This conference paper discusses a new analytical approach to the evaluation of traffic safety at the railway crossings. The new method is based on the use of ontological principles. The ontological tools present a comprehensive decision-making tool, will can be applied to any potential hazardous railway crossing on a road or rail network. The ontology can be considered as a knowledge base that not only stores the data itself, but also defines the relationships between these data, and can therefore be described as a clearly suitable tool for describing risks at level crossings

Kocián, Karel

Kohout, Tomáš

Nouzovský, Luboš

Vrtal, Pavel

English

CTU Open Journal Systems (Czech Technical University, Prague / České vysoké učení technické v Praze)

https://doi.org/10.14311/APP.2023.43.0057Acta Polytechnica CTU Proceedings 43:57–61, 2023 © 2023 The Author(s). Licensed under a CC-BY 4.0 licencePublished by the Czech Technical University in PragueAPPLICATION OF ONTOLOGY/CONCEPTUAL MODELLING INTHE CONTEXT OF RISK IDENTIFICATION AT LEVEL CROSSINGSTomáš Kohout∗, Luboš Nouzovský, Pavel Vrtal, Karel KociánCzech Technical University in Prague, Faculty of Mechanical Engineering, Department of Forensic Experts inTransportation, Konviktská 20, 110 00 Prague, Czech Republic∗ corresponding author: kohout@fd.cvut.czAbstract. This conference paper discusses a new analytical approach to the evaluation of trafficsafety at the railway crossings. The new method is based on the use of ontological principles. Theontological tools present a comprehensive decision-making tool, will can be applied to any potentialhazardous railway crossing on a road or rail network. The ontology can be considered as a knowledgebase that not only stores the data itself, but also defines the relationships between these data, and cantherefore be described as a clearly suitable tool for describing risks at level crossings.Keywords: Level crossing, traffic safety, ontology, data utilisation.1. IntroductionSafety analysis, or risk analysis, is a topic that res-onates across many different disciplines. Transportsafety analysis is no exception. If we look at a partic-ular area of transport as an interrelated and influenc-ing system, it is necessary to address the question ofwhether the system is working properly and indicatesan adequate level of safety not only for the systemas a whole but also in relation to its users. The is-sue of safety analysis is closely related to the issueof collecting, processing, evaluating and interpretingdata that affect the safety level of a particular system.Given the considerable amount of measurable datathat the modern world makes possible through tech-nology nowadays, it is important to work effectivelywith this data. The approach of how to store thedata is also an important factor. Currently, simpletools such as MS EXCEL are used for these purposes.However, it is questionable whether this approach iseffective in relation to subsequent analyses, creates arealistic view of the analyzed system and satisfies theneeds of subsequent complex analyses over these data.At the same time, it is important to ensure the highestpossible standardisation of procedures in these analy-ses in the context of minimising the potential impactof analysts’ subjective assessments on the risk analysisoutputs. The aim of this systems approach to safetyanalysis is to increase the informative value of thedata at all stages of the analysis and risk classificationof a particular system.2. Conceptual modelling,ontologyConceptual modelling allows you to create a model ofa real part of the world. The basis of this modelling isan ontology that guarantees the correct interpretationof all terms. A conceptual model is created by synthe-sizing a theoretical knowledge base and an appropriatetool. In this context, the theory is represented by anontology and a graphical modelling language is usedas a tool. The ontology, unanimously defines termsand relationships between terms in the specific realitydomain described for which the ontology is created.In general, an ontology is a tool for capturing thereal world, or parts of it, in the form of standardizingand formalizing the meaning of concepts in the de-scribed part of the world. For this reason, ontologiescan be beneficially used in modelling, questioning orderivation tasks [1–3].2.1. Conceptual modellingConceptual modelling can also be defined as concep-tual modelling. Conceptual modelling allows mod-elling of real world elements. A conceptual model isrealized by combining a theoretical knowledge baseand a suitable tool. The theory is represented by anontology, which uniquely defines terms and relation-ships between terms from the specific reality domaindescribed for which it is created, and a graphical mod-elling language is used as the modelling tool. Anexample of this is the Unified Modelling Language(UML). Conceptual modelling is based on modellingthe real world domain by using Entities and Rela-tionships between these parameters. The term Entitycan be used to imagine a real world object capable ofindependent existence and is uniquely distinguishablefrom other Entities. The notion of Relationship spec-ifies the relations between Entities and at the sametime describes certain properties. An important termis the notion of Attribute, which indicates a prop-erty of Entities or Relationships. The Figure 1 showsgraphically the relationship between the ontology thatgives a clear meaning to the conceptual model, theconceptual model that can be described by the UMLmodelling language and this specific modelling lan-guage. In general, it can be assumed that conceptualmodelling represents the initial phase of the analy-57T. Kohout, L. Nouzovský, P. Vrtal, K. Kocián Acta Polytechnica CTU ProceedingsFigure 1. The relation between conceptual model,ontology and UML modelling language.sis. The next phases are the proposal of the logicalmodel and the implementation within the physicalmodel [1, 4–6].2.2. Unified Foundational OntologyThe foundations of Unified Foundational Ontology(UFO) were specified by Giancarlo Guizzardi in hisPhD thesis. UFO is currently being further developedby the NEMO research group of which Giancarlo Guiz-zardi is a part. It is a universal upper-level ontologythat can be used for application to any part of thereal world. The UFO ontology is further divided intothe following three interrelated units:(1.) UFO-A deals with individual aspects of reality,which are considered to be individual objects, so-called endurants. UFO-A has been used to anal-yse structural constructs of conceptual modelling,such as object types and taxonomic relations, asso-ciations and relations between associations, roles,properties, data types and weak entities, and par-ticipation relations between objects.(2.) UFO-B is a part of the ontology, which extendsthe original UFO-A ontology by dynamic processand events called perdurants, which are varyingdepending on time.(3.) UFO-C extends the UFO-B ontology and dealswith social aspects. By this term we can imagineaspects that are e.g. faith, actions or social roles [1,3, 7].2.2.1. OntoUMLOntoUML is an ontology language for ontological con-ceptual modeling. OntoUML is an extension of theUML language and is based on the UFO ontology. Thefoundations of UFO and OntoUML are based on Gian-carlo Guizzardi’s PhD thesis “Ontological foundationsfor structural conceptual models” [1]. In his thesis,Guizzardi proposed a new fundamental ontology forconceptual modeling (UFO) and used it to evaluateand redesign the UML for the purpose of conceptualmodeling and domain ontology engineering (see theFigure 2) [2].3. Motivation for Applying atLevel CrossingsThe following section discusses the evaluation of theaccident rate at level crossings in the Czech Republic.The input dataset represents accidents that occurredat level crossings between 2010 and 2020. For this pe-riod, the Railway Inspectorate of the Czech Republicrecorded a total of 2 182 accidents in which 1 116 per-sons were injured and 430 were killed. The Figure 3shows the evolution of the number of accidents andtheir consequences at level crossings over the 12-yearperiod. Considering the evolution of the number ofaccidents, no decreasing trend can be identified be-tween 2011 and 2021. The number of injured personsalso shows a decreasing trend, which can be classifiedas a rather fluctuating trend over the period analysed.The most important indicator, namely the numberof persons killed, does not follow a decreasing trendeither, except for the last year analysed, 2021 [8, 9].The Figure 4 shows the evolution of the number ofaccidents at level crossings by type of signalling system.It can be deducted from the number of incidents thatlevel crossings protected only by a traffic sign have analmost similar absolute accident rate as level crossingsequipped with a level crossing signalling system withlight signals without barriers. However, taking into ac-count the ratio between the number of level crossingsprotected only by a traffic sign (3 486 pcs) and the num-ber of level crossings equipped with a signalling systemwith light signalling without barriers (2 363 pcs), itcan be reasonably stated that the relative accidentrate is higher and therefore the safety level is lowerfor level crossings equipped with a signalling systemwith light signalling without barriers [8, 9].The mentioned negative statistical evaluation of thelevel of safety at level crossings equipped with levelcrossing signalling system with light signals withoutbarriers is clearly confirmed by the statistics sum-marised in the Figure 5. The figure shows the evo-lution of the number of persons killed in accidentsat level crossings according to the type of signallingsystem. In the period under review, a total of 210persons were killed at level crossings protected by levelcrossing signalling system with light signals withoutbarriers, which is three times higher than the numberof persons killed at level crossings protected only bytraffic sign [8, 9].To summarise this section, based on statistical dataon the number of incidents at level crossings and theirconsequences, an unsatisfying development trend canbe stated. In general, there is no significant year-on-year decreasing trend in the number of accidentsor the number of persons injured or killed. Alsoalarming is the negative assessment of the safety levelof level crossings with signalling system with trafficlights without barriers. In terms of both relative and58vol. 43/2023 Application of Ontology/Conceptual Modelling in the Context of Risk IdentificationFigure 2. OntoUML metamodel [2].59T. Kohout, L. Nouzovský, P. Vrtal, K. Kocián Acta Polytechnica CTU ProceedingsFigure 3. Evolution of the number of accidents atlevel crossings [9].Figure 4. Evolution of the number of accidents atlevel crossings by type of protection [9].absolute accident rates, this type of protection posesthe greatest risk for road users. The above conclusionsof the analysis of the level of safety at level crossingsin the Czech Republic clearly indicate a necessity fora more detailed analysis of the presented issues inorder to achieve a socially acceptable level of safetyof traffic on roads in accordance with the Europeantransport policy and the national road safety strategy.Research by the author of this article focuses onsolving this problem. A number of interacting param-eters have a direct or indirect influence on the issue ofrisk analysis at level crossings. For this reason, orga-nizing these parameters by creating an ontology seemsto be effective in terms of subsequent safety analy-ses. At the same time, this method limits possiblemisinterpretation of individual terms or relationshipsbetween terms.4. Practical ApplicationA fundamental premise for assessing the risk of levelcrossings is a comprehensive approach, both in termsof defects of the road and the railway infrastructure.The safety of a level crossing is determined by theprobability of occurrence of risks. The potential occur-rence of an incident is influenced by the parametersby which the level crossing and its surroundings aredescribed. The main influence on the level of safetyis the current qualitative state of the specified param-eters. It is essential to reflect that the parameters areinterdependent within a single system (level crossing)and influence each other. Generally, situations areconsidered to be at risk when a level crossing is in aFigure 5. Evolution of the number of persons killed inaccidents at level crossings by type of protection [9].state where a risk condition is identified for severalspecific parameters.Specifically, the following set of parameters in Ta-ble 1 has been defined that influence the level of riskat level crossings. The following defined parametersdescribe the level crossing in detail in terms of threespecific groups of defined parameters. It is a groupof parameters belonging to the road and a group ofparameters parametrizing the railway segment of theissues. The last group of parameters contains thoseparameters that cannot be clearly classified into one ofthe two above-mentioned categories but are necessaryfor the completion of the complex parameterisationof the level crossing.If we consider the ontology as a unified knowledgebase that not only stores the data itself, but alsodefines the relationships between these data, it canbe described as a clearly suitable tool to describe therisks at level crossings.5. DiscussionThe next steps in the project are the validation ofthe model based on ontological principles within atest database of selected level crossings. At the sametime, a database of appropriate remediation measuresis being created to be addressed to the identified risks.The main potential problem of the research is thelimited scope of literature and information sourcesabout the issue. Unified Foundational Ontology isvery well described in Dr. Guizzardi’s dissertation.However, there are few practical examples or examplesof work dealing with ontologies UFO-B and UFO-C.6. ConclusionThe perspective and effectiveness of this project con-sists primarily in the development of a unified decision-making tool for a comprehensive evaluation of thelevel of traffic safety at level crossings. The result-ing determination of the risk level of individual levelcrossings will be based on the proposed and validatedontological model. This ontological model will be com-plemented by the knowledge base of the researcherregarding the risk rating of individual parameters, ora combination of interrelated parameters if they arein an inadequate state.60vol. 43/2023 Application of Ontology/Conceptual Modelling in the Context of Risk IdentificationRail Road OthersIntensity of rail transport Road traffic intensity Number of accidentsImportance of the railway Road category Railway crossing angleNumber of tracks Speed limit Location – urban/rural areaLine speed Layout of the road Assessment of obstacles inthe clearance zoneLevel of protection Vertical curvature of the roadLayout of the railway Technical condition of traffic signsValidity of the regulation S 4/3 Perceptibility of the level crossingType of railway signalling sys-temVariability of the road widthTechnical condition of crossing roadPossibility of glareDistance between level crossing and intersec-tionPerceptibility of traffic signsWalking route across level crossingTable 1. List of defined parameters.In parallel with the identification of traffic safetydefects, a database of specific appropriate remedialmeasures is being created. These measures appropri-ately address the identified traffic safety risks. In thecase of practical implementation of this clearly definedmethodological approach to the evaluation of risks re-lated to level crossings and the design of appropriateremediation measures, a socially acceptable level oftransport safety at level crossings will be ensured.AcknowledgementsThis work was supported by the Grant Agency ofthe Czech Technical University in Prague, grant No.SGS21/137/OHK2/2T/16, No. SGS21/138/OHK2/2T/16and No. SGS20/199/OHK2/3T/16.References[1] G. Guizzardi. Ontological foundations for structuralconceptual models. Ph.D. Thesis, University of Twente,Netherlands, 2005.[2] OntoUML Community Portal. 2017, [2022-04-20],https://ontouml.org/.[3] G. Guizzardi, G. Wagner. Using the unifiedfoundational ontology (UFO) as a foundation for generalconceptual modeling languages. Theory and Applicationsof Ontology: Computer Applications pp. 175–196, 2010.https://doi.org/10.1007/978-90-481-8847-5_8[4] J. Arlow. UML and the unified applicationdevelopment process. Neustadt Ila, 2003.[5] M. Molhanec. Ontology and conceptual modelling (ashort introduction). [2022-04-20],https://www.slideserve.com/noura/ontologie-a-konceptu-ln-modelov-n-stru-n-vod.[6] M. Molhanec. Conceptual modelling, formalfoundations and ontologies. [2022-04-20], http://prog-story.technicalmuseum.cz/images/dokumenty/Programovani-TSW-1975-2014/2006/2006-17.pdf.[7] Nemo. [2022-04-22],https://nemo.inf.ufes.br/en/projetos/ufo/.[8] QCM, s.r.o. In 2021, the fewest people died onrailways in 19 years. [2022-04-20],http://www.dicr.cz/v-roce-2021-zemrelo-na-drahach-nejmene-osob-za-poslednich-19.[9] Railway Administration, State organization. Levelcrossings in numbers. [2022-04-20], https://www.spravazeleznic.cz/o-nas/bezpecna-zeleznice/bezpecnost-na-prejezdech/prejezdy-v-cislech.61

Application of ontology/conceptual modelling in the context of risk identification at level crossings

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Application of ontology/conceptual modelling in the context of risk identification at level crossings

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