Cool video, I was involved in something close to that a number of years ago. 14 inches of rain fell in a day in the area around Union, Missouri. The water would all eventually have to drain to the Missouri River near Washington, MO maybe 10-12 miles away.
This was on the UP's ex Mopac St. Louis-Jefferson City double track.
We had flash flood warnings for the trains. It had stopped raining by the time my train rolled to a stop about 4AM at the west end of town, stopped by two train ahead. Never noticed any rushing water on St. John creek at that time.
Awhile later, the first train in line reported that went into emergency while sitting still. They would find out a mudslide had turned over a few cars.
The track inspector was out about 6AM. He highrailed on west to the rear of my train and told us to pull east as far as we could. He later picked us up and showed us the rear of our train, about six cars from the rear of the last car, water was rushing over the track and a bit farther back the track was hanging in the air. Pretty cool.
Later in the day, while M/W forces were assessing a bridge at mp63, they were just about to OK it for traffic when one of the abutments tilted into the stream.
Water is a great force and has always been a source of track problems.
Dan