BOSTON (AP) — The Massachusetts Bay Transportation Authority is fast-tracking work on the Green Line’s D branch in June that will require a full closure of the track for a total of 18 days, officials said.

The MBTA’s Green Line D Track and Signal Replacement Project includes replacing 25,000 feet of track and 6.5 miles of signals — some elements of which date to the 1950s — from Riverside to Beaconsfield stations, the T said.

Beginning after the end of normal service on Friday, crews will work 24 hours a day for a total of 18 days to perform the work.

Starting June 12, through June 20, train service will be replaced with shuttle buses between Riverside and Kenmore, the MBTA said. Shuttles will also be used from June 24 through July 2.

MBTA General Manager Steve Poftak said the work will make the service safer and more reliable.