[pieceofthepuzzle]

“I read that the Metro-North trains are supposedly equipped with Automatic Train Control.
Maybe the line's maintenance isn't so good? “

I would think that train engineers, at this point in time, should be the second-level of safety and control - not the first. There should be no way that that train should be capable of getting anywhere near that curve at that speed. There should be sensors along the track that monitor speed, and an auto-feedback that adjusts speed if inappropriate for that section of track.

[Paladin2]

"There should be sensors along the track that monitor speed, and an auto-feedback that adjusts speed if inappropriate for that section of track. "

My understanding is that is roughly what ATC is supposed to do.