Accident Prediction Modeling Approaches for European Railway Level Crossing Safety

Safety is a core concern in the railway operation. Particularly, in Europe, level crossing (LX) safety is one of the most critical issues for railways. LX accidents often lead to fatalities and weighted injuries and seriously hamper railway safety reputation. Moreover, according to statistics, collisions between trains and motorized vehicles contribute most to LX accidents. With this in mind, we will elaborate on accident prediction modeling for train-vehicle collisions at LXs in this chapter. The methods and findings discussed in this chapter will offer an in-depth insight for interpreting significant aspects underlying collision occurrence and facilitate identifying technical countermeasures to improve LX safety

Advanced model-based risk reasoning on automatic railway level crossings

Safety is a core issue in the railway operation. In particular, as witnessed by accident/incident statistics, railway level crossing (LX) safety is one of the most critical points in railways. In the present paper, a Bayesian network (BN) based framework for causal reasoning related to risk analysis is proposed. It consists of a set of integrated stages, namely risk scenario definition, real field data collection and processing, BN model establishment and model performance validation. In particular, causal structural constraints are introduced to the framework forthe purpose of combining empirical knowledge with automatic learning approaches, thus to identify effective causalities and avoid inappropriate structural connections. Then, the proposed framework is applied to risk analysis of LX accidents in France. In details, the BN risk model is established on the basis of real field data and the model performance is validated. Moreover, forward and reverse inferences based on the BN risk model are performed to predict LX accident occurrence and quantify the contribution degree of various impacting factors respectively, so as to identify the riskiest factors. Besides, influence strength and sensitivity analyses are further carried out to scrutinize the influence strength of various causal factors on the LX accident occurrence likelihood and determine which factors the LX accident occurrence is most sensitive to. The main outputs of our study attest that the proposed framework is sound and effective in terms of risk reasoning analysis and offers significant insights on exploring practical recommendations to prevent LX accidents

Contribution à la Spécification et à la Vérification des Exigences Temporelles (Proposition d'une extension des SRS d'ERTMS niveau 2)

Les travaux développés dans cette thèse visent à assister le processus d ingénierie des exigences temporelles pour les systèmes complexes à contraintes de temps. Nos contributions portent sur trois volets : la spécification des exigences, la modélisation du comportement et la vérification. Pour le volet spécification, une nouvelle classification des exigences temporelles les plus communément utilisées a été proposée. Ensuite, afin de cadrer l utilisateur durant l expression des exigences, une grammaire de spécification à base de motifs prédéfinis en langage naturel est développée. Les exigences générées sont syntaxiquement précises et correctes quand elles sont prises individuellement, néanmoins cela ne garantie pas la cohérence de l ensemble des exigences exprimées. Ainsi, nous avons développé des mécanismes capables de détecter certains types d incohérences entre les exigences temporelles. Pour le volet modélisation du comportement, nous avons proposé un algorithme de transformation des state-machine avec des annotations temporelles en des automates temporisés. L idée étant de manipuler une notation assez intuitive et de générer automatiquement des modèles formels qui se prêtent à la vérification. Finalement, pour le volet vérification, nous avons adopté une technique de vérification à base d observateurs et qui repose sur le model-checking. Concrètement, nous avons élaboré une base de patterns d observation (ou observateurs) ; chacun des patterns développés est relatif à un type d exigence temporelle dans la nouvelle classification. Ainsi, la vérification est réduite à une analyse d accessibilité des états correspondants à la violation de l exigence associéeThe work developed in this thesis aims to assist the engineering process of temporal requirements for time-constrained complex systems. Our contributions concern three phases: the specification, the behaviour modelling and the verification. For the specification of temporal requirements, a new temporal properties typology taking into account all the common requirements one may meet when dealing with requirements specification, is introduced. Then, to facilitate the expression, we have proposed a structured English grammar. Nevertheless, even if each requirement taken individually is correct, we have no guarantee that a set of temporal properties one may express is consistent. Here we have proposed an algorithm based on graph theory techniques to check the consistency of temporal requirements sets. For the behaviour modelling, we have proposed an algorithm for transforming UML State Machine with time annotations into Timed Automata (TA). The idea is to allow the user manipulating a quite intuitive notation (UML SM diagramsduring the modelling phase and thereby, automatically generate formal models (TA) that could be used directly by the verification process. Finally, for the verification phase, we have adopted an observer-based technique. Actually, we have developed a repository of observation patterns where each pattern is relative to a particular temporal requirement class in our classification. Thereby, the verification process is reduced to a reachability analysis of the observers KO states relatives to the requirements violationVILLENEUVE D'ASCQ-ECLI (590092307) / SudocSudocFranceF

Towards safer level crossings: existing recommendations, new applicable technologies and a proposed simulation model

Every year,more than 400 people are killed in over 1,200 accidents at road-rail level crossings in the European Union. Together with tunnels and specific road black spots, level crossings have been identified as being a particular weak point in road infrastructure, seriously jeopardizing road safety. In the case of railway transport, level crossings can represent as much as 29% of all fatalities caused by railway operations. Up to now, the only effective solution appears to involve upgrading level crossing safety systems even though in more than 90% of cases the primary accident cause is inadequate or improper human behavior rather than any technical, rail-based issue. This article provides results of research done on possible technological solutions to reduce the number of accidents at level crossings and demonstrate the effectiveness of the latter. Elements of these recommendations and related research activities constitute the main focus of the research work described in this paper. It is organized as follows: In Section 2, we consider statistical data related to LX accidents in certain given European countries. These statistics as well as a European Commission Directive related to safety targets are analyzed and the main trends are drawn. The study was carried out on the basis of the classification by the European Railway Agency of active LXs and passive LXs. These results form the foundation for the work described in Section 3. Section 3 focuses on advanced technology to improve LXs safety. The main thrust of the study is to evaluate low-cost, standard technology that can contribute to a direct decrease in the number of accidents, at an affordable cost. Existing surveillance technologies already used in rail or road transport are first considered. To facilitate LX bimodality, special emphasis is put on technical solutions which have already demonstrated high efficiency in both environments. In Section 4, the mode of operation of each potential solution is modeled and evaluated considering several operational scenarii, in order to evaluate the aggregate benefits of all the input. Setting models to describe the dynamics surrounding the LX environment will prepare a basis to support the decision making process of a joint rail and road sector strategy on how to control LXs. Finally, section 5 brings the study to a close with a list of the main areas in which to concentrate our future work

Guest Editorial: Innovative control approaches for smart transportation systems

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Surveillance des systèmes à événements discrets à l'aide des réseaux de Petri temporels

Nous proposons une nouvelle approche de surveillance pour les SEDs qui permet d'exploiter le facteur temps dans un contexte d'observabilité partielle sur le comportement du système. Comme pour les principales approches de surveillance existantes, nous partons d'un modèle comportemental du système. Il s'agit ici d'un modèle de type réseau de Petri T-temporel (RdPT). Notre approche propose la construction d'un estimateur d'état à partir du graphe de classes d'état du système selon un algorithme que nous avons développé. L'estimateur, de par sa structure, met en évidence les conséquences perceptibles ou non de l'occurrence des différents scénarios évènementiels possibles dans le système. Un algorithme de suivi permet par ailleurs, en ligne, de vérifier la normalité du comportement et de retrouver les éventuelles défaillances qui peuvent se produire dans le système. Le dernier volet de notre étude concerne le développement de métamodèles UML pour la synthèse des relations fonctionnelles dans un système donné. L'objectif étant d'apporter une contribution dans une approche plus globale de construction de modèles pour la surveillance

IFAC CTS'2021, 16th IFAC Symposium On Control in Transportation Systems CTS, Lille, France, 8-10 juin 2021, Proceedings

The IFAC Symposium on Control in Transportation Systems (CTS'2021) was held in Lille from 8-10 June 2021 in a virtual form. This symposium is the 16th in the series of triennial symposia organized by the IFAC Technical Committee 7.4 on Transportation Systems. These symposia have a long tradition, starting in 1970 in Versailles, France, and continuing by taking place in several countries all over the world, with the last edition held in Savona, Italy, in 2018. This 16th symposium was organized by Université Gustave Eiffel, France. In total, 55 papers authored by 175 authors from 22 countries have been presented in the 12 regular sessions of the symposium covering numerous aspects related to the broad area of analysis, supervision, management, planning, and control of transportation systems. Besides the classic topics of this area, numerous contributions have addressed some hot topics related to artificial intelligence, connectivity and the use of formal methods for the engineering of transportation systems. The presentations of the accepted papers were made using pre-recorded videos prepared by the authors. However, Q&A sessions were scheduled after each presentation in an interactive form. Despite the fact some authors have to deal with the jet lag, almost all the corresponding authors were present during their sessions. About 120 people have joined the various symposium sessions which were very interactive with intensive interaction between the authors and the audienc

Formalizing a subset of ERTMS/ETCS specifications for verification purposes

ERTMS is the standard railway control-command and signaling system which aims to ensure railway interoperability throughout Europe while enhancing safety and competitiveness. ERTMS is composed of two main subsystems which include GSM-R, a radio system for enabling communication between the train and the traffic management center and ETCS, an automatic train protection system (ATP) to replace the existing national ATP systems. The ERTMS specifications are defined by means of standard documents which set out the requirements ensuring interoperability. These documents evolve regularly to give rise to successive versions. The ERTMS/ETCS standard defines different levels and operation modes according to various trackside and onboard setups and some operational conditions. Given the complexity and the high criticality of railway operation, verification and validation (V&V) are crucial tasks in railway application development. In this paper, after setting the background and the motivations, a mechanizable formalization of a subset of ERTMS/ETCS specifications relative to ETCS modes and transitions is developed. The present work aims to offer a readily available model for formal V&V. Using formal techniques to check SRS is highly recommended to tackle the complexity of the defined requirements and prevent specification errors. Model-checking technique, which is targeted here, offers exhaustive analysis of the system behavior based on its model and is highly automated, since it is supported by software tools. Based on the last available version of SRS specifications, a progressive process is undertaken to get a formal model which makes explicit the various modes characterized by their respective active functions, as well as the numerous combinations of conditions for switching between modes. The various steps guiding the translation of the SRS literal specifications into a formal model are explained. As will be shown through different examples, the obtained model is a convenient basis to check safety, interoperability and liveness properties

A Control Scheme for Automatic Level Crossings Under the ERTMS/ETCS Level 2/3 Operation

Level crossing (LC) safety is a crucial issue for railway operators and infrastructure managers. Accidents at LCs give rise to serious material and human damage, while seriously impacting the reputation of railway safety. In particular, some typical scenarios are behind the main part of train-car collisions which occur at LCs. On the other hand, ERTMS (European Rail Traffic Management System) is the standard railway control-command and signaling system being currently implemented throughout Europe and elsewhere. The aim is to ensure railway interoperability while enhancing safety and competitiveness of railway transportation. ERTMS specifications only provide a rough description when dealing with level crossing control. The present study elaborates on a functional control architecture for automatic LCs in the context of ERTMS operation Levels 2 and 3. Indeed, these operation levels ensure a continuous knowledge of train location thanks to the GSM-R (Global System for Mobile communications - Railways) link between the trains and the Radio Block Center (RBC). Hence, the established LC control scheme aims to ensure an optimal LC command based on the information regarding the train location and, thereby, prevent some potential risky scenarios and improve the global safety at LCs. To achieve this, a generic methodology is employed. Firstly, a formal behavioral model is developed using the Time Petri Net (TPN) notation. Then, the problem is formalized on the basis of the established TPN, in such a way as to carry out a sound and trustworthy analysis. The various steps of the developed approach are detailed and illustrated in the course of the paper. To the best of our knowledge, this is the first work that seeks to elaborate a control strategy of automatic LC in the ERTMS operation context