Abstract
In designing safety-critical infrastructures s.a. railway systems, engineers often have to deal with complex and large-scale designs. Formal methods can play an important role in helping automate various tasks. For railway designs formal methods have mainly been used to verify the safety of so-called interlockings through model checking, which deals with state change and rather complex properties, usually incurring considerable computational burden (e.g., the state-space explosion problem). In contrast, we focus on static infrastructure models, and are interested in checking requirements coming from design guidelines and regulations, as usually given by railway authorities or safety certification bodies. Our goal is to automate the tedious manual work that railway engineers do when ensuring compliance with regulations, through using software that is fast enough to do verification on-the-fly, thus being able to be included in the railway design tools, much like a compiler in an IDE. In consequence, this paper describes the integration into the railway design process of formal methods for automatically extracting railway models from the CAD railway designs and for describing relevant technical regulations and expert knowledge as properties to be checked on the models. We employ a variant of Datalog and use the standardized “railway markup language” railML as basis and exchange format for the formalization. We developed a prototype tool and integrated it in industrial railway CAD software, developed under the name RailCOMPLETE®. This on-the-fly verification tool is a help for the engineer while doing the designs, and is not a replacement to other more heavy-weight software like for doing interlocking verification or capacity analysis. Our tool, through the export into railML, can be easily integrated with these other tools. We apply our tool chain in a Norwegian railway project, the upgrade of the Arna railway station.
Highlights
Railway construction projects are heavy processes that integrate various fields, engineering disciplines, different companies, stakeholders, and regulatory bodies
With the purpose of increasing the degree of automation, we present results on integrating formal methods into the railway design process by the following means:
Whenever the user adds a symbol, its data editor is determined by the assigned class, and vice versa: when e.g. a railML object is imported into computer aided design (CAD), its corresponding symbol is inserted in the graphical model
Summary
Railway construction projects are heavy processes that integrate various fields, engineering disciplines, different companies, stakeholders, and regulatory bodies. We show the integration with existing railway engineering workflow by using CAD models directly This enables us to verify compliance with regulations continuously as the design process changes the station layout and interlocking. The approach presented in this paper could be applied to other engineering disciplines, such as catenary power lines, track works, and others, which have similar design regulations and often make use of a similar CAD environment.
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