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PROCEEDINGS OF THE FIFTH INTERNATIONAL CONFERENCE ON RAILWAY TECHNOLOGY: RESEARCH, DEVELOPMENT AND MAINTENANCE
Edited by: J. Pombo
Automated Railway Interlocking Plan Verification Using Petri Nets
B. Farkas1 and T. Bartha1,2
1Department of Control for Transportation and Vehicle Systems, Faculty of Transportation Engineering and Vehicle Engineering, Budapest University of Technology and Economics, Hungary
B. Farkas, T. Bartha, "Automated Railway Interlocking Plan Verification Using Petri Nets", in J. Pombo, (Editor), "Proceedings of the Fifth International Conference on Railway Technology: Research, Development and Maintenance", Civil-Comp Press, Edinburgh, UK, Online volume: CCC 1, Paper 15.7, 2022, doi:10.4203/ccc.1.15.7
Keywords: railway interlocking, railway topology modelling, route control table, formal methods, Petri nets, T-invariants.
The efficiency and safety of rail transport are ensured by interlocking systems. In the areas controlled by interlocking systems, trains can only run on locked routes. Route control tables made by plan engineers include all the routes and the related safety conditions for a given station layout. The preparation process of railway interlocking plans is still mostly done manually, but it is supported by several tools. For the verification of completed plans, there is no established, systematic methodology yet. In our paper, we define the planning process steps. The first step is route identification, for which we developed a Petri net based method. The solution can be derived from the structural properties of a specially crafted Petri net, in particular its T-invariants. The station topology can be decomposed into elementary objects, each of which can be modelled by corresponding Petri net fragments. We demonstrate our method for the identification of routes in a case study. The paper describes the models of objects defined for track elements and the Petri net constructed from them. The results can be used to prepare the route control tables (conflicting routes, point positions, and occupancy detection).
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