RAILWAY SYSTEM ENGINEERING


OUR EXPERTISE


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Fersil presents the expertise of the CLEARSY company, specialized in the development of safety critical systems.

OUR EXPERTISE IN SAFETY CRITICAL SYSTEMS


Located in Aix en Provence, Lyon, Paris and Starsbourg, CLEARSY uses its many skills and formal methods, operational safety and electronics to provide you with a fault-free system and thereby guarantee no errors.  With its broad experience in the railway sector, CLEARSY is known for its ability to adapt to any type of constraint and provide clients with solutions suited to their needs.

In these pages, you will be able to discover our solutions, resources and responses for the railway sector market.

As part of our safety approach, we develop systems and software that are secure and guarantee total user safety.

To this end, we are involved in various disciplines and apply our skills to diverse fields:

> the development of safety systems using formal methods
> operational safety
> the development of systems that comply with railway system standards
> safety software
> electronics

In and of itself, this approach is the vector of secure and innovative systems.

USE OF FORMAL METHODS


The B method is a formal method for the development of systems and software that we use. It allows us to rationalize and model the behavior of a program with B language, then, via successive refinements, to create a concrete model.

IT IS USED IN THE CONTEXT OF:
> the realization of accurate software through construction
> the modeling of systems within their environment
This method is used industrially in the railway system sector.  It is widely distributed and recognized in the world of academia

CLEARSY pursues its development in collaboration with industry, and research centers (by example: Development of SIL4 Safety Software for the Fixed Automatisms of Val de Roissy).

OPERATIONAL SAFETY


Operational Safety (referred to as SDF) is a mandatory step in terms of studying the viability and cohabitation of a system with its environment. It ensures the perfect operations of the system in various situations while preserving the integrity of its environment.

In order to conduct the safety analysis study, CLEARSY follows various steps, including:
> the Preliminary Risk Analysis (PRA)
> the Failure Mode Effects and Criticality Analysis (FMAEC or AMDEC)
> the Software Effects Error Analysis (SEEA)
> the Fault Tree Analysis (FTA)
> the Failure Combination Method
> Others…

CLEARSY consultants have contributed improvements to these well-known methods, referred to as follows:
>
Formal Failure Mode Analysis of Effects and Criticality (FFMAEC)
> Formal Fault Tree Analysis (FFTA)

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Systems that Comply with Railway System Standards

> CLEARSY works on projects of the SIL2, SIL3 et SIL4 type (IEC 61508, EN 50126, 3N 50128, EN 50129 standards) and in close collaboration with renowned users, contractors and industrial partners in the railway system world (ALSTOM, RATP, etc.)

ELECTRONICS

> CLEARSY is currently working on numerous projects involving the integration of electronic components.