More than a dozen MTA bus and train operators were busted driving for-hire vehicles like Ubers and Lyfts during mandated rest time between shifts, according to a series of 2018 investigations published by the agency’s Inspector General on Wednesday.

The IG’s office says it used Taxi and Limousine Commission data to catch 16 bus drivers and four train operators driving for-hire cars during their regulation eight hours of down time in the 16 hours preceding their transit shifts.

One moonlighting bus operator never once received the required eight hours in a stretch of three shifts in January 2018 — and sometimes had as little as two-and-a half hours rest, the IG found.

MTA workers can get approval for second jobs, but the agency told the IG that drivers would never be OKed for outside gigs operating a motor vehicle for safety reasons.

Fifteen other operators were also busted just for driving for-hire vehicles without authorization.

One such train operator was found to have driven 337 for-hire vehicle trips over an eight-month period. He received a 30-day suspension without pay for the transgression.

Of the drivers caught driving instead of resting, three were fired, one retired, two resigned and the rest were suspended without pay for a period, the IG said.

The investigator recommended the agency immediately reiterate the rules to all operators with TLC licenses, and transit officials complied.