The MBTA is taking the first step in its planned Commuter Rail overhaul by piloting eight new trips a day on the Fairmount Line through the middle of Boston.

The T will add four new trips in each direction for the line that runs from Hyde Park through Mattapan Square and Four Corners into South Station, through minority-heavy areas of the city historically — and currently — underserved by public transportation, officials announced on Monday.

This pilot, originally put forward by Boston Mayor Martin Walsh’s administration, will cost the T $1.1 million a year, and will aim to add 400 new daily riders. The T’s oversight board approved it on Monday.

“I’m pleased that we are able to deliver on improvements to the Fairmount Line that will result in meaningful improvements to service,” T General Manager Steve Poftak said.

Walsh said in a statement, “The Fairmount Line serves the heart of Boston, running through many of our communities with the longest commutes and least access to high frequency transit.”

The T will also test fare machines along the route that allow people with Charlie Cards to use them to pay for trip, and to transfer to buses for free. Normally, riders can’t pay for the Commuter Rail with a Charlie Card.

The T and local officials have worked to build up the Fairmount Line as a way to better serve the many riders along that corridor through the middle of the city, including cutting the price and adding stations.

Still, ridership has lagged, with the line carrying the lowest ridership in the system, with 2,600 people daily on the short line, which is only 30 minutes from end to end on a good day. The T says it would spend an additional $100,000 on advertising for these new services, which include new inbound trips leaving Readville at 5:10 a.m., 9:25 a.m., 3:05 p.m. and 3:53 p.m., and new outbound trips leaving South Station at 7:35 a.m., 9:15 a.m., 6:50 p.m. and midnight.

Many of these rides, officials said, are on “deadhead” trips, so the trains would be passing through anyway.

The T oversight board late last year instructed officials to begin a full transformation of the system, increasing frequency in all directions and moving toward electrification.