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Methodology for Assessing Safety Systems
Application for a Railway Hot Box Protection
System
Joffrey Clarhaut, Etienne Lemaire, and El Miloudi El Koursi
Université Lille - Nord de France,
Institut National de Recherche sur les Transports et leur Sécurité, INRETS,
BP317, 20 rue Elisée Reclus,
59666 Villeneuve d'Ascq Cedex, France
{joffrey.clarhaut, etienne.lemaire,
el-miloudi.el-koursi}@inrets.fr
http://www.inrets.fr
Abstract. This paper presents a methodology for assessing railway
safety systems. This methodology is based on a SADT model of the
system and on a probabilistic evaluation of each function and sub-
function of this model. As an illustration, this methodology is applied
to assess a specific railway protection system: the hot axle box pro-
tection system. Risks involved with a hot axle box are also presented.
Finally, results obtained in the case of a high-speed rail line are anal-
ysed.
Keywords: SADT Modelling, Probabilistic evaluation, Hot Box Protection
System, Railway
1
Introduction
In railway systems, safety and reliability levels of a number of existing systems
are based on knowledge and existing rules of a single railway company. These
rules and this knowledge may not be modelled or demonstrated. Moreover,
these proprietary rules can not be used in order to define new specifications
for equipment admittance. Several problems arise: how to establish safety
and reliability levels when the system can not be treated using the concepts
of the EN50126 standard [1]? How to check these levels and to prove that
they meet the regulatory requirements of the infrastructure manager?
In this paper, we define a general method for the determination and the
demonstration of safety levels. This method consists of two steps: a first step
of system modeling and a second step of evaluation of the various sub-systems
of the considered system.
The present research work has been supported by the French Railway Safety
Authority (EPSF). The authors gratefully acknowledge the support of this insti-
tution and reviewer's comments.
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