Boston’s transit agency is slowly returning to normal after a series of crippling snowstorms and frigid temperatures.

The MBTA restored service to most subway/trolley branches Sunday just in time for the Monday morning commute. Service was restored to the Mattapan branch on Monday morning.

All subway/trolley lines are now operational for the first time since Feb. 1.

Support for GBH is provided by:

Buses are running on a regular weekday scheduled, but delays are expected.

Commuter rail trains are running on what the T calls a “modified” schedule Monday and passengers are being told to expect delays and cancellations.

Ferry service is back to normal.

General Manager Beverly Scott, who had estimated it could take a month to restore the system, said the latest restorations are a “major step.”