from the passengers’ point of view. ispartof: pages:1-20 ispartof: Proceedings of 4th International Seminar on Railway Operations Modelling and Analysis (IAROR): RailRome2011 pages:1-20 ispartof: 4th International Seminar on Railway Operations Modelling and Analysis (IAROR) RailRome2011 location:Rome date:16 Feb - 18 Feb 2011 status: published

During the last decade, a number of challenging applications in logistics, tourism and other fields were modelled as orienteering problems (OP). In the orienteering problem, a set of vertices is given, each with a score. The goal is to determine a path, limited in length, that visits some vertices and maximises the sum of the collected scores. In this paper, the literature about the orienteering problem and its applications is reviewed. The OP is formally described and many relevant variants are presented. All published exact solution approaches and (meta)heuristics are discussed and compared. Interesting open research questions concerning the OP conclude this paper. ispartof: European Journal of Operational Research vol:209 issue:1 pages:1-10 status: published

When tourists visit a city or region, they cannot visit every point of interest available, as they are constrained in time and budget. Tourist recommender applications help tourists by presenting a personal selection. Providing adequate tour scheduling support for these kinds of applications is a daunting task for the application developer. The objective of this paper is to demonstrate how existing models from the field of Operations Research (OR) fit this scheduling problem, and enable a wide range of tourist trip planning functionalities. Using the Orienteering Problem (OP) and its extensions to model the tourist trip planning problem, allows to deal efficiently with a vast number of practical planning problems. ispartof: Journal of Information Technology & Tourism vol:12 issue:4 pages:305-315 status: published

status: published

Generating personalized tourist routes based on a tourist’s interests and constraints is an upcoming trend in tourist applications. This problem can be directly related to the Multi Constrained Team Orienteering Problem with Time Windows (MCTOPTW). The MCTOPTW consists of a set of locations, each of them with a certain score, a time window and one or more associated attributes, such as an entrance fee. Each attribute type has an associated constraint with a maximum allowed value for a route, such as a limited budget. Visiting a location within its time window allows collecting its score as a reward. The goal is to determine a fixed number of routes that maximize the collected score without violating any of the constraints. This paper describes an iterated local search metaheuristic to solve the MCTOPTW, in order to generate personalized tourist routes in real-time. Extensive experimental results with new and existing benchmark instances prove the appropriateness of the algorithm. status: published

When tourists are at a destination, they typically search for information in the Local Tourist Organizations. There, the staff categorizes tourists’ profile and restrictions. Combining this information with their up-to-date knowledge about the local attractions, weather and public transportation, they suggest a personalised route for the tourist agenda. This paper presents an intelligent routing system for a Personalised Electronic Tourist Guide to fulfil the same task. This system improves the automatic route creation functionality of existing PETs to solve better the needs of tourists in several aspects: i) it includes public transportation, ii) it takes varying travelling times into account, adapting to real circumstances as rush-hours, iii) it calculates routes in real time to react to unexpected events, iv) it applies last generation heuristics from Operations Research to create routes efficiently, even in destinations with a large number of point of interests and a dense public transportation network. ispartof: pages:185-197 ispartof: Information and Communication Technologies in Tourism 2009 pages:185-197 ispartof: ENTER location:Amsterdam status: published

This paper introduces a Greedy Randomised Adaptive Search Procedure (GRASP) for solving the Team Orienteering Problem (TOP). That is a particular routing problem in which a score is earned for visiting a location. The objective is to maximise the sum of the scores of a fixed number of routes, while not exceeding a given time budget for each route. The memoryless GRASP approach is extended by adding a long term adaptive memory component, namely a path relinking procedure. Both versions of the approach are tested using a large set of test instances from the literature. ispartof: pages:1-9 ispartof: EU/MEeting 2008 on metaheuristics for logistics and vehicle routing vol:2008 pages:1-9 ispartof: EU/MEeting 2008 on metaheuristics for logistics and vehicle routing location:Troyes, France status: published

This article aims to analyse the role of library managers as change agent when implementing Library 2.0, using transformational leadership and stakeholder management approaches. To do so, a case study in a Latin American academic library was performed. The experiences acquired for a period of six years were analysed, during which three library managers were involved in managing change. Qualitative data from documents, interviews, and observations were collected, and qualitative analysis methods were used to obtain in-depth understanding of the change process. Results show that lack of transformational leadership and stakeholder management contribute to delayed implementation and limited adoption of innovations. Although library managers recognized the importance of different stakeholders to implement changes, they did not apply systematic and proactive strategies to define and manage them. All in all, library managers should be trained as change agents, with emphasis on transformational leadership and stakeholder management skills. ispartof: The Liber Quarterly vol:24 issue:2 pages:55-83 status: published