You can’t see the train cars destroyed and the trains/convoys don’t follow the 90 degree turns.
Find a nice long section of track and park your favorite GV and open up when the train comes along. You’ll get Train destroyed messages but all the cars will keep right on going. It's hard to know which cars are left when they all stay visible.
When the train comes to a corner, it will usually do a series of triangular loops taking quite a bit of time. The truck convoys do this to. You can see an example with the train on the Mindanao map, in sector 6,10, southwest of the radar factory.