You've "invented" interlocking railway semaphores, after which the computer science concept was named.
replyCongratulation you are reinventing 1890 state of the art.
replyThe problem is when the modern computer-dependent system replaces the ancient one, and so then the computer is down there is nothing at all.
replyActually in this case it seemed that the opposite was the case, there was another fallback system, but you needed to disregard it, and operate manually, but the operators likely didn't notice that. https://news.ycombinator.com/item?id=50298796
replyWhich is why you generally don't do that.
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