22 (MBTA bus)

Massachusetts Bay Transportation Authority Primary Bus Corridors

Company type	Public transit service designation
Industry	Public transportation
Founded	2004
Headquarters	Boston , United States
Area served	Boston metropolitan area
Products	Bus rapid transit and high-frequency bus routes

Primary bus corridors of the Massachusetts Bay Transportation Authority (MBTA) consisted of 15 routes characterized by elevated ridership and frequency standards established in the 2004 MBTA Service Policy. Collectively, these routes represented roughly 40% of the MBTA's entire bus passenger volume. Serving Boston’s most densely populated neighborhoods, they offered frequent service and seamless connections to other MBTA modes, thereby facilitating extensive regional accessibility.</ref>

As integral components of the MBTA’s core transit network, these primary bus corridors were prominently displayed on updated system maps alongside rapid transit and commuter rail lines. They received prioritized attention for enhancements such as late-night service trials and have played a significant role in urban planning and transit engineering research. The MBTA’s 2024 Bus Network Redesign is moving away from the "key bus route" designation, adopting instead a more inclusive high-frequency network concept.

History

In November 2006, the MBTA initiated a program aimed at improving service quality along its primary bus corridors. The 2008 Service Plan advocated for further enhancements, including the elevation of Route 31 to key corridor status.</ref> Subsequently, a $10 million Key Routes Improvement Project was launched, funded in part by the American Recovery and Reinvestment Act of 2009.</ref> While initially encompassing Silver Line operations, these were later separated into an independent initiative. The project wrapped up in 2013, although some planned improvements remained incomplete.</ref> By mid-2017, these key corridors exhibited superior reliability compared to other routes, with on-time adherence rates of 75% versus 61%.</ref>

Research conducted in 2012 demonstrated that residing near key bus corridors was associated with decreased taxicab usage, a trend not observed with other bus lines, underscoring their competitive advantage within the transit market.</ref>

In April 2014, extended late-night operations on key corridors commenced as a one-year pilot program, contingent upon ridership levels and sponsorship support.</ref> However, by April 2015, late-night service hours were curtailed and five key corridors lost their extended schedules, with all late-night extensions fully discontinued by March 2016.</ref>

These primary bus corridors were integral to Boston Mayor Marty Walsh’s "Go Boston 2030" initiative, which set a goal for all residents to be within a ten-minute walk of either a T station or a key corridor stop.</ref> Additionally, a new key corridor was proposed to connect the Longwood Medical Area with JFK/UMass station via Roxbury.</ref>

In May 2022, the MBTA unveiled a draft redesign of the bus network proposing modifications to most key corridors while upgrading several additional routes to high-frequency service levels complementing rapid transit lines.</ref> An updated version of this plan was released in November 2022.</ref>

Criteria for Key Corridors

According to the MBTA’s Service Delivery Policy, Key Bus Routes are designated based on five main factors:

• Elevated passenger demand
• Integration within the transit system
• Extensive geographic reach
• Support for significant new developments
• Functioning as bus rapid transit corridors

Policy standards

Primary routes are required to adhere to more stringent service criteria compared to local routes, particularly regarding operational hours and service frequency. The following tables illustrate these distinctions:

Route Category	Minimum service span
Local	Weekdays	7:00 AM – 6:30 PM
	Saturdays	8:00 AM – 6:30 PM
	Sundays	10:00 AM – 6:30 PM
Key	Weekdays	6:00 AM – Midnight
	Saturdays	6:00 AM – Midnight
	Sundays	7:00 AM – Midnight

Route Category	Minimum service frequency
Local	Peak periods (AM & PM)	Every 30 minutes
	Off-peak periods	Every 60 minutes
	Weekends	Every 60 minutes
Key	Peak periods (AM & PM)	Every 10 minutes
	Midday hours	Every 15 minutes
	Evenings and weekends	Every 20 minutes

Route list

Within the MBTA network, there are 15 designated key routes: 1, 15, 22, 23, 28, 32, 39, 57, 66, 71, 73, 77, 111, 116, and 117. These routes have been the focus of numerous requests from both officials and the public for the introduction of limited-stop or express services aimed at improving operational efficiency and addressing rider demand.

1

The 1 Harvard Square–Nubian Station line connects Cambridge with Roxbury and originated in September 1962 through the consolidation of two routes that previously terminated at Massachusetts Avenue (currently Hynes Convention Center). In May 1987, the route was shifted from Washington Street southeastward onto Albany Street and Melnea Cass Boulevard to provide access to Boston Medical Center. Its primary corridor follows Massachusetts Avenue, starting from Harvard, passing the Massachusetts Institute of Technology, crossing the Charles River via the Harvard Bridge into Boston. It continues beyond the Berklee College of Music to Boston Medical Center before heading southwest toward Nubian station along Albany Street and Melnea Cass Boulevard.

In a plan from 2015, Cambridge proposed implementing transit signal priority for route 1 at selected intersections to enhance bus movement. The network proposals released in 2022 did not suggest any modifications to this route.

Transit advocacy organization Transitmatters identified the number 1 bus as both the slowest and most prone to bunching within the MBTA system as of October 2023. It recorded an average velocity of just 6.55 mph and experienced a bunching rate of 17.7%, highlighting notable challenges in maintaining consistent and reliable service.

15

The 15 Fields Corner Station or St. Peter's Square–Ruggles Station route travels from St. Peter's Square in northern Dorchester northward along Bowdoin Street, then west on Hancock Street and north on Columbia Street reaching Uphams Corner. From there it proceeds west along Dudley Street to Nubian station, continues west on Malcolm X Boulevard, and then moves north on Tremont Street to reach Ruggles station. During nighttime hours and weekends, service terminates at Fields Corner station, operating via Geneva Avenue and Bowdoin Street back to St. Peter's Square.

This route began bus operations on April 6, 1962, replacing previous trackless trolley service between Kane Square and Dudley via Uphams Corner and Dudley Street. Following the Orange Line’s relocation to the Southwest Corridor in May 1987, the route was extended to Ruggles. On August 25, 2024, service was slightly lengthened from Kane Square to St. Peter's Square.

The draft network plan issued in May 2022 suggested extending this route westward to Oak Square, effectively replacing route , thereby establishing an Oak Square–Fields Corner connection. However, the November 2022 revision restored the route’s terminus at Ruggles while maintaining route 65 as a separate line.

22

The 22 Ashmont Station–Ruggles Station via Talbot Avenue operates from Ashmont heading northwest to the former location of Egleston station, then continues northward along Columbus Avenue and Tremont Street, running parallel to the Orange Line before terminating at Ruggles.

On April 6, 1962, buses replaced the previous trackless trolley service, running as the 22 Ashmont–Dudley via Talbot and Warren. Unlike its current routing, it originally proceeded north on Warren Street to . In May 1987, the route was extended to reach Ruggles following the Orange Line Southwest Corridor realignment. Both the May and November 2022 transit network proposals suggested shifting the inner terminal to Longwood Medical Area.

23

The 23 Ashmont Station–Ruggles Station via Washington Street shares its start and end points with route 22 but follows an alternate course. From Ashmont, it travels along Talbot Avenue, then heads north on Washington Street, continuing onto Warren Street until reaching Nubian station. From Nubian, it moves westward along Malcolm X Boulevard to Roxbury Crossing, then proceeds north on Tremont Street to arrive at Ruggles station.

Trackless trolleys were replaced by buses on April 7, 1962, for the route then known as 22 Ashmont–Dudley via Washington Street and Warren. The extension to Ruggles coincided with the Orange Line Southwest Corridor relocation in May 1987.

A study conducted in 2017 identified overcrowding challenges on routes 23 and 28 that could be mitigated by lengthening route 29 and increasing its service frequency. Starting March 1, 2022, a city-sponsored initiative provides fare-free travel on routes 23, 28, and 29 through February 28, 2026. Neither the May nor November 2022 network plans proposed changes to this route.

28

The 28 Mattapan Station–Ruggles Station line connects the neighborhoods of Grove Hall and Mattapan via Blue Hill Avenue, a major arterial road. Historically significant as a busy trunk corridor, in 1945 route 29 Mattapan–Egleston operated with headways as short as 1.5 minutes during morning peak periods. Originally served by streetcars operating on a dedicated right-of-way until bus replacement in 1955, route 28 was introduced in May 1987 to complement route 29. By December 1989, route 28 became the primary service along Blue Hill Avenue while route 29 was limited to peak hours and shorter trips. Some stops received shelters starting in 2001. Between December 2006 and June 2010, morning peak short-turn service ran as route 25 between Franklin Park and Dudley (later Ruggles).

The 2003 Program for Mass Transportation (PMT) evaluated several potential expansions of the Silver Line, including a bus rapid transit (BRT) express overlay for route 28—an idea briefly revived in Silver Line Phase III plans in 2006. In 2009, state officials proposed the 28X, a limited-stop BRT service on one of New England’s busiest bus corridors featuring dedicated lanes on Blue Hill Avenue and queue jump lanes on Warren Avenue. The $114 million project aimed to start construction in April 2010 with service beginning by early 2012.

However, strong opposition emerged due to insufficient community engagement, concerns over loss of parking spaces, removal of median strips, and disruptions caused by extended construction periods. Consequently, the plan was withdrawn by late 2009. In June 2010, MBTA introduced articulated sixty-foot buses on route 28 to boost capacity despite local objections related to stop eliminations in Grove Hall. The Roxbury–Dorchester–Mattapan Transit Needs Study completed in 2012 recommended implementing the express bus concept of the former 28X without building new infrastructure.

In August 2020, MBTA and Boston jointly applied for $15 million in federal funds toward a $30 million Blue Hill Avenue improvement project featuring center-running bus lanes targeted for completion by late 2021; this request was denied in September. A subsequent $25 million federal funding application was submitted in July 2021. A city-funded pilot program provided fare-free rides and all-door boarding on route 28 from August 2021 through February 2022 to enhance travel times along this heavily utilized corridor. Following this pilot’s success, fare-free service on routes 23, 28, and 29 was extended from March 2022 until February 2026. Additionally, in November 2021 Boston secured a $15 million federal grant toward a $39.5 million Blue Hill Avenue reconstruction project.

The May and November network plans of 2022 proposed extending route 28 from Roxbury Crossing through Longwood Medical Area while eliminating the segment between Roxbury Crossing and Ruggles. In February 2024, Boston announced a $44 million Blue Hill Avenue reconstruction initiative incorporating center-running bus lanes with construction expected to commence in 2026.

32

The 32 Wolcott or Cleary Square–Forest Hills Station line operates along Hyde Park Avenue, connecting Forest Hills to Readville and serving the neighborhoods of Jamaica Plain, Roslindale, and Hyde Park. This route runs adjacent to the commuter rail tracks throughout its entire path.

Prior to 1953, Route 32 functioned as a full trolley service between Forest Hills and Cleary Square before transitioning to trackless trolley operation. By 1958, diesel buses had replaced trackless trolleys on the segment south of Forest Hills. A turnaround loop for the trolleys was situated at the intersection of Hyde Park Avenue and Pine Street.

In 1981, Route 31, which ran between Mattapan Square and Wolcott Square, was combined with Route 32 at Cleary Square, forming the Route 32 Forest Hills–Wolcott Square. Meanwhile, Route 50 was adjusted to serve Malone Elderly Housing via River Street and Gordon Avenue. The May and November 2022 network proposals did not include modifications to Route 32.

39

The 39 Forest Hills Station–Back Bay Station route was introduced in December 1985 to replace Green Line E branch service from Heath Street to Arborway, initially intended as a temporary arrangement until 2011. It parallels the Green Line corridor from Heath Street to Copley and provides transfers to both the Orange Line and commuter rail at each terminus, including Amtrak connections at Back Bay.

Route 39 was a pioneer in employing articulated buses regularly within the MBTA system, a practice later adopted by other routes such as the 28 in late 2005. By 2013, it ranked as Boston’s second busiest bus route. The substantial ridership contributed to the expansion of Forest Hills station during the Casey Arborway reconstruction.

The draft network plan released in May 2022 suggested extending Route 39 through and , substituting parts of routes , , and , while eliminating service between Longwood Avenue and Back Bay. However, the November 2022 plan restored Route 39 to its existing alignment and proposed increasing frequency on Route 47 with an extension to Union Square.

57

The 57 Watertown Yard–Kenmore Station line serves the communities of Boston, Newton, and Watertown. It succeeded the Green Line A branch after its discontinuation in 1969. Historically, Route 57 operated limited-stop service within Boston—specifically no passenger pickups along Commonwealth Avenue between Packard's Corner and Kenmore—a practice that ended in December 2006. No alterations were proposed for this route in either the May or November 2022 network plans.

66

The 66 Harvard Square–Nubian Station via Allston route, once operated as a trolley line, starts at Nubian Square in Roxbury and crosses the Southwest Corridor Park near Roxbury Crossing. It briefly shares segments with Route 39 and the Green Line E branch from Brigham Circle up to Boston’s city boundary. Traveling along Harvard Street, it serves Brookline and Allston neighborhoods before diverting to Union Square (Allston), then continues via Cambridge Street and North Harvard Street to its terminus at Harvard Square in Cambridge. This route provides connections with multiple transit lines including the Silver Line, Orange Line, various Green Line branches (B, C, D, E), and Red Line. The May and November 2022 plans did not propose any changes. In August 2024, northbound buses were rerouted through the Harvard Bus Tunnel.

71

The 71 Watertown Square–Harvard station line originates at the lower level of the Harvard bus tunnel, proceeds south along Mount Auburn Street, and continues westward to Watertown Square located in Watertown. At Harvard, buses complete their turnaround by traveling via Massachusetts Avenue, Garden Street, and Waterhouse Street before re-entering the tunnel. The Watertown terminus includes a dedicated right-of-way loop designed for bus turnarounds and passenger boarding.

Streetcar operations on route 71 ceased on September 4, 1958, subsequently replaced by trackless trolleys until March 13, 2022. In 2017, routes 71 and 73 were chosen to participate in a bus rapid transit pilot initiative. Alongside other routes, the 71 and 73 were among the final trolleybus services operated by the MBTA before transitioning to diesel buses in 2022. Although no modifications to the route were included in the 2022 network proposals, Watertown has plans to extend route 71 slightly to Watertown Yard as part of a redesign of Watertown Square.

73

The 73 Waverley Square–Harvard Station route begins at the Harvard bus tunnel and shares Mount Auburn Street with route 71 as it passes through Cambridge and Watertown. It then follows Belmont Street along the boundary between Belmont and Watertown before continuing along Trapelo Road in Belmont, terminating at Waverley Square with a loop at the Waverley commuter rail station on the Fitchburg Line.

Initially operated by streetcars until the 1950s, trackless trolley service was introduced partially in 1957 and fully replaced streetcars by 1958. This trolleybus service continued until March 13, 2022. Recent network plans have not proposed any alterations to this route.

77

The 77 Arlington Heights–Harvard Station line provides a connection between Arlington and Harvard station along Massachusetts Avenue. Prior to the Red Line Northwest Extension in the 1980s, routes 77 and 77A served as the main transit options northwest of Harvard, with combined streetcar frequencies under one minute during peak periods in 1945. Route 77 transitioned to diesel buses in 1955; meanwhile, route 77A converted to trolleybus operation in 1958 to free up streetcars for conversion of the Green Line D branch and to eliminate boarding islands to facilitate better automobile traffic flow. Route 77A offered local service south of the carhouse while route 77 operated limited-stop service; from 1998 until 2005, route 77 largely supplanted route 77A service, which was completely discontinued in 2022. In 2017, Arlington pursued private funding for implementing signal priority, queue jump lanes, and potential bus lanes along its portion of the route. The May and November 2022 network plans did not suggest any changes for this line.

111

The 111 Woodlawn–Haymarket Station route connects downtown Boston with Chelsea via the Bill Russell and Tobin Bridges. Originally run as streetcars between Chelsea Square and Woodlawn under Boston Elevated Railway management starting in 1936, it was replaced later that year by a bus extension of the City Square–Chelsea Square route. The line was extended to Haymarket in April 1975 following closure of the Charlestown Elevated; an extension beyond Woodlawn was partially implemented in January 2001. Service beyond Woodlawn ended in September 2019; Cary Square short-turn trips were substituted with Woodlawn trips starting December 2021.

Route 111 ranks among the MBTA’s highest-frequency numbered lines, operating every five minutes during peak hours. No adjustments were included for this route in either the May or November 2022 network proposals.

116/117

The 116 Wonderland Station–Maverick Station via Revere Street and 117 Wonderland Station–Maverick Station via Beach Street routes provided service to East Boston, Chelsea, and Revere. Both routes overlapped for the majority of their paths through East Boston and Revere, with their only divergence occurring near Wonderland. According to the network proposals from May and November 2022, route 117 was planned for elimination, with the portion between Broadway and Wonderland station incorporated as an extension of route 116, maintaining essential bus frequency. This adjustment was implemented on December 15, 2024.

See also

• List of MBTA bus routes
• MBTA crosstown bus routes
• MBTA Silver Line (previously included in key routes)
• Free public transport in Boston

External links

• MBTA – routes , , , , , , , , , , , , , ,
• MBTA - Key Bus Route Improvement Program