A PUBG Twitch Streamer created a valuable test about what would happen if a train ran into dozens of BRDMs. While the results may shock you, it does stay inside the realm of PUBG. Meaning, the physics work only so far before the systems fail.
Clearly, someone at PUBG Corp didn't want the train to be able to be flipped.
Twitch streamer Wackyjacky101 had the brilliant idea of putting BRDMs, PUBG Loot Crates, and even other vehicles, but nothing could stop the might of the train. This style of train is very common on these types of maps and games, and even in Grand Theft Auto, you can't stop or derail the train. It's an unmovable monster which will destroy anything in its path. It's caused many different YouTube and Twitch content creators to make videos when they spend the entire time trying to derail the train.
They won't ever be able to do it, but that doesn't stop them from trying.