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2 Archives of Transport System Telematics

2 2013

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Semi-formal methods in safety railway control systems validation

Magott J., Lewiński A., Perzyński T

Archives of Transport System Telematics

2013

Vol. 6, iss. 1

32--36

Th e paper deals with extending the obligatory methods of safety proof of railway control and management computer systems towards more formalized methods based on mathematical apparatus. Such semi-formal methods are recommended by existing EU standards for the design, but also to demonstrate safe operation in accordance with the principle of the rail fail-safe rule, where no single error does not lead to catastrophic situations. Th e paper proposes an extension method of FTA (Fault Tree Analysis) method to FTTD (Fault Tree with Time Dependencies), and an analysis of THR method (Tolerable Hazard Rate) to the analysis of probability of catastrophic fault based on stationary Markov processes. Basic methods and their extension are shown on typical examples of rail automation systems: cross-level protection system and interlocking system.

Safety transmission in railway application – cryptographic approach

Lewiński A., Łukasik Z., Bester L.

Archives of Transport System Telematics

2013

Vol. 6, iss. 3

18--22

The paper deals with assumptions for an open transmission in railway control applications ensuring the SIL4 safety integrity level. Using the public transmission standards, especially the wireless transmission (including radio access to Internet) requires the appropriate protection to ensure the data integrity (protection against fault and lost of transmission) and encoding (protection against unauthorized access). The estimated this way the THR values, even for single transmission channel does not differ for fault level of computer hardware in redundant structures. The theoretical results are compared with experimental tests of polish railway automation systems.