That has to do with FRA rules. In short, mainline passenger railcars are held to a certain standard of crash-worthiness with freight trains. An excessive standa

That has to do with FRA rules. In short, mainline passenger railcars are held to a certain standard of crash-worthiness with freight trains. An excessive standard many will say but none the less its a rule. Subways and metro trains, provided they don't share track with the national network, aren't held to that standard. That's why your BART car is shipped on a flatbed and not under its own wheels.