Fitchburg commuter rail line to bus passengers between Boston and Littleton Updated Feb 09, 2021; By Michael P. Norton | State House News Service For two months, beginning on March 1, users of the Fitchburg commuter rail line will need to use replacement bus service over a long stretch of the line, a switch that will add to travel times. The MBTA on Monday announced its plans, which will affect service from the Littleton/Rte. 495 station through stops in Acton, Concord, Lincoln, Waltham and Belmont, with bus service delivering passengers to Alewife Station on the Red Line. The T says the diversion is needed to install anti-collision train technology, federally mandated work that the agency says will be completed over six months instead of a projected 12-month timeline if executed with a weekends-only schedule.