Impossible story line
After a one under all drivers are taken off the trains for counselling which normally lasts at least a month. You're not even allowed to drive the train involved to the nearest depot; they send a spare driver to cover. When they do finally let you back you have an instructor sat in the cab next to you for at least the first two weeks.
So I'm afraid this could never happen in real life but why let reality stand in the way of a story.
Never had a one under myself but have been the spare picking up a train afterwards; messy. By the way, two out of three people survive though not necessarily with all their body parts still attached.
Somehow don't think I'll waste my valuable time watching this one ....