Two rtk receivers with LTE including a little battery backup would cost what, $2,000 per car tops?

Presumably switches already report their position to somewhere.

It's absolutely unacceptable for this problem exist in today's world.

> 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.

Multiple independent systems. Easy to ignore a single system, but two or more ? Would have to have a death wish

When I wrote that comment I would have answered, that you already need to distrust a system, that of course still have the authority to sound like it would be right. Also from other accident reports, my understanding is that relying on yet another system causes people to make even more errors, while when they start to manually assess the situation from first principles, they are able to grasp the fundamental error, because they are questioning every assumption, as they are reconstructing a world model different from the automatic system. But the latter takes more time and effort, so people tend to do the former.

The thing is that in modern automated dispatching you only have the same world model as the automatic system, so when there is an error you have the same world model as the system, but that just detected, that that does not equal the actual state of the world. And often the error is in fact a false positive.

But now, I actually think that this accident was caused by several systems being in effect: https://news.ycombinator.com/item?id=50298796