The MBTA is proposing a new bus map. Here’s what it would look like.

Proposed frequent-service bus routes on the MBTA's new bus network map, released on Monday.MBTA

The Massachusetts Bay Transportation Authority published a map Monday of the new bus service network it plans to roll out over the next five years to increase service and reliability.

MBTA General Manager Steve Poftak said the new bus network would increase overall service by 25 percent and give 275,000 more people access to a bus that comes at least every 15 minutes every day of the week. The map is years in the making and part of the T’s larger goal of improving and electrifying bus service by building new electric bus facilities and bus-only lanes.

The map, available on the MBTA’s website, will undergo a months-long public comment period before it is finalized and implemented starting next year, Poftak said.

“Where people live, … where they work, where they go to school has changed a great deal, and we would like to change with it,” he said. “We’d like to not only become more efficient, in terms of how we get people from place to place, but also figure out where we need to add additional service.”

Today, only 27 percent of the T’s weekday bus service has buses showing up at stops every 15 minutes or less, Poftak said. Under the new network, 50 percent of weekday service would be that frequent. Everett would see a 70 percent increase in overall service, measured in miles traveled, Lynn would see a 40 percent increase in service, and Roxbury would see a 25 percent increase in service. 200,000 more residents would gain access to frequent service to Longwood Medical Area.

The new network would bring all-day frequent service to communities that currently don’t have any: Everett, Lynn, Medford, Somerville, South Boston, and West Roxbury.

This is the first time the MBTA will comprehensively change its bus network map since the 1920s, according to MBTA spokesperson Joe Pesaturo. The agency expects to spend $90 million on the expanded service starting in fiscal year 2028, Pesaturo said via e-mail.

As the MBTA plans for the long-term expansion of bus service, it is still struggling to hire drivers and maintain its current level of service. The T cut overall bus service in December by about 3 percent after regularly having to drop about one in every 20 scheduled trips because of a lack of drivers. COVID-19 absences during the Omicron COVID-19 surge in January forced the T to continue to drop around one in every 20 trips on the reduced schedule.

The number of dropped trips has improved slightly in recent weeks, said Kat Benesh, the T’s chief of operations, strategy, policy and oversight, but the agency is still not delivering all of its scheduled bus service.

“Our goals here are to get to the levels where we can first deliver the service that we currently have scheduled and then add to this service incrementally over time to actually fully realize the potential of bus network redesign,” said Poftak.

During the COVID-19 pandemic, bus ridership has been the most resilient among the different modes of T transit. As of the week of April 25, weekday ridership was 66 percent what it was in the last week of February 2020, according to MassDOT data. Subway ridership is around 50 percent of what it was pre-pandemic.

A 28 bus on Blue Hill Avenue in Boston.Lane Turner/Globe Staff

The bus with the highest ridership is the 28 bus, according to state data, which has been free to ride since Boston began reimbursing the T for fare revenue last August. In March, Mayor Michelle Wu began a two-year pilot program to eliminate fares on the 23 and 29 buses as well using money provided by Boston from its federal COVID-19 relief fund to reimburse the T.

The MBTA will hold a series of virtual and in-person public meetings about the proposed map starting this week throughout the summer.