The train runs on standard gauge tracks, not even close to the Transarctica's wagons. Though I don't know how big were they in the original visual novel Le Transperceneige.
And it only took one giant Avalanche to derail the train


Oh and this happened at some 8848meter high mountain

Some more extra info on the movie's train:



and some actual data:

Movie carrys one clear message, no mather how many people are left in the world there will always be rich and poor...