Greek Railways Research Articles

Development of a Methodological Approach for the Design of Train Speed Trajectory Diagrams for the Suburban Railways—Application on the Greek Railway Line Athens–Chalkida

Development of a Methodological Approach for the Design of Train Speed Trajectory Diagrams for the Suburban Railways—Application on the Greek Railway Line Athens–Chalkida

Train vs. airplane: Investigating the potential modal share shift and the environmental impact for a reduced train travel time from Thessaloniki to Athens

This paper investigates the impact of routing a train between Athens and Thessaloniki, completing the journey in 2.5 hours, on modal share. With high expectations for the modernization of the Greek railway system, particularly the Athens-Thessaloniki route, and recent tragic events involving the railway, this study aims to shed light on the potential effects of such an improvement. A questionnaire survey was conducted at Thessaloniki Airport “Makedonia” to gather data on travel time, ticket prices, and other factors influencing travelers’ mode choices for the Athens-Thessaloniki route. The survey included 181 participants, most of whom had an income equal to or below the average monthly income. Results revealed that if the new rail system was implemented at equal cost, 63% of respondents would choose the train over the airplane, citing long transit times, waiting time, extra costs, and luggage restrictions as primary factors favoring the train. However, 8% expressed concerns about the reliability and adherence to estimated travel times. Overall, the research concludes that, despite the recent tragedy, the modernized train system could significantly increase its modal share and offer positive environmental benefits by reducing the journey time to 2.5 hours.

Seismic fragility analysis of railway reinforced concrete bridges considering real‐time vehicle‐bridge interaction with the aid of co‐simulation techniques

AbstractBased on past earthquake events, bridges are the most critical and most vulnerable component of road and rail transport systems, while bridge damage is related to substantial direct and indirect losses. For the case of railway bridges, the estimation of seismic fragility is a rather complex and computationally demanding procedure given the real‐time interaction of the train movement and the bridge and the different failure modes of subsystems. Considering vehicle‐bridge interaction (VBI) in the frame of railway bridge fragility analysis is rather challenging, requiring analysis of the bridge and the vehicle at every time step. Partitioning of the coupled VBI problem proposing a weak formulation scheme and a set of second‐order ordinary differential equations (ODEs) is performed in a way that allows for independent subsystem (vehicle and bridge) analysis. Several methodologies are available in the literature to estimate the seismic fragility of train‐bridge systems that ignore the nonlinear behavior of the bridge during earthquake loading, the step‐by‐step VBI, and the different failure modes of critical components. The scope of this research paper is to propose a real‐time component‐based methodology for estimating bridge fragility curves, considering all critical components and failure modes of subsystems. The two subsystems are incorporated in a uniform software platform using the co‐simulation approach and a Gauss‐Seidel communication pattern. The vehicle‐rail system is solved using a C++ tailor‐made code, including a mathematical formulation that is based on the description of the constrained problem with a set of pure ODEs, avoiding issues related to differential‐algebraic equations, constraint violation, drifts, energy loss, stability, and convergence. The vehicle subsystem is solved using multibody dynamics (MBD), while the bridge subsystem is modeled and solved using OpenSees.py. An ad‐hoc software for the implementation of the probabilistic framework and the derivation of fragility curves is developed in Python. A novel methodological procedure is proposed, dully tailored to the demanding estimation of fragility curves of the coupled vehicle‐bridge problem. The step‐by‐step solution of subsystems is performed using the co‐simulation technique. Real‐time interaction is allowed, considering a rational transfer of force, velocity, and displacement between subsystems. The methodology along with the software developed is described and applied to two representative reinforced concrete (RC) bridges of the Greek railway network (v≤200 m/sec), providing fragility curves (i.e., the seismic performance for various levels of earthquake intensity) for the coupled system. The results are discussed and assessed.

Predictive Maintenance Using Machine Learning and Data Mining: A Pioneer Method Implemented to Greek Railways

In every business, the production of knowledge, coming from the process of effective information, is recognized as a strategic asset and source of competitive advantage. In the field of railways, a vast amount of data are produced, which is necessary to be assessed, deployed in an optimum way, and used as a mechanism, which will lead to making the right decisions, aiming at saving resources and maintain the fundamental principle of the railways which is the passengers’ safety. This paper uses stored-inactive data from a Greek railway company, and uses the method of data mining and applies machine learning techniques to create strategic decision support and draw up a risk and control plan for trains. We make an effort to apply Machine Learning open source software (Weka) to the obsolete procedures of maintenance of the rolling stock of the company (hand-written work orders from the supervisors to the technicians, dealing with the dysfunctions of a train unit by experience, the lack of planning and coding of the malfunctions and the maintenance schedule). Using the J48 and M5P algorithms from the Weka software, data are recorded, processed, and analyzed that can help monitor or discover, with great accuracy, the prevention of possible damage or stresses, without the addition of new recording devices—monitoring on trains, with the aim of predicting the diagnosis of the train fleet. The innovative method is capable of being used as a tool for the optimization of the management’s performance of the trains to provide the appropriate information for the implementation of planning and the technical ability of the trains in order to achieve the greatest target of importance for the railways, which is the passengers’ safety.

Business Intelligence and Machine Learning Methods for Predictive Maintenance in Greek railways

The extraction of useful information supports the process of making business decisions. In every mechanical process, application or service, the periodic maintenance of the necessary equipment is an expensive process and therefore the technicians and the supervisors have the responsibility of the proper decision making. At the railway companies, a huge amount of data is produced which, with the appropriate processing and smart business systems, can attribute quality information and knowledge. In this paper, the benefits of the business intelligence are presented with the techniques of machine learning and data mining involved of the Greek railway companies, which use obsolete procedures of maintenance. In addition, a study of the present situation is held as well as a record of the needs and requirements of the railway companies. At the same time, tools (open source of low cost) of machine learning and data mining are examined that can assist on the creation of a new strategic support of decisions for the development of the predictive maintenance of the Greek railways making a new complete system of business intelligence. Finally, the results and the motives of the railway companies are presented in order to create applications which can constitute the basic tool for the improvement of making decisions by the business’s administration.

Optimization of the Procedures for Checking the Functionality of the Greek Railways: Data Mining and Machine Learning Approach to Predict Passenger Train Immobilization

Optimization of the Procedures for Checking the Functionality of the Greek Railways: Data Mining and Machine Learning Approach to Predict Passenger Train Immobilization

Machine Learning: Prospects, Opportunities and Benefits to the Greek Railways

Machine Learning: Prospects, Opportunities and Benefits to the Greek Railways

A tale of two railways and the Reuter family

Between the nineteenth and twentieth centuries, the influence of Baron Julius de Reuter and his famous agency, Reuters, was evident in his and his family's investments around the world. By looking at the histories of the Reuter Concession and the Greek Railway Concession, this work aims to offer insight into the international politics of certain governments and the value of news as a commodity at the time. The Reuter Concession illustrates part of the British-Russian conflict over Persia while the Greek Railway Concession demonstrates British policy toward the Ottoman Empire and Greco-Ottoman relations.

Development and use of a model for the investigation of energy and emission aspects on the Athens-Thessaloniki rail intermodal freight transport

Environmental protection is an issue that rises in importance in the agenda of the priorities in transportation sector. Railways are perceived to contribute positively towards such a direction. The current work focuses on the actual parameters that affect energy and emissions in rail freight transport. These parameters were investigated using a model. Input variables include technical and operational characteristics of the railway track, the rolling stock and the loading units as well as the restrictions of the wagons' loading process, which prevent railways to operate at full capacity. The model was validated on the main Greek railway corridor connecting Athens to Thessaloniki. The analysis revealed and quantified the impacts affecting energy and emissions: train load factor, train speed, gradient profile of railway track, rolling stock types, payload of transported loading units, rules of efficient wagon loading, fuel type and emission factor for electricity generation in the specific country. Comparisons with pure road transport and sensitivity analysis were also carried out on the Athens-Thessaloniki case study.

Development and use of a model for the investigation of energy and emission aspects on the Athens-Thessaloniki rail intermodal freight transport

Environmental protection is an issue that rises in importance in the agenda of the priorities in transportation sector. Railways are perceived to contribute positively towards such a direction. The current work focuses on the actual parameters that affect energy and emissions in rail freight transport. These parameters were investigated using a model. Input variables include technical and operational characteristics of the railway track, the rolling stock and the loading units as well as the restrictions of the wagons' loading process, which prevent railways to operate at full capacity. The model was validated on the main Greek railway corridor connecting Athens to Thessaloniki. The analysis revealed and quantified the impacts affecting energy and emissions: train load factor, train speed, gradient profile of railway track, rolling stock types, payload of transported loading units, rules of efficient wagon loading, fuel type and emission factor for electricity generation in the specific country. Comparisons with pure road transport and sensitivity analysis were also carried out on the Athens-Thessaloniki case study.

The Euro Crisis: Mission Accomplished?

The Euro Crisis: Mission Accomplished?

Rail infrastructure charging in Hellenic railways

In this paper we consider marginal cost estimation in Greek railways over the period 2000–2004. Marginal cost estimation has been recently an active area of research when disaggregated data by line of operation are available but factor price data are not available. We propose panel data techniques to deal with the problem of statistical efficiency of parameters estimators. Our estimates show that marginal cost in Greek railways is comparable to the estimates in other European countries.

Sleep-Disordered Breathing and Quality of Life of Railway Drivers in Greece*

Sleep-disordered breathing (SDB) and especially obstructive sleep apnea (OSA) are associated with daytime sleepiness and an increased risk for motor vehicle crashes. Previous studies have assessed the prevalence of OSA among professional drivers, but no study so far has focused on railway drivers. The aim of this study was to assess the prevalence of SDB among Greek railway drivers, and correlate it with daytime sleepiness, quality of life, and symptoms. The following three different questionnaires were anonymously answered by 226 train drivers: a general questionnaire on their demographics and sleep habits; the Greek version of the Epworth sleepiness scale (ESS); and the Medical Outcomes Study 36-item short form (SF-36). Of the 226 drivers, 50 underwent a sleep study, a physical examination, and an assessment of their respiratory function. Participants were all men, had a mean (+/-SD) age of 46.9+/-3.9 years, were overweight (mean body mass index [BMI], 28.7+/-3.7 kg/m2), and were smokers (59.7%). Snoring was reported by 69.9% of them, and apneas by 11.5%. The mean ESS score was 5.4+/-3.2. SF-36 scores were similar to those of the Greek population. The mean apnea-hypopnea index (AHI) was 11+/-14 events per hour, and the mean pulse oximetric saturation was 93.2+/-2.5%. According to AHI severity, they were divided into the following three groups: group 1, normal breathing function in sleep (n=19; AHI, <5 events per hour); group 2, mild OSA (n=20; AHI, 5.1 to 15 events per hour); group 3, moderate/severe OSA (n=11; AHI, >15 events per hour). The three groups differed in terms of BMI, and neck, waist, and hip circumferences. No difference was detected, though, in ESS and SF-36 scores. The majority of the Greek railway drivers are overweight and smokers. The most common reported symptom in the questionnaires is snoring, without significant daytime impairment, while sleep studies show a potentially higher prevalence of OSA. Democritus University of Thrace Identifier: 2979/5-2003. Union of the Greek Railway Drivers Identifier: 536/10-2003.

Restructuring the Greek Railways: Current Progress and Evaluation of Alternative Schemes

This paper presents the rationale, the method, and the alternative choices in the process of restructuring the Hellenic Railways Organisation (OSE). The most likely alternative structures regarding ownership and management issues of the new entities that will inherit the old OSE organization, and discusses the strategic implications of these alternatives are discussed. A critical view of the process of Greek railway reform and the evaluation results of the alternative organizational structures for the new situation are presented. It first presents the current experience in European Union and other countries of Europe, and the relative position of the Greek railways vis‐à‐vis the most common practices. The most likely options for the new organizational structure are presented which will result from the application of the European Union Directives and the Greek Law 2671/98 for the reorganization of the Greek railways. Based on a more detailed presentation of expected income and expenditures (i.e. economic viability) of the alternatives, a structure and a roadmap to these reforms is recommended for a successful and, above all ‘implementable’, reform of the Greek railways under the current conditions. Finally, the process for change and restructuring is described in terms of the basic principles and procedures that should be followed, and in terms of the necessary steps and procedures for the transition from the current to the new situation.

A factorial analysis for the determination of an optimal train speed with a desired ride comfort

A new method of optimization of the N MV is proposed. The comfort index N MV was measured and analyzed in research carried out for the Greek Railway network. Factorial analysis was used for the calculation of the effect of each factor on the comfort index N MV. ISO 2631-1 standards were also involved in this study for the design of the equivalent vibration dose lines as a function of the N MV and the exposure time. Using the factorial model, the N MV index for different values of a train’s speed and rail condition was predicted. Finally, an optimum speed value, as regards acceptable passenger comfort, was obtained by using the equal vibration dose lines.

A COMPARATIVE ANALYSIS OF THE FORECASTING ABILITY OF CLASSIC ECONOMETRIC AND FUZZY MODELS

The present paper analyzes the accuracy of forecasting ability that can be reached by the use of fuzzy techniques in comparison to classic econometric models. Following a brief presentation of the fuzzy technique, a revue of existing methods and models for forecasting rail passenger demand is presented. Based on data of rail passenger demand of Greek Railways, the parameters affecting demand are defined with the use of the appropriate statistical controls. Using these para-meters, econometric and fuzzy models are developed. The forecasting ability of each model and the reduction of ambiguity are checked as well as their range and application conditions.

Railroads in Greece: History, Characteristics, and Forecasts

Greece was relatively tardy in implementing a national rail network. The Greek Railways Organization (OSE) was formed in 1970 and united a number of regional railroads, some dating back to 1884. The current rail network in Greece has a length of approximately 2500 km with standard- and metric-gage tracks. Disadvantages of the network include a high percentage of single-line track, lack of homogeneity of track gage, inefficient alignment, absence of intermodal connections, and many at-grade intersections. Advantages include double tracks in a significant part of the Athens-Thessalonica axis that serves more than half of Greece’s population, improved operational controls, and popular intercity trains offering speedy service. Factors that affect railroad passenger and freight volumes include competition from airlines and motor carriers, gas prices, inflation, and the gross national product. These factors were used to estimate time-series models. Forecasts indicate increasing passenger demand and decreasing freight demand. OSE could provide a valuable and viable passenger service if cost-effective expenditures for improving it are possible. The future of freight operations is not hopeful. Additional emphasis may be placed on lines with historical and cultural significance. Further study is needed to assess the sustainability of forecasts vis-à-vis actual market shares and costs.

The influence of nonhomogeneous earth on the inductive interference caused to telecommunication cables by nearby AC electric traction lines

This work investigates the inductive interference caused by AC electric traction lines to nearby buried telecommunication cables, in the presence of a nonhomogeneous earth. The two dimensional, quasi stationary electromagnetic field diffusion equation has been numerically solved by using the finite element method (FEM), in a system involving an AC electric traction line of the Greek Railways Organization and a buried cable of the Greek Telecommunications Organization. Using FEM results, magnetic vector potential in the cross-section of the examined system, as well as the longitudinal electromotive force induced in the circuit formed by the telecommunication cable and earth, are calculated. A rigorous parametric analysis concerning various nonhomogeneous earth models has shown a significant influence of the depth and resistivity of the first earth layer, as well as of the resistivities of the different earth layers, on the electromagnetic field and on the inductive interference caused to the buried telecommunication cable.

Inductive interference caused to telecommunication cables by nearby AC electric traction lines. Measurements and FEM calculations

The paper investigates the inductive interference caused by AC electric traction lines to nearby buried telecommunication cables. Measurements according to the directives of the International Telecommunication Union (ITU) and calculations using the finite element method (FEM) are presented for a real system. This system consists of an AC electric traction line of the Greek Railways Organization and a buried cable of the Greek Telecommunications Organization. Finally, an analysis concerning the most important operational parameters in determining electric traction line influence is presented. Such parameters are the separation distance between the electric traction line and the buried telecommunication cable, the earth resistivity as well as the number and the material of the mitigation wires.

AN ASSESSMENT OF THE MANAGEMENT OF A RAILWAY ENTERPRISE FROM A MANAGEMENT CYBERNETICS PERSPECTIVE

A project was undertaken in order to identify structural and cultural causes of ineffectiveness in a state-owned railway enterprise. The methodology employed was based on Stafford Beer's Model of the Viable System. An “ethnographic type” preliminary study was undertaken, aiming at highlighting organizational problems from a management cybernetics perspective. Problems in the structuring of operational activities were diagnosed and reported in a previous publication (Paradissopoulos, 1991). This paper examines the structure and the functioning of the headquarters of the Greek Railway. The study demonstrates structural problems associated with a certain organizational culture. Being the outcome of both published material and the author's participation within the enterprise for more than ten years, the study reflects a subjective interpretation of organizational reality. It should therefore be supplemented by a survey within the enterprise, in order to derive the real dimensions of these problems from an analysis of managerial responses.