The stop markers for freight when needing to stop before a signal seem very small, the stop marker is placed 5-10 yards from a signal (if that) and you have to stop within 5 yards of it. I am not sure if this is a bug or not but it ruins the game immersion a bit coming to a stop 20 yards fron the signal and having to start crawling again.
I've noticed this too: I think it's called a challenge. In what sense does it ruin immersion for you?