This report introduces the design of the control-command safety systems involved in urban, sub-urban or inter-urban guided transport. It deals with the material aspects only, which means: the design of computer architecture and electronic cards. This report also presents the main methods for safety demonstration. The inherent fail-safety is based on failures hypotheses of the components used. Thus with this concept simple components only can be used which limits the processing capacity of the equipment. The probabilistic fail-safety tolerates a residual risk which is then considered as an objective, and is declined as allowances for each sub-system allowing to use computer systems, provided that they are set on adequate architectures. This report witnesses that inherent fail-safety and probabilistic fail-safety are linked and complementary. It is meant to introduce thoroughly the methods of reasoning used in the decision and checking of safety electronic equipments. Some electronic and technological aspects also are addressed. Several conclusions be taken into account in safety analyses are also developed. (A)
Abstract