Aye as the sibling comment says it's not guaranteed to happen, I'm considering the worst case scenario outside of collision (needing to move trains that can no longer move themselves, needing to offload and transport stranded passengers, causing further delay, etc)

For what it's worth overconfident guy kicked off an interesting conversation!

It's also quite possible that I'm overcautious and the future will have trains within braking distance of each other and it turns out to be no big deal.

Thoroughly enjoyed thinking about the scenario in any case. Some proper Hacker News brain tickling in this thread :)