Heading into 2020, the MBTA does not have a timeline for putting its new Orange Line cars back into service after the trains were pulled from the rails in November.

MBTA spokeswoman Lisa Battiston said Tuesday that tests are ongoing to solve an issue with pads that sit between the train cars and their wheel assemblies.

"Vehicle engineers continue to test a fix with the new cars," Battiston told the News Service in an email. "Following the success of these tests, the MBTA anticipates the new cars being put back into passenger service. The MBTA will provide an update after engineers have completed the process of collecting and analyzing the data generated through testing."

Battiston did not provide a specific estimate of when the vehicles, launched in August, will once again enter operation, and she did not respond to follow-up inquiries seeking a timeline.

The first six-car set began running passenger trips in August following a celebratory press conference. MBTA officials pulled the cars from service in September after a door leaf opened while one of the vehicles was moving, then reintroduced them after a repair.

Noise produced by the train prompted the T to take the vehicles offline again on Nov. 18 and attempt to address the pad interface problem.

The MBTA plans to replace the entire existing Orange Line fleet with a larger set of new cars by December 2022