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

Safety improvement of traffic at railway crossings

U ovom radu su istraženi statistički modeli za procenu frekvencije nesreća, težine posledica nesreća i empirijskog rizika koji najviše odgovaraju lokalnim karakteristikama putnih prelaza Srbiji u cilju identifikacije mesta visokog rizika na mreži. Uzorak putnih prelaza lociranih na železničkoj mreži u Srbiji je korišćen za istraživanje sa istorijskim podacima o nesrećama od pet godina. Korišćeni su modeli regresione analize (Puasonova regresija, Puasonov model sa viškom nula – ZIP, negativni binomni model – NB, NB model sa viškom nula – ZINB). Za modeliranje frekvencije nesreća najbolje se pokazao ZIP model. Kod modeliranja i procene težine posledica nesreća korišćen je multinomni logit model. Za modeliranje empirijskog rizika podacima najviše odgovara ZINB model. Identifikovane su promenljive koje su značajno povezane sa brojem i posledicama nesreća. Konačno, kalibrisani modeli zajedno sa dva kriterijuma za rangiranje koji su primenjeni u ovom radu su poslužili za identifikaciju putnih prelaza visokog rizika na mreži Železnica Srbije. Prvi kriterijum je srednji totalni rizik na putnom prelazu, a drugi kriterijum je procena rizika koja je zasnovana na srednjem empirijskom riziku. Prihvaćeni modeli frekvencije i posledica nesreća su poslužili za procenu redukcije nesreća na putnim prelazima primenom odgovarajućih tehničkih mera za podizanje nivoa bezbednosti. U tu svrhu urađena je sveobuhvatna analiza tehnologija i mera iz drugih regiona, a koje se danas primenjuju ili se ispituje njihova efikasnost. Koristeći njihova iskustva data je ocena efikasnosti koju bi te mere imale na putnim prelazima u Srbiji. U ovom radu vršeno je i neposredno istraživanje ponašanja vozača na putnom prelazu osiguranom drumskom signalizacijom, kao i nakon osiguranja istog putnog prelaza aktivnim sistemom. Ovaj prelazak sa jednog sistema osiguranja na drugi sistem bio je pogodan da bi se sprovelo istraživanje u cilju sagledavanja ponašanja vozača u dva različita sistema, kao i bezbednosnih efekata koji su proizašli iz toga.In this paper there were developed statistical models for estimation of accident frequency, accident severity and empirical risk, that correspond to local characteristics of crossings in Serbia. The goal was to identify high risk locations. The data used were from five year period. Several regression models were tried (Poisson regression, Zeroinflated Poisson – ZIP, negative binomial model – NB, Zero-inflated NB model – ZINB). The most suitable model for modeling accident frequency was ZIP model. For modeling accident severity multinomial logit model was used, whereas the best model for empirical risk was ZINB model. The variables significantly linked to accident frequency and severity were identified. Finally, the calibrated models together with two ranking criteria were used in order to indentify high risk crossings in Serbian railway network. The first criterion was mean total risk at a crossing, and the second one was based on mean empirical risk. The accepted models for accident frequency and severity were used for estimating the reduction of accidents at railway crossings applying the corresponding technical procedures for safety improvement. In order to accomplish this, there has been performed a complete analysis of technologies and procedures from various regions, which are used nowadays or are in phase of examining there efficency. Their results and experience were used to estimate the efficency that those procedures would have in Serbia. In this paper the drivers' behaviour on railway crossing was also studied, both with road signs and with active warining devices. This upgrade from one system to another was useful for examining drivers' behaviour in two different systems, as well as the safety effects that concequently appeared

Assessing the effectiveness of technical measure on Serbian railway crossings

In this paper numerical example are provided to evaluate countermeasure at selected crossings in Serbia. In this way will be shown how the developed statistical models for estimation of Accident Frequency and Accident Severity on Serbian railway crossings can be used to assess the effects of the measures that would be used for a particular crossing

A Novel Entropy-Fuzzy PIPRECIA-DEA Model for Safety Evaluation of Railway Traffic

The conditions of globalization often dictate the functioning of transport markets, so it is necessary to conduct frequent research in order to achieve sustainable business. This is achieved through adequate risk and safety management at all levels. The research carried out in this paper includes determining the state of railway traffic safety in a total of nine railway sections in Bosnia and Herzegovina (B&H). The aim of this paper is to develop a new integrated Entropy-Fuzzy PIPRECIA (PIvot Pairwise RElative Criteria Importance Assessment)-DEA (Data Envelopment Analysis) model for determining the state of safety in B&H under particular conditions of uncertainty. Additionally, the aim is to combine the advantages of linear programming (DEA), an objective method (Entropy), and a subjective method (Fuzzy PIPRECIA). In this way, an integrated objective–subjective model is created that provides accurate and balanced decision-making through their integration. Eleven sustainable criteria were defined and divided into six inputs and five outputs. The Entropy model was used to determine the weight values of the inputs, while due to the nature of the outputs, Fuzzy PIPRECIA was used to evaluate them. After the application of the two methods, the way of averaging their values was defined. The DEA model, which implies an input- and output-oriented model, was applied to determine which railway sections have satisfactory performance in terms of safety. Two sections were eliminated from further computation due to extremely poor performance and high risk. Then, the weighted overall efficiency ranking method was applied to determine the final ranking of the railway sections. The results obtained were verified through a sensitivity analysis, which involved changing the impact of the five most significant criteria and a comparison with two Multi-Criteria Decision-Making (MCDM) methods

Locomotive Assignment Optimization Including Train Delays

Intention– Cyclic locomotive assignment planning is a specific type of organization of locomotive usage, and in fact, it means putting the complete workload to a closed chain, which is repeated periodically. The concept of cyclic locomotive assignment planning type organization in the area of train traction has proven in practice as the best one, but as it is made for in-advance defined timetable and without considering the stochastic nature of the timetable realization process, it leads to incompatibility in using locomotives. Methodology – Methodology defined in this paper contains: research of train delays on the Serbian Railways and Montenegrin Railways networks, analysis of the real system organization of locomotive usage in conditions of train delays, theoretical thesis of solving the problem of optimal cyclic locomotive assignment planning in conditions of train delays, designing of a model with algorithms, preparing the software package, testing the model and program with results, as well as the conclusions drawn from the complete research project. Results– The optimization model of cyclic locomotive assignment planning during the process of making timetable including train delays has been defined. Conclusion –The obtained results have shown as expected, that the larger delays of trains required a larger number of locomotives. However, by using this model it is possible to optimize the required number of locomotives, taking into account the real time delays of trains

Study of Drivers’ Behaviour at a Passive Railway Crossing

Problem: The number of killed and injured persons in incidents at railway level crossings is generally increasing on the Serbian Railways, particularly at passive crossings. In this paper we researched the direct behaviour of road traffic participants at a conventional railway passive crossing. Method: Direct observational study of drivers’ behaviour at a level crossing. Results: Sixty-one road vehicle drivers were observed in the moments of train approach. The probability of crossing varies depending on the train distance and the time the driver has to cross the crossing. The drivers who have limited visibility cannot estimate the speed of the approaching train well and make more risky decisions. Conclusion: This study shows that the number of “risky crossings” is worrying as the result of such crossings is a large number of accidents with fatal consequences at the passive crossings in Serbia