So here's the story. Within the first 10 minutes of the picture, the train's engineer learns that he has no brakes AND they're going downhill through the mountains. Now you'd THINK this would mean the movie would be at most 15-20 minutes long...yet somehow they pad it out to full length for a made for TV film! So what do they do? Pad, pad and pad!
You have to understand the context for this picture. The 1970s were HUGE for disaster pictures and this is one of about 19,000,000 such films that were made about impending doom during that time. Earthquakes, floods, fires, boats, airplanes, you name it...and so why NOT make a film about a train full of passengers waiting to die?! Well, common sense would indicate they shouldn't but it was the rage at the time.
Ways they padded some films was make a few characters with some silly backstory...and the one they invested the most energy on was the divorcing couple who hate each other and you KNOW what is going to happen with them by the end of the movie!! Overall, a dumb premise and a film I can't see watching unless you are some sort of disaster movie groupie.