Formal Verification of Railway Timetables - Using the UPPAAL Model Checker

Abstract

This paper considers the challenge of validating railway timetables and investigates how formal methods can be used for that. The paper presents a re-configurable, formal model which can be configured with a timetable for a railway network, properties of that network, and various timetabling parameters (such as station and line capacities, headways, and minimum running times) constraining the allowed train behaviour. The formal model describes the system behaviour of trains driving according to the given railway timetable. Model checking can then be used to check that driving according to the timetable does not lead to illegal system states. The method has successfully been applied to a real world case study: a time table for 12 trains at Naerumbanen in Denmark. Keywords: formal methods • model checking • UPPAAL • railways • timetables 1 Research in optimisation models and techniques for generating optimal timetables have been done [6], but these are very rarely used by the railway operators.

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“…It should be noted here that a number of studies have addressed the assessment of railway safety properties, while tackling different use cases. In [43] and [44], the reliability of railway interlocking systems is considered, while [45] deals with the analysis of railway timetables. In [46], a moving block signaling system endowed with autonomous driving is modeled and analyzed, while considering various driving strategies.…”

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