Not quite in order from the movie.
The crossing of the Marquette and Huron Mt. RR about a mile south of Big Bay. May have been LS&I then.
I read in a book about this movie that somewhere down the CNW line there was a state police post that would call and advise the crew when the next train was getting near so they could be ready for the shots involving arrivals. There were 2 in this flick.