City officials will launch a massive planning initiative next week that will center on the nine-mile commuter rail line between South Station and Readville that stretches through Dorchester and Mattapan. Mayor Thomas Menino is hosting a formal kick-off for the planning process at the Strand Theatre next Tuesday at 2 p.m.

The initiative, one of the largest since the city’s planning around the Orange Line in the 1980s, will include an advisory group of residents, community groups, nonprofits, and business owners whose interests span the corridor along the Fairmount Indigo Line. The Boston Redevelopment Authority, the city’s planning agency, is requesting nominations for the group, which is expected to include 20 to 30 members appointed by Menino. Smaller groups are also expected to focus on economic growth in specific neighborhoods along the line.

City officials and neighborhood groups hope the Fairmount Line, with the four new stops the MBTA is now building at a cost of $139 million, will jump-start economic development in the corridor, help rebrand and market the area, and significantly cut down commuting time into downtown, the burgeoning Innovation District, and the Longwood medical areas.

“It’s a comprehensive planning effort coming up with a strategic growth strategy for the Fairmount Line,” said Jeremy Rosenberger, one of the BRA’s project managers overseeing the effort. The effort will include identifying existing or vacant buildings for redevelopment.

According to estimates in a recent presentation from the BRA and the Boston Foundation, 160,000 people live within a half-mile radius of the line as it runs between South Station and Readville, many of them low-income and without a car.

The trains now stop at Uphams Corner, Morton Street, Fairmount, and Readville, leaving most of the corridor without access to the rapid transit. The new stops, which are expected to be completed in the next two years, include Four Corners, Talbot Avenue, Newmarket, and Cummins Highway/Blue Hill Avenue. The Four Corners station is expected to be completed this December; the Talbot station next January; and Newmarket next February. Construction at the proposed Blue Hill Avenue/Cummins Highway stop, which has been put on hold by neighborhood complaints over its siting, will start this fall. Several existing stations and bridges on the route have already been rehabilitated to the tune of $37 million.

Community development corporations have bought up land around the line – enough to control 800 units of housing and 200,000 square feet of commercial space. The Dorchester Bay Economic Development Corporation picked up two Pearl Street sites that once were home to factories for development of hundreds of units of affordable housing and new businesses, including a job training center.

“We want to build upon what they’ve done,” Rosenberger said. “That allows the city to really get into the details about how we can bring economic development to this corridor.”

Jeanne Dubois, the head of the DBEDC, said fear of gentrification – a situation in which low-income residents are forced to leave because of rising rents – was a driver of her community development corporation’s efforts. “We were worried with the new stations coming, people would be pushed out,” she said.

State Rep. Russell Holmes, who represents Dorchester and Mattapan, said concerns over gentrification have frequently surfaced at community meetings. “We really want the community to become more diverse and encourage folks to stay,” he said. Holmes added that he was somewhat hesitant about the planning initiative, based on the dispute over the Blue Hill Avenue/Cummins station that remains unresolved. MBTA officials have said they are planning to move ahead with the siting they have identified.

Another looming issue, as city and neighborhood officials push transit-oriented development, is the MBTA’s proposals to cut back on service and hike fares in the face of its heavy debt load.

Both Holmes and fellow state Rep. Linda Dorcena Forry raised the possibility of the Legislature easing the MBTA’s debt load by dipping into the state’s “rainy day” fund, which is often used to plug gaps in budget holes.

The Fairmount Indigo planning effort is expected to start this spring and last two years. The BRA has released requests for proposals for consultants to work with the corridor advisory group on the planning.

“There’s so much land and so much opportunity,” said Rep. Forry, who added that she hopes the effort will incorporate past plans, such as the BRA-led Mattapan Economic Development Initiative, which focused on improving the neighborhood’s commercial districts and creating a retail brand.

In a statement, Menino said the planning study will bolster the city’s efforts to “invigorate” the community. “Mass transit is an important catalyst for economic growth and by investing in these great neighborhoods, we can fuel economic development and work to improve access to transit, housing, and jobs.”

More information is available at a website set up by the BRA: fairmountindigoplanning.org.