Microprocessed Signalling Systems: SafetyAnd Reliability Validation
Antonino Merlo, A. Gerecht, G. Pedroso · WIT transactions on the built environment · 1970
As microprocessor technology is becoming more and more advantageous since its use represents a good cost/benefit ratio compared with conventional technology and due to the prudence in regard to new techniques being applied in railway signalling, it has become necessary to develop means for proper systems validation. Techniques such as reliability and safety evaluations, fault tolerance, majority voting, data protection, duplicated software modules and operation integrity checking have continually been refined to meet rigorous requirements for vital and nonvital applications. CMW Equipamentos S.A. has been developing, several programs of microprocessed signaling equipment applied for transit and railroad systems. Experience regarding equipment validation is being applied to different structures, like: Triple modular Redundancy for Interlocking, Speed Code Generation and Train Detection modules; Dual Checked Redundant and Single Channel Microprocessor combined with diagnostic modules, used for on board Automatic Train Control. Considering required operational and performance characteristics, each architecture is applied where most convenient. Suitable safety and reliability levels are achieved with 1 out of 1, 2 out of 2 or 2 out of 3 architectures. This paper describes the methodology that CMW uses for projects with requirements of safety and highly reliable systems and products. It also Transactions on the Built Environment vol 7, © 1994 WIT Press, www.witpress.com, ISSN 1743-3509