The Ashmont Branch of the Red Line will be shut down on Saturday to allow track work necessary to remove a speed restriction on that stretch of the subway line, the MBTA announced Wednesday.

The newly announced, one-day service suspension comes as shuttle buses are already replacing service on the Red Line’s Braintree Branch for more than three weeks.

“The service suspension will return to its previous location of the Braintree Branch only on Sunday,” the MBTA said in a statement. 

The transit agency said the service suspension on the Red Line was expanded to include the Ashmont Branch on Saturday in order to allow crews to “take advantage” of the construction equipment in the area. Workers will perform track work during the shutdown that is needed to remove a speed restriction on the Ashmont line, the MBTA said.

A round of inspections will also be performed, according to the MBTA, to capitalize on the outage. 

“The MBTA will also maximize this service outage by performing additional work, including proactive overhead tunnel inspections within the Ashmont Branch’s tunnel areas, seeking out any possible water infiltration or structural repair needs with crews on standby to make repairs as needed,” the MBTA said. 

On Saturday, shuttle buses will run between stations from JFK/UMass to Ashmont, as well as from JFK/UMass to Braintree. Riders are also being encouraged to use the Commuter Rail for fare-free service between Braintree, Quincy Center, JFK/UMass, and South Station. 

Rail service on the Braintree Branch from JFK/UMass to Braintree has been suspended since Sept. 6 for track work, which will continue until Sept. 29. Train service will resume on the Braintree line on Sept. 30.