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

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

A Diagnosis Study on a Train Passenger Access System using Petri Net Models

CTS 2018, 15th IFAC Symposium on Control in Transportation Systems, Savona, ITALIE, 06-/06/2018 - 08/06/2018In this paper, we conduct a diagnosis analysis of the passenger access system, while considering a high level abstraction perspective that allows for adapting discrete event models to represent the system behavior. Firstly, we establish Petri net behavioral models for the global system functions, including the nominal operating mode and various faulty behaviors. Then, based on the established Petri net models, a diagnoser-based approach is brought into play to investigate the diagnosability of the system regarding the different predetermined classes of failures

A µ calculus formulation of the diagnosability of discrete event systems

Diagnosis is a crucial task in safety critical systems. In particular, diagnosability is the property ensuring that any failure can be determined within a finite delay. Early works on diagnosability of discrete event systems (DES) establish intermediary models from the analysed model and then call specific procedures to check diagnosablity based on these models, while some recent works try to give a diagnosability formulation as a model-checking problem. The present work attempts to contribute to this trend by developing a single framework able to handle both of the diagnosability issues: how to model the problem? and how to decide it? Namely, a generic operative formulation of diagnosability using the µ-calculus logic is established, which allows resolving the diagnosability issue within a single formalism. We also show how the developed formulation can be extended to deal with further diagnosability issues. Besides, using the same formulation, an online diagnosis algorithm is developed

Using Model-Checking Techniques for Diagnosability Analysis of Intermittent Faults-A Railway Case-Study.

VECOS 2016 - 10th International Workshop on Verification and Evaluation of Computer and Communication Systems, Tunis, TUNISIE, 06-/10/2016 - 07/10/2016This paper addresses formal verification of intermittent fault diagnosability in Discrete Event Systems (DESs). The system is modeled by a Finite State Automaton and intermittent faults are defined as faults that can automatically recover once they have occurred. Two definitions of diagnosability, regarding the detection of fault occurrences within a finite delay and the detection of fault occurrences before their recovery, are discussed. The diagnosability is analyzed on the basis of the twin-plant structure, which is formally modeled as a Kripke structure, while diagnosability conditions are formulated using LTL temporal logic. We focus on a practical application of this approach, namely a case-study from the railway control field, will serve as a benchmark to illustrate the various developed mechanisms and to assess the scalability of the technique

Diagnosability Analysis of Intermittent Faults in Discrete Event Systems Using a Twin-plant Structure

Most research in fault diagnosis of discrete event systems has been focused on permanent failures. However, experience with monitoring of dynamic systems shows that intermittent faults are predominant, and that their diagnosis constitutes one of the most challenging tasks for surveillance activities. Among the main existing approaches to deal with permanent faults, two were widely investigated while considering different settings: the Diagnoser based approach, and the Twin-plant based approach. The latter was developed to cope with some complexity limitations of the former. In the present paper, we propose a twin-plant based approach to deal with diagnosability of intermittent faults. Firstly, we discuss various notions of diagnosability, while considering the occurrence of faults, their recovery, and the identification of the system status. Then, we establish the necessary and sufficient conditions for each notion, and develop on-the-fly algorithms to check these properties. The discussed approach is implemented in a prototype tool that is used to conduct experiments on a railway control benchmark