Not long ago there was an askreddit post about people who had killed others and how it effected them (don't know if you saw that). On of the responses was from a train engineer. It was the one that really got me in the gut. It takes a mile to stop a train, so he had hit something like a dozen people in half as many years. Some of them seemed to be suicides, but a lot were people stuck on the tracks. He said they would look up at him, but there was nothing he could do. So eventually, he stopped looking back and would just look at the floor during the collision.
I didn't see that post. I do recall listening to a radio program some time ago that was talking about train engineers, and they were relating the same. It was awful. I remember one engineer related how he was haunted by an incident with a teenage boy that had his headphones on, and was just walking down the tracks with his back to the train. The engineer thought the kid might have known and was committing suicide, but he could never be sure.