Methodology to determine a railway junction optimal design

Simulaciono modeliranje je veoma efikasan alat za analiziranje složenih železničkih sistema kao što su sistemi saobraćaja vozova na rasputnici. Rasputnica je službeno mesto gde se sa otvorene pruge odvaja druga pruga. Model sistema rasputnice predstavlja procese kretanja vozova preko izolovanih odseka sistema rasputnica. Granice modela postavljaju se u stanicama koje okružuju rasputnicu. Model Petrijevih mreža sistema rasputnice razvijen je tako da je svaka vrsta odseka predstavljena modulom (podsistemom) u grafu Petrijevih mreža. Izrada modela sistema rasputnice vrši se povezivanjem modula odseka po planu odseka, a zatim i njihovim obeležavanjem i definisanjem. Ulazni podaci potrebni za izvršenje simulacije, definišu se u bazi podataka koja je povezana sa simulacionim programom. Ulazni podaci o primarnom kašnjenju vozova generišu se u posebnom modelu ili modulu fazi Petrijeve mreže. Modeli kašnjenja vozova zasnivaju se na tehnikama računarske inteligencije. U slučaju kada postoje statistički podaci o prethodnim kašnjenjima, za proračune kašnjenja koriste se modeli zasnovani na neuronskim mrežama ili adaptivni neuro-fazi modeli. Ovi modeli se obučavaju i verifikuju podacima koji dobijenim praćenjem kretanja vozova i iz dnevnika otpravnika vozova. Kada nisu dostupni podaci o kašnjenju vozova u prethodnom periodu, primenjuje se model zasnovan na fazi logici, gde se ekspertsko znanje o ponašanju sistema koristi za kreiranje modela. U toku izvršenja simulacije, podaci o kretanju voza i zauzetosti odseka snimaju se u unapred definisanu bazu podataka. Stanja odseka i kretanje vozova tokom simulacije može se pratiti pomoću animacije i grafikona saobraćaja vozova. Baza podataka u kojoj se nalaze rezultati simulacije prilagođena je za jednostavnu obradu podataka i analizu rezultata. Model je testiran na primeru rasputnice „G“ beogradskog železničkog čvora. Nakon izrade, validacije i verifikacije modela rasputnice „G“, analizirani su rezultati modela preko sekundarnih kašnjenja vozova nastalih u sistemu rasputnice. Takođe, upoređena su različita infrastrukturna rešenja rasputnice...Simulation modelling is very efficient method for analysis of complex railway systems like railway junction system. Junction is a place on the track where another track diverges. Model of the junction system is comprised of the processes of train movement on insolated sections. Model boundaries are stations that are surrounding the junction system. Petri Net model of the junction system is defined as a model where all types of section blocks are denoted by a module or subsystem in the Petri Nets Graph. Building of the model is a process of connecting modules according to the junction section plan and then marking and defining them. Initial data for simulation is located in an external database connected to the simulation program. Input data on train primary delay is calculated either in separate model or in the fuzzy Petri net module. Models for calculating train primary delay are based on computational intelligence techniques. When there are historical data on train delays, primary delays are calculated by neural networks or adaptive neuro-fuzzy model. These models are trained and verified by data on previous train delays (from train detection systems or from dispatcher’s logs). When there are no data on previous delays in system, delays are calculated by a fuzzy logic model where experts’ knowledge on system behaviour is used to create a model. During simulation run data is exported to external predefined database. State of the sections and train movements are observed in animation window and in the trains’ time-distance graph. Database of simulation results is improved for data query and data analysis. Model is tested on a case study of junction “G” system located in Belgrade Railway Node. After model building, validation and verification of model, data results of simulation are analysed by secondary delays generated within the model. Also, different infrastructure solutions are compared..

Simulating Train Dispatching Logic with High-Level Petri Nets

Railway simulation is commonly used as a tool for planning and analysis of railway traffic in operational, tactical and strategical level. During the simulation, a typical problem is a deadlock, i.e. a specific composition of trains on a simulated section positioned in such a way that they are blocking each other\u27s paths. Deadlock avoidance is very important in the simulation of railways because deadlock can stop the simulation, and significantly affect the simulation results. Simulation of train movements on a single track line requires implantation of additional rules and principles of train spacing and movement as train paths are more often in conflict than on a double track line. A High-level Petri Nets simulation model that detects and manages train path conflicts on a single track railway line is presented. Module for train management is connected to other modules on a hierarchical High-level Petri net. The model was tested on a busy single track mainline between Hrpelje-Kozina and Koper in south-western Slovenia

A Two-Phase VIKOR Model for Track Layout Evaluation of Passenger Rail Stations

Passenger stations are transit hubs where several railway lines interchange. They have important roles in providing train operations and passenger services. Interrelations between track layouts and technological performances are important for reducing bottleneck effects and raising the operational effectiveness of rail networks. To the best of our knowledge, in previous research the assessment of track layouts has not been considered with respect to various technological aspects including railway operations, safety, and passenger services but rather as a single criterion for analysis of different individual performance indicators. We propose a new two-phase decision making approach for the complex evaluation of track layout alternatives. The first phase model is a VIKOR method for ranking track layouts by criteria related to: railway capacity, safety issue, and passenger-pedestrian fluctuations. Next, in the second phase, we use marginal analysis to find Pareto front and compare the alternatives ratings by calculating performance-benefit coefficients. To show the applicability of the proposed model, we employ an illustrative example of a passenger rail station and evaluate six different track layout alternatives. The effectiveness of the proposed model is demonstrated comparing the proposed two-phase model with traditional VIKOR

A Threshold Policy for Dispatching Vehicles in Demand-responsive Transit Systems

This paper considers vehicle dispatching for a flexible transit system providing doorstep services from a terminal. The problem is tackled with an easy-to-implement threshold policy, where an available vehicle is dispatched when the number of boarded passengers reaches or exceeds a certain threshold. A simulation-based approach is applied to find the threshold that minimizes the expected system-wide cost. Results show that the optimal threshold is a function of demand, which is commonly stochastic and time-varying. Consequently, the dispatching threshold should be adjusted for different times of the day. In addition, the simulation-based approach is used to simultaneously adjust dispatching threshold and fleet size. The proposed approach is the first work to analyse threshold dispatching policy. It could be used to help improve efficiency of flexible transit systems, and thereby make this sustainable travel mode more economical and appealing to users.</p

Model for Railway Infrastructure Management Organization

The provision of appropriate quality rail services has an important role in terms of railway infrastructure: quality of infrastructure maintenance, regulation of railway traffic, line capacity, speed, safety, train station organization, the allowable lines load and other infrastructure parameters.The analysis of experiences in transforming the railway systems points to the conclusion that there is no unique solution in terms of choice for institutional rail infrastructure management modes, although more than nineteen years have passed from the beginning of the implementation of the Directive 91/440/EEC. Depending on the approach to the process of restructuring the national railway company, adopted regulations and caution in its implementation, the existence or absence of a clearly defined transport strategy, the willingness to liberalize the transport market, there are several different ways for institutional management of railway infrastructure.A hybrid model for selection of modes of institutional rail infrastructure management was developed based on the theory of artificial intelligence, theory of fuzzy sets and theory of multicriteria optimization.KEY WORDSmanagement, railway infrastructure, organizational structure, hybrid model</p

(Middle Class) Mass Housing in Serbia Within and Beyond the Shifting Frames of Socialist Modernisation

In many aspects middle-class mass housing development in Serbia/Yugoslavia was unprecedented, determined by a growing and unacknowledged formation of a middle class in the context of Yugoslav socialism, and a widely proclaimed but elusive social ideal of “housing for all”. Two types of MCMH were the most prevalent in the period considered here (1945-1991): a multi-storey collective residential building, in or outside the city centre, and the individual private house, built in formal and informal or so-cold “wild”settlements. The Yugoslav housing experiment emerged mostly within the collective residential estates. The appropriation, innovation and even invention of different industrial building methods was further enhanced by excellent standards in urban planning and architectural design, exemplified in this study by selected MCMH cases in New Belgrade, Novi Sad, Bor and Subotica. Due to aging, lack of maintenance and the impoverishment of its inhabitants, the present state of this large housing stock is poor, its future uncertain, and yet, its lessons are of vital importance today. In response to what would be the lessons and contemporary implications of the Yugoslav housing experience, in this brief review we have outlined the specificities and the unique historical conditions of the emergence of middle class mass housing in Serbia.This publication is based upon work from COST Action “European Middle-Class Mass Housing” CA18137 supported by COST (European Cooperation in Science and Technology)

Planning Dial-a-Ride Services Statistical and Meta-Modeling Approach

Accessibility of public transit is an important political and social objective for transit agencies across the world. To meet this objective, many transit agencies provide a specialized door-to-door transportation service, called dial-a-ride (DAR), for the elderly and disabled. Annual DAR ridership growth exceeding 5% is reported in many cities in the United States, and this trend is expected to continue because of the aging population. In response to increased ridership, DAR services have become the fastest growing fraction of many transit agency budgets. These trends motivate the development of models that support decision making in the planning of new DAR systems or expansion of existing systems. Several statistical models have been developed in the past decade that can be used to determine the necessary DAR system capacity. These models focus on peak period analyses and provide good fit when applied to simulated case studies. This study aimed to demonstrate the importance of considering the entire day of operations rather than only the peak period. Several factors were identified that have been omitted in the literature, and comprehensive statistical and meta-models were developed for determining DAR system capacity. The performance of two proposed models was assessed with real-world data from a DAR service. The proposed models are available to the general public through a web system that provides free decision support to practitioners involved in designing DAR systems

Advanced evaluation of simultaneous train formation methods based on fuzzy compromise programing

Multi-group trains have potential to take a substantial segment in realizing wagonload services. Multi-group train formation is a complex marshalling procedure which composes a train by sorting wagons according to their destinations. The order of wagons corresponds to the disposition of destinations on the train route. The determination of rational sorting schedules should be based on a comprehensive approach addressing different quantitative and qualitative indicators which are conflicting and uncertain. In order to address these conditions, we proposed a new approach for fuzzy multi-criteria evaluation of simultaneous train formation methods. In this paper we evaluate simultaneous train formation methods and provide recommendations for the rational application of elementary, triangular and geometric sorting schedules regarding different scales of sorting task complexity

Analyzing passenger train arrival delays with support vector regression

We propose machine learning models that capture the relation between passenger train arrival delays and various characteristics of a railway system. Such models can be used at the tactical level to evaluate effects of various changes in a railway system on train delays. We present the first application of support vector regression in the analysis of train delays and compare its performance with the artificial neural networks which have been commonly used for such problems. Statistical comparison of the two models indicates that the support vector regression outperforms the artificial neural networks. Data for this analysis are collected from Serbian Railways and include expert opinions about the influence of infrastructure along different routes on train arrival delays