The MBTA suspended Red Line service between JFK and North Quincy Thursday afternoon between 5:25 p.m. Service resumed with "severe residual delays" around 6:20 p.m.
The T was running shuttle buses between Ashmont and North Quincy. From there, service was continuing to Braintree, according to an MBTA alert.
The T had earlier reported a "track problem" between Braintree and JFK stations.
It was part of the same stretch the MBTA planned to close this weekend for winter resiliency work. Saturday and Sunday, service was scheduled to be suspended between JFK and Quincy Center stations, with buses replacing trains on all stops in between.