The MBTA’s Red Line is back in business. A three-and-a-half-week closure of its Braintree Branch ended on schedule Monday with 18 miles of tracks freshly repaired. For the first time since Sept. 5, the subway system can take riders between Braintree and Boston in one smooth ride.

MBTA riders on the Red Line's Braintree branch were greeted with the fastest commutes in years Monday, after a 24-day closure to remove slow zones on the line. It's the first time in at least a decade that there were no Red Line slow zones south of JFK/UMass.

After a Green Line derailment near Lechmere station in Cambridge sent seven people to the hospital Tuesday, the MBTA moved to replace the line with shuttles as federal and state investigations