> Presumably switches already report their position to somewhere.

Yeah and this somewhere already knows whether a crash is going to happen. In which case your solution brings no benefit. You can't rely on the correctness of a system, which you want to make an alternative to, to help in the case the original system fails.

This discussion focuses on a non-problem (granted partly due to an imprecise comment of mine). The system knows where all the trains are and also that a crash will happen, if the decision is made, that then indeed was made.

What is needed is that the system needs to convince the operator there is still a problem, after it proved itself unreliable. My suggestion would be a log of the constraints the prover encountered while determining whether there is a conflict. This certainly already exists somewhere in the background, but I am not aware whether that is currently shown to operators in deployed systems. It does exist somewhat in the research systems we use in university.