Service on the Mattapan Hi-Speed trolley line was restored Tuesday afternoon following a series of vehicle malfunctions that brought the railway to a halt on the morning of New Year’s Day. The trouble began on Monday just before 7 a.m., when one of the 1940s-era Presidential Conference Cars (PCC) broke down at Butler Street station.

“Two trolleys were sent to assist the first disabled trolley, but were unable to push the train to the yard to be fixed,” said a spokesperson for the MBTA. “These two also subsequently became disabled.”

The three disabled trolleys were eventually moved to the car house in Mattapan Square to be investigated and repaired.

“While these trolleys are unavailable, shuttle buses are currently replacing Mattapan Line service,” the spokesperson said. “Maintenance crews are working to repair the trolleys as safely and quickly as possible. The MBTA apologizes for this unanticipated change in Mattapan Line service.”

They remained offline as of Tuesday at 11 a.m. The T announced that service had been restored around 2 p.m. on Tuesday.

The T has plans to phase out the orange-colored trolleys, which have been rebuilt a few times since they were introduced into service after World War II. They would be replaced with eight “Type 9” vehicles currently running on the Green Line, which can carry more passengers.

The newer vehicles must be refurbished before putting them on Ashmont-Mattapan loop, which must also see upgrades to support the different type of vehicles.

On weekdays at this time, the trolley line transports an average of 3,823 people, down from a pre-pandemic number of 6,580.