Maybe if someone figures out how to slam a train into a skyscraper. This seems rather impractical though, as terrorist attacks go. But that's what it took for

Maybe if someone figures out how to slam a train into a skyscraper. This seems rather impractical though, as terrorist attacks go. But that's what it took for air travel. Hijackings were even relatively common pre-9/11[1], and they didn't even bother to start locking the pilot cabin door (probably one of the only security measure implemented after 9/11 worth anything at all) until someone did something that extreme. [1] https://aviation-safety.net/statistics/period/stats.php https://aviation-safety.net/statistics/period/stats.php