Edwin_m Posted September 16, 2016 Share Posted September 16, 2016 The computers used for the French CAPI system (which may be in use elsewhere) add a further level of security. They are not simply PCs running a block instrument programme, so no need for apoplexy, but are very heavily modified and dedicated to carrying out very specific functions and they don't do anything else. They probably aren't running fully validated software, with separate processors that have to be in agreement as a precaution against random faults. Both would be considered essential in British practice for any hardware that gets anywhere near authorising trains to enter a single line. Link to post Share on other sites More sharing options...
Pacific231G Posted September 17, 2016 Share Posted September 17, 2016 They probably aren't running fully validated software, with separate processors that have to be in agreement as a precaution against random faults. Both would be considered essential in British practice for any hardware that gets anywhere near authorising trains to enter a single line. Why would you assume that Edwin? I've not been able to find detailed information about the inner workings of the CAPI system beyond its functionality but it's unlikely to have been built to lower standards than any other signalling system and would certainly have had to satisfy a detailed safety case. What does seem to have been different from traditional British practice in much of continental Europe has been the use of different signalling "regimes" depending on the traffic level and whether lines carry passengers or not. It's arguable that the rigid application of rules developed for the safe running of main lines made many lightly trafficked lines in Britain uneconomic where a simpler system would have been completely adequate. Link to post Share on other sites More sharing options...
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