rail

be as thin as a rake (British, American & Australian, mainly American)

to be very thin. He eats like a horse and yet he's as thin as a rake. She's as thin as a rail from all that running.

See also: rake, thin

be back on the rails (British)

to be making progress once more. The minister emerged from three hours of discussions, confident that the talks are now back on the rails.

See also: back

go off the rails (informal)

to start behaving strangely or in a way that is not acceptable to society. He went off the rails in his twenties and started living on the streets. By the law of probabilities if you have five kids, one of them's going to go off the rails.

put something back on the rails (British)

be back on the rails - to be making progress once more. With this new album, he hopes to put his career back on the rails.

See also: back

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go off the rails

to be spoiled by bad management. Things were going off the rails here, and no one was getting any work done. This is a well-intentioned system that has been run off the rails.

Etymology: from the idea of a train leaving the rails (= metal bars) it travels on