You also have to ask at what cost to maintain the backup system and how easy it is to test the Disaster Recovery process. If once in a while, you have a few hours delay (or in this extreme case, a whole day) you might ask if it would be worth it, especially if you could only test it by adding random failures to the main system like Netflix do!
As another poster mentioned, they are many, many independent variables in a railway system. In the old days, people recovered from problems by gut feel and experience was OK although there is usually no "right" answer. The newer systems apply some statistical anlysis and try and make the best decision usually with humans doing the last part.
I'm not sure about "because safety" though since signalling systems protect trains from each other and they only have automation in the sense of first train that arrives gets it route sets, the system cannot make trains crash unless there is a critical bug.
As another poster mentioned, they are many, many independent variables in a railway system. In the old days, people recovered from problems by gut feel and experience was OK although there is usually no "right" answer. The newer systems apply some statistical anlysis and try and make the best decision usually with humans doing the last part.
I'm not sure about "because safety" though since signalling systems protect trains from each other and they only have automation in the sense of first train that arrives gets it route sets, the system cannot make trains crash unless there is a critical bug.