There were more delays on the Green Line Wednesday night.
The MBTA said the delays, of about 20 minutes, were impacting the C and D branches due to a track problem at Kenmore.
Shuttle buses were providing alternate service from Kenmore to Fenway and St. Mary's, the agency said.
The MBTA said in an update later Wednesday that the track department was on scene working to resolve the issue.
Further details on the track problem were not immediately provided, and there was no timetable for regular service to resume.
