The taxpayers weren’t the only ones getting screwed.

A Metro-North worker resigned last month after the MTA’s watchdog caught him having sex with a woman at a railyard — while collecting overtime pay, according to a new report.

Investigators from the office of MTA Inspector General Carolyn Pokorny observed the machinist, a 25-year veteran, bring an unauthorized woman onto the grounds of the Croton-Harmon property three times last spring — including at least one time that got steamy, according to the report, set to be publicized later Monday.

On May 16, OIG gumshoes observed the man and woman — neither of whom is identified by name in the report — “kiss and have intimate contact” in a railroad storage yard “behind the open door” of the woman’s Nissan Pathfinder, according to the document.

The trainyard tryst — which went down a mere 10 to 15 feet from tracks “clearly” labeled “No Entry Except Authorized Vehicles,” according to the report — occurred in the middle of the man’s overtime shift and lasted an impressive 77 minutes, GPS data from the machinist’s MTA-issued truck shows.

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