Software design criteria for the safety-critical protection of automated transit systems

As the microcomputer replaced discrete logic in safety-critical applications, it became necessary to reexamine the methodologies used to analyze, design, and test such products. From the new methodologies established, fifteen software design rules have been created to ensure the safety of automated transit systems. It is shown that the fifteen software design rules along with a top-down structured and systematic design approach provide the software engineer with the tools and techniques to ensure against: (1) an omission or misapprehension of a safety-related requirement: (2) mistakes in the interpretation or the coding of a safety-related task: and (3) miscommunication or imperfect definition of the design objectives among those responsible for the certification of a design