CLEARSY specializes in designing safety critical systems. From design to commissioning, we develop SIL1 to SIL4 certified systems. Our expertise includes data validation, system verification and safety demonstration. Also we promote the formal B method that has the potential to disrupt safety critical system development. CLEARSY proposes solutions to increase passenger flow and safety of the busiest commuter lines, improve train operation safety, reduce costs incurred by safety system development and verify safety critical systems CLEARSY is now passing a new milestone, thanks to the acquisition on July 2018, of the company ERSA, known by its competencies in the main lines. it has used its software architecture, development and design skills to translate the complex detail of European Interoperability’s ERTMS / ETCS / EVC specifications into a suite of tools which are supplied now by CLEARSY.