WORCESTER, MA — Some commuter rail riders are in for a big change starting in February. Weekend trains between Framingham and Back Bay will be replaced by shuttle buses as the MBTA works on a key safety project.

The change starts Feb. 29 and lasts through May. During that time, the MBTA will install positive train control (PCT) systems along the corridor. The work will leave some users without service entirely on weekends — shuttle buses won't stop at the Auburndale, West Newton, Newtonville, Boston Landing, and Landsdowne stations. Trains will run normally between Worcester and Framingham, according to the MBTA. The shuttle buses between Framingham and Back Bay will be free, and you can see a schedule on the MBTA website.

PCT is seen as a key safety feature to prevent trains from derailing or colliding. PCT was absent in recent high-profile Amtrak crashes, like the 2017 derailment in Dupont, Wash., and a 2015 derailment in Philadelphia. "The safety system works through signals and transponders along the rail corridor that transmit data to the train, onboard controls that can regulate a train's speed, and communications throughout the commuter rail network." — MBTA website The MBTA will have spent about $500 million on PCT and other safety upgrades by the end of 2020. The system is in place across much of the commuter rail network, but is still in the testing phase.