MBTA bus service would increase significantly in key areas under a new plan rolled out Monday, but funding and staffing uncertainty pose obstacles for the effort to reimagine a core pillar of the agency’s operations.

In what MBTA General Manager Steve Poftak pitched as an “exciting inflection point,” officials unveiled a draft new map for the constellation of bus routes in Boston and dozens of surrounding cities and towns. Dorchester and Mattapan routes would see substantial shuffles of bus lines, with route changes offset by better service speed and frequency along major arteries and one new bus route added in Dorchester. 

The proposal would boost bus service across the board by 25 percent over a five-year period, including a 70 percent increase in the amount of MBTA bus travel on weekends, aimed at areas where the existing, somewhat archaic bus routes do not currently meet evolving demands on the system.

About 27 percent of current weekday bus service is “frequent,” defined as a bus running every 15 minutes or sooner, under the current schedule. The new draft plan would push that rate up to 50 percent.

T officials project that their plan would newly give 275,000 more Bay Staters access to bus trips every 15 minutes or less, running all day, seven days a week, adding to the 1.5 million residents who have access to high-frequency transit or bus today.

In Dorchester, this means doubling the number of high frequency connections to six, adding service every 15 minutes for the connections between Harbor Point and Uphams Corner to Copley Square and Back Bay, Columbia Road to Andrew (Red Line) and Forest Hills (Orange Line), and Newmarket Square to Longwood Medical Area and the Seaport. Additional midday, evening, and weekend service is expected to create a 50 percent increase in service for Dorchester, according to the proposal.

Mattapan would see a 25 percent increase in service, with the neighborhood-specific summary highlighting improvements on the Route 14 and 30 buses. The neighborhood would also get new frequent service to Longwood Medical and Kenmore on an extended Route 28 bus.

However, persistent financial pressures and ongoing labor struggles could drive a buzzsaw through the lofty effort. The agency estimates the bus overhaul would cost $90 million more per year once implemented, a figure baked into projections that an operating budget gap of hundreds of millions of dollars will erupt at the T next year and grow in subsequent years. To run the increased service, the MBTA would need to hire more drivers, and officials are already struggling to attract enough employees to run the existing bus schedule.

But Poftak sought Monday to position the MBTA as committed to the vision of an expanded bus network in spite of the pitfalls along the way.
“We think this is an important initiative to put forward. This is the MBTA that we think our riders, our bus riders in particular, are really entitled to,” Poftak said.

“There’s been some public discussion with concerns about service cuts and fare increases, and this is our statement that we intend to expand service,” he said. “We will work on solutions for those out years, but we will work on them with this service level embedded in it.”

Many of the route changes floated Monday aim to provide increased service to communities of color and low-income households more likely to rely on buses, which have maintained more demand than the MBTA’s subway and commuter rail options over the past two-plus years of depressed ridership.

“It was demonstrated throughout the pandemic that we have lots of transit-dependent riders that depend on the bus,” Poftak said. “This represents a step forward for the T in terms of making the service better and providing more service.”

Neighborhood specific summaries for Dorchester and Mattapan highlight one new route – the 20 bus which “replaces and simplifies 26 loop on Washington St, 201/202 loop, and 210 on Neponset Ave and maintains/increases Red Line connections at Fields Corner, Ashmont.”

No entirely new routes are proposed in the Mattapan area, but service improvement highlights include an all-day frequency upgrade to the 31 bus between Mattapan and Forest Hills.

Summaries of the proposed changes broken down by municipality or neighborhood are available online, with dozens of documents reflecting the scale of the project.

Dorchester’s summary includes 61 changes to existing service, including alterations to routes and adjusted service times. Mattapan would see 21 changes to its routes.

The T will gather feedback on its proposal over the course of the summer, then aim to kick off implementation in spring or summer 2023. Virtual meetings, all at 6 p.m., are scheduled regarding the entire system on Thurs., May 19, and focusing on Boston on Thurs., June 2. A virtual public hearing is slated for July 26.

Poftak said he expects it will take five years to gradually transform the bus map.

A State House News Service report contributed to this article.