jump the rails

Related to jump the rails: off the rails

jump the rails

1. Literally, of a train, to derail from the track and lose control. Due to a technical issue, the train wasn't able to slow down ahead of the turn and ended up jumping the rails because of its speed.
2. By extension, to veer off in very unexpected directions; to lose or change focus in surprising or bizarre ways. The long-running drama has by this point jumped the rails so completely that it would be foolish to try and summarize it for the uninitiated. The manager's speech really jumped the rails about halfway through, shifting into a weird commentary on the nature of corporate America.
See also: jump, rail
Farlex Dictionary of Idioms.

jump the rails

AMERICAN
If something jumps the rails it suddenly changes completely so that it seems to be something different. The story doesn't follow the traditional fairy-tale pattern but jumps the rails halfway through.
See also: jump, rail
Collins COBUILD Idioms Dictionary, 3rd ed.

jump the rails (or track)

(of a train) become dislodged from the track; be derailed.
See also: jump, rail
Farlex Partner Idioms Dictionary
See also:
  • jump the track
  • jump the track(s)
  • chug
  • chug along
  • aboard
  • all aboard
  • on board
  • train
  • excess baggage
  • book (one) on (something)