"Last of the Giants, Volume 2" had an interview with a guy that hand-fired a Big Boy (light) from where it broke down to the shop. He said in order to make it as "easy" as possible for him, they way overfilled the tender, with a couple of tons of coal ending up in the cab, so all he had to do was pick it up and toss it in the firebox.
In another interview in the same movie, they said a Big Boy got its throttle stuck, and stalled, and by the time they got the mechanical stoker shut down and it ran out of steam, it had ground down through the rails into the ties and ballast.