Joaquin Rodriguez | Institut français des scineces et technologies des transports, de l'aménagement et des réseaux (original) (raw)

Papers by Joaquin Rodriguez

Transportation Research Part B: Methodological, 2016

This work was partially supported by the "Ambassade de France en Italie" with a threemonth MAE mo... more This work was partially supported by the "Ambassade de France en Italie" with a threemonth MAE mobility scholarship for PhD candidates. We would like to thank the anonymous reviewers for their helpful and constructive remarks.

Based on passenger mobility knowledge, this research presents a model for the design of passenger... more Based on passenger mobility knowledge, this research presents a model for the design of passenger-oriented lines for SNCF Transilien (major railway operator for the Parisian suburban mass transit). In the Paris area, the traffic has increased by 30% over the last decade, reaching 3.2 million passengers a day on the network. We have developed a new method that proposes a line planning process aiming at the best quality level for passengers, and at reasonable costs. First, we introduce indicators to characterize the performance of railway services, with the traveler's and the operator's points of view. Then, a method to solve a graph theory-based multiobjective model for the Line Planning Problem is presented, minimizing both users' discomfort and operating costs. This method provides all efficient solutions. Experimental results on SNCF Transilien real instances are presented. Several objectiv...

Scheduling theory (ST) is a formal framework which have been used many times over the last decade... more Scheduling theory (ST) is a formal framework which have been used many times over the last decade as starting point to model railway traffic management. Graph theory (GT), mathematical programming (MP) or constraint programming (CP) have also be used as additional steps to scheduling theory. This is illustrated in figure 1. The last step is a solution algorithm that is many times based a complete or partial enumeration procedure (EP) of feasible solutions where large subsets are discarded. This article will focus on the path ST → CP → EP to solve railway management problems. I will first briefly introduce each field, and after applications to the railway traffic management.

EURO Journal on Transportation and Logistics, 2021

This is a PDF file of an article that has undergone enhancements after acceptance, such as the ad... more This is a PDF file of an article that has undergone enhancements after acceptance, such as the addition of a cover page and metadata, and formatting for readability, but it is not yet the definitive version of record. This version will undergo additional copyediting, typesetting and review before it is published in its final form, but we are providing this version to give early visibility of the article. Please note that, during the production process, errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.

Real time railway traffic management modeling track-circuits

2018 21st International Conference on Intelligent Transportation Systems (ITSC)

The real-time railway traffic management problem (rtRTMP) aims to solve time-overlapping conflict... more The real-time railway traffic management problem (rtRTMP) aims to solve time-overlapping conflicting track requests due to traffic disturbances. The size of the problem and the time required to solve it are affected by the number of routing alternatives available to each train. The real-time train routing selection problem (rtTRSP) chooses a feasible routing subset for each train to use as input for the rtRTMP. Recently, a computational analysis has been performed via Ant Colony Optimization and the RECIFE-MILP solver. This paper generalizes such analysis by considering a different rtRTMP model, objective function and solution approach. We adopt the AGLIBRARY solver, which is based an alternative graph model of the problem and minimizes the maximum consecutive delay. The aim is to develop real-time disturbance response strategies and to quantify the advantages of the selection of a subset of routings when using different solvers. We analyze how changes in the rtRTMP model are reflected in the rtTRSP and which modifications are required. The computational analysis is performed on two French infrastructures: the line around the city of Rouen and the Lille terminal station area. The analysis shows that solving the rtTRSP helps both solvers significantly, even if they are based on different models, objectives and algorithms.

Pour faire face a l'accroissement de la demande du trafic sans faire de nouveaux investisseme... more Pour faire face a l'accroissement de la demande du trafic sans faire de nouveaux investissements, les gestionnaires d'infrastructure se penchent sur les possibilites d'ameliorer l'exploitation de certains points critiques du reseau. Ces points critiques sont parcourus par des circulations mixtes (fret, grande ligne, TGV, . . .) avec de nombreux types de conflits. Les operateurs qui gerent les circulations doivent prendre des decisions difficiles afin d'arbitrer ces conflits. La difficulte provient principalement des nombreuses contraintes qu'il faut considerer. Le travail presente dans ce chapitre porte sur la resolution du probleme d'optimisation de la gestion operationnelle des circulations. Le modele qui est propose pour traiter ce probleme s'appuie sur la theorie de l'ordonnancement et la programmation par contraintes. La presentation du modele se focalise sur la justification des hypotheses de modelisation. Ces hypotheses sont comparees avec ...

Automatic real-time control of railway traffic perturbations has recently received the attention ... more Automatic real-time control of railway traffic perturbations has recently received the attention of practitioners. The aim is to make use of mathematical algorithms to maintain the required service availability during unplanned disturbances to operations. In the literature many tools for real-time traffic control are proposed, but their effects on traffic have never been studied neither in real life nor in realistic simulation environments. We can mention only a few pilot tests and a unique installation in the Lotschberg Base tunnel in Switzerland, which is in any case an ad-hoc implementation not extendible to other case studies. In this paper we present the ON-TIME framework for the real-time management of railway traffic perturbations. The main innovation is a standard web service-oriented architecture that ensures scalability and flexibility. A standard RailML interface is used for the input/output data of the modules, allowing immediate applicability of the framework to any net...

In this paper we propose a reformulation of RECIFE-MILP aimed at boosting the algorithm performan... more In this paper we propose a reformulation of RECIFE-MILP aimed at boosting the algorithm performance. RECIFE-MILP is a mixed integer linear programming based heuristic for the real-time railway traffic management problem, that is the problem of re-routing and rescheduling trains in case of perturbation in order to minimize the delay propagation. The reformulation which we propose exploits the topology of the railway infrastructure. Specifically, it capitalizes on the implicit relations between routing and scheduling decisions to reduce the number of binary variables of the formulation. In an experimental analysis based on realistic instances representing traffic in the French Pierrefitte-Gonesse junction, we show the performance improvement achievable through the reformulation.

Maintenance Activities (MA's) are necessary to sustain the state and functionality of the rai... more Maintenance Activities (MA's) are necessary to sustain the state and functionality of the railway infrastructure. However, MA's directly or indirectly affect the circulations of trains in the network, either by banning or by restraining them in some locations. Therefore, an efficient coordination between MA's and train irculations is necessary to optimize the railway capacity utilization. In the first part of this work, we present a MILP formulation for rescheduling and rerouting trains that are directly or indirectly affected by MA's. This formulation can be used to validate or to optimize the train schedules and routes with great precision, since a microscopic perspective of the infrastructure and rolling stock is considered. In the second part, we discuss some experimental results obtained with our formulation in a real-world case study in the French railway network. Finally, we present our conclusions and perspectives.

In this paper an approach is proposed for optimization of speed profiles in railway integrating e... more In this paper an approach is proposed for optimization of speed profiles in railway integrating energy saving. This approach deals with a multi-objective problem involving three criteria: reduction of the travel duration, reduction of the delays and minimization of the energy consumption. Based on a state of the art evolutionary algorithm, the proposed approach searches for diversified solutions in a continuous search space. These solutions are evaluated and compared according to the Pareto approach in such a way that the proposed solutions are different and incomparable, in order to help the decision makers. After having reminded railway dynamics elements, the approach is detailed as well as the evolutionary algorithm and its problem-related components. Two case studies (the Gonesse junction and the line Saint- ´ Etienne – Rive de Giers in France) and results are then provided and analyzed.

In railway traffic management problems, a frequent approximation is the one of fixed-speed, i.e. ... more In railway traffic management problems, a frequent approximation is the one of fixed-speed, i.e. the trains either run at their cruise speed or are stopped immediately without considering the acceleration and deceleration phases due to arising conflicts on the infrastructure. We assess the validity of the fixed-speed approximation for train speed dynamics in the real time Railway Traffic Management Problem. This is done through a statistical analysis on a number of perturbed scenarios on different railway infrastructures, for different objective functions commonly used in the literature. For each scenario, we analyze the ranking of the generated solutions both in the fixed-speed approximation, obtained by solving the optimization model, and with the variable-speed dynamics, obtained through micro simulation with the OpenTrack software. Our results indicate that some objective functions can be considered reliable when used in conjunction with the fixed-speed approximation, while othe...

This paper presents a comparative study of an automatic dedicated single track people mover and a... more This paper presents a comparative study of an automatic dedicated single track people mover and an automatic dedicated double track people mover. The study examined both `system' and infrastructure aspects. The paper describes the specific operational features of this type of line. An application to a medium-sized French city demonstrates the feasibility of this mode of operation and the savings which can result.

In railway timetabling, the train running times are often known as the shortest durations between... more In railway timetabling, the train running times are often known as the shortest durations between two stations increased of some percent of time. The running times are estimated by constructing the speed profiles that the trains must hold along the track. In this paper, an approach is proposed to compute several speed profiles for a same travel. The optimization approach involves two objectives optimized concurrently: the minimization of the journey duration and the minimization of the energy spent for the travel. Based on an evolutionary bi-objective algorithm, the optimization approach is applied to three instances and results are reported and analyzed.

In railway operations, a timetable is established to determine the departure and arrival times fo... more In railway operations, a timetable is established to determine the departure and arrival times for the trains or other rolling stock at the different stations or relevant points inside the rail network or a subset of this network. The elaboration of this timetable is done to respond to the commercial requirements for both passenger and freight traffic, but also it must respect a set of security and capacity constraints associated with the railway network, rolling stock and legislation. Combining these requirements and constraints, as well as the important number of trains and schedules to plan, makes the preparation of a feasible timetable a complex and time-consuming process, that normally takes several months to be completed. This article addresses the problem of generating periodic timetables, which means that the involved trains operate in a recurrent pattern. For instance, the trains belonging to the same train line, depart from some station every 15 minutes or one hour. To tackle the problem, we present a constraint-based model suitable for this kind of problem. Then, we propose a genetic algorithm, allowing a rapid generation of feasible periodic timetables. Finally, two case studies are presented, the first, describing a sub-set of the Netherlands rail network, and the second a large portion of the Nord-pas-de-Calais regional rail network, both of them are then solved using our algorithm and the results are presented and discussed.

Public Transport, 2015

Transilien, the branch of SNCF in charge of operating the main urban railroad network in the area... more Transilien, the branch of SNCF in charge of operating the main urban railroad network in the area of Paris, faces a regular increase of passengers flows. The planning of railway operations is made carefully: simulation runs permit to assess the timetable stability. However, many disturbance appears and cause trains delays. Due to the nature of the railroad network those delays are cumulative and an on-line update of the timetable is not always successful in maintaining the trains schedule. In this tensed context, operators are searching solutions to better use the infrastructure capacity and better service quality. A needed step towards this objective is a better understanding of the phenomena of disruptions. In particular because the expansion of congestion is not clearly understood until now. This paper explores the possibility to transpose a traffic flow theory tool, the network fundamental diagram, in the field of dense railroad traffic. Railroad traffic is different of road traffic by many ways: railways are a planned system, traffic volume does not satisfy the continuum hypothesis, stations force stops and the signalization system brings a discrete behavior. Despite those big differences we show how to build a network fundamental diagram for a railroad system and how to interpret some obtained shapes for those diagrams. These diagrams gives us some means to compare planned and reality. We also identify the limits that need to be overcome to take benefits of the road traffic tools in railroad traffic analysis.

Transportation Research Part B: Methodological, 2016

EURO Journal on Transportation and Logistics, 2021

Real time railway traffic management modeling track-circuits

2018 21st International Conference on Intelligent Transportation Systems (ITSC)

Public Transport, 2015