Green Line (MBTA)

The Green Line is a light rail system run by the Massachusetts Bay Transportation Authority (MBTA) in the Boston, Massachusetts, metropolitan area. It is the oldest MBTA subway line, and with tunnel sections dating from 1897, the oldest subway in North America. It runs underground through downtown Boston, and on the surface into inner suburbs via six branches on radial boulevards and grade-separated alignments. With an average daily weekday ridership of 101,000 in 2023, it is among the most heavily used light rail systems in the United States. The line was assigned the green color in 1967 during a systemwide rebranding because several branches pass through sections of the Emerald Necklace of Boston.

The four branches are the remnants of a large streetcar system, which began in 1856 with the Cambridge Horse Railroad and was consolidated into the Boston Elevated Railway several decades later. The branches all travel downtown through the Tremont Street subway, the oldest subway tunnel in North America. The Tremont Street subway opened its first section on September 1, 1897, to take streetcars off overcrowded downtown streets; it was extended five times  over the next five decades. The streetcar system peaked in size around 1930 and was gradually replaced with trackless trolleys and buses, with cuts as late as 1985. The new D branch opened on a converted commuter rail line in 1959. The Green Line Extension project extended two branches into Somerville and Medford in 2022.

Route description

The Green Line's core is the central subway, a group of tunnels which run through downtown Boston. The Tremont Street subway runs roughly north–south through downtown, with stations at , , , , and – all with connections to other lines of the MBTA subway system. The Boylston Street subway runs roughly east–west through the Back Bay neighborhood, with stations at , , , and ; it connects to the Tremont Street subway at Boylston. The Huntington Avenue subway diverges from the Boylston Street subway at a flat junction west of Copley, running southwest, with stations at and . A branch of the Tremont Street subway, disused since 1962, runs south from Boylston to the former Pleasant Street incline.

The Green Line has four western surface branches, each with a letter designation:

The B branch runs west in a tunnel from Kenmore, surfacing in the median of Commonwealth Avenue at . It runs on Commonwealth Avenue through Boston University, Allston, and Brighton to Boston College station.
The C branch runs southwest in a tunnel from Kenmore, surfacing in the median of Beacon Street at . It runs on Beacon Street through Brookline to Cleveland Circle station.
The D branch diverges from the C branch tunnel southwest of Kenmore, surfacing at Fenway station. It runs though Brookline and Newton along the grade-separated Highland branch (a former Boston and Albany Railroad commuter rail line) to Riverside station.
The E branch runs southwest through the Huntington Avenue subway from Copley, surfacing in the median of Huntington Avenue at Northeastern University station. It runs along Huntington Avenue and South Huntington Avenue to , with the outer (west of ) in mixed traffic rather than a dedicated median. Until 1985, the line continued south through Jamaica Plain to .

B and C branch service terminates at Government Center, while D and E branch service continues north from downtown Boston. North of North Station, the line inclines up to the Lechmere Viaduct, which crosses the Charles River with an elevated station at . The elevated Lechmere station is located on the Green Line Extension viaduct, which continues north to a flying junction with two branches:

The Union Square Branch runs west to Union Square station via the Fitchburg Line right-of-way. It is operated as part of the D branch.
The Medford Branch runs northwest to Medford/Tufts station via the Lowell Line right-of-way. It is operated as part of the E branch.

Former branches

The Green Line A branch was the northernmost of the branches, running from the Blandford Street portal (still used by the B branch), west to Watertown, mostly street-running. The bus replaced the streetcar line in 1969. The A branch diverged from Commonwealth Avenue west of Boston University and ran to a terminus in Watertown, across the Charles River from Watertown Square, until 1969. Although the route-letter scheme had been introduced two years prior to its closure, the "A" designation was never signed on streetcars to Watertown. It was, however, included in the destination signs on the Boeing-Vertol LRVs ordered in the mid-1970s, when reopening service to Watertown was under consideration. The "A" line tracks remained in non-revenue service to access maintenance facilities at Watertown until 1994.

The Pleasant Street portal hosted two services in its final days. Route to City Point ended in 1953; route to was cut back to Lenox Street in 1956, cut back to the portal in 1961, and ended operation in 1962. Prior to that, route 48 serviced Tremont Street to Dover Street and Washington Street, ending at , and last running in 1938.

The last two routes to continue beyond the Canal Street portal both ran to . The ran via Main Street, last running in 1948, and the via Bunker Hill Street last ran in 1949. Until 1997, trains continued to use the portal and its North Station surface station as a terminal.

In addition to the lines that later became the E branch, the Ipswich Street line split in Brookline, one branch running into the current "E" tracks and into the Boylston Street portal, and the other running up Brookline Street to end at Massachusetts Avenue station. These were truncated in 1932 into a shorter route from Brookline Village to the subway via the Boylston Street portal.

The last "foreign" cars to operate in the subway were those of the Eastern Massachusetts Street Railway, running from the Canal Street portal to the Brattle Loop at Scollay Square until 1935. It was then that the old Mystic River Bridge to Chelsea was closed to streetcars and the lines were replaced by bus service; the next year the Boston Elevated Railway (BERy) bought the Eastern Mass Chelsea Division and through-routed it with its lines connecting to the East Boston Tunnel at Maverick.

Rolling stock

Like the three other MBTA subway lines, the line uses standard gauge tracks. However, instead of heavy rail metro rolling stock, the Green Line uses modern streetcars (light rail vehicles) as heavy rail stock would be inappropriate for the surface branches with their numerous grade crossings.

Listing

Active fleet

Rolling stock :

Retired fleet

Only MBTA operated vehicles are included here, not cars from the Boston Elevated Railway era.

{| class="wikitable"

!Years in Service

!Manufacturer

!Model

!Image

!Length

!Width

!Fleet numbers

!Quantity

| 1976–2007

| Boeing Vertol

| US Standard Light Rail Vehicle

| 100px

| 3400–3543

| 144 (31 units cancelled)

| 1937–1985

| Pullman Standard

| PCC streetcar

| 100px

| 3000–3346

| 344 (2 cars scrapped before 1964)

Future

{| class="wikitable"

!Years Built

!Manufacturer

!Model

!Image

!Length

!Width

!Fleet numbers

!Quantity

|2027–2031

|CAF USA

|Type 10 LRV

|100x100px

|4001–4102

|102 (expected to enter service in 2027) Operations by several different companies were eventually consolidated into the Boston Elevated Railway, which ran a mixture of car types. After receiving a test unit in 1937, the BERy began to standardize on PCC streetcars, acquiring 320 units between 1941 and 1951 plus an additional 25 in 1959 to phase out the last older cars. Beginning in 1923, all streetcars on the system were painted orange for maximum visibility in traffic. In 1971, the MBTA began painting Green Line streetcars in a green and white scheme to match the new line name.

Two older streetcars are on display on the unused outer inbound track at Boylston station, which formerly carried cars coming from the Pleasant Street portal. Car #5734, a Type 5 A-1 car built in 1924 and retired in 1959, is owned by the Seashore Trolley Museum, but resides semipermanently in Boston. PCC #3295, built in 1951 and retired in 1986, is owned by the MBTA.

Boston (with its older streetcar tunnel systems) and San Francisco (with a new Muni Metro streetcar tunnel being built as part of BART construction) were chosen as the testbeds for this new rolling stock. The vehicle was designed as the largest rolling stock that would fit through the Tremont Street tunnel, the Muni Metro's Twin Peaks Tunnel, and SEPTA's subway–surface lines tunnel.

Desperate for reliable rolling stock, in 1977 MBTA launched an overhaul program to extend the availability of its older PCC cars. A total of 34 cars, primarily out-of-service wrecks and parts cars, were rebuilt to as-new condition.

Modern fleet

thumb|Type 7 (left) and Type 8 streetcars at Tappan Street in 2012

In the early 1980s, with a final settlement with Boeing in place, MBTA started looking for new equipment to supplement and replace the problematic LRVs.

In 1980, the MBTA tested Canadian Light Rail Vehicles for three months to determine whether they could be used on the Green Line. The MBTA ultimately found them unsuitable.

Ultimately, the MBTA purchased LRVs from the Japanese firm Kinki Sharyo. These Type 7 were designed with the best features of the US SLRV, the Canadian LRV, and the PCC cars. A total of 120 Type 7 vehicles were purchased, 100 were delivered between 1986 and 1988, and an additional 20 cars ordered and delivered in 1997.

Low-floor LRVs were added starting in 1998, allowing for accessible boarding directly from slightly raised platforms. MBTA ordered 100 of these Type 8 cars from Italian company AnsaldoBreda. One year later, in December 2005 the MBTA announced that it had entered into a restructuring of the deal, reducing the order to 85 cars (with spare parts to be provided in lieu of the 15 remaining cars), and providing for the remaining payment under the original deal only if the cars met performance requirements. Construction of the last car under the order was completed on December 14, 2006. Ultimately, 10 additional cars would be assembled and delivered in late 2007, with five spare shells retained (95 cars in service). The MBTA was criticized for their failure to assess Bredas' reliability before entering into the deal, and during delivery. The agency was also forced to spend an additional to modify tracks to prevent derailments and the Type 8 fleet was unable to be used on the D branch (where cars reach full speed) after those modifications were complete in 2008. Of the remaining cars, six were sold to the US Government and are now in Pueblo, Colorado for testing purposes, one was given to the Seashore Trolley Museum, and three were retained by the MBTA for work service.

In 2006, as part of a legal settlement, the MBTA committed to always operate at least one low-floor car in each train, with no trains consisting only of Type 7 cars. The cars were made by CAF USA, Inc., with the shells and frames made in Spain, and final assembly and testing done at their plant in Elmira, New York. , the first unit had been expected to enter passenger service in Spring 2018, with all 24 cars in service by the end of the year. The first Type 9 car, #3900, began revenue service on December 21, 2018.

Future fleet

thumb|left|A full-scale mockup of the planned Type 10 "Supercar" LRV

Planning for a Type 10 fleet—which would replace all Type 7 and Type 8 cars in the mid-2020s—began in 2018 with plans for a fully low floor fleet. At long, Type 10 cars would be significantly longer than the existing fleet, and carry twice as many passengers as existing cars. The MBTA released a request for proposals in December 2019, with notice to proceed expected to be given in 2021. In June 2021, the MBTA indicated that the initial order would be for 102 LRVs operating as single cars, with two-car trains deferred for a later project with federal funding. Manufacturer bids were due in July 2021.

The MBTA awarded an $811 million contract to CAF USA on August 31, 2022, to manufacture 102 seven-segment Type 10 "Supercar" LRVs. Four pilot vehicles were initially to be delivered in spring 2026, with deliveries of two LRVs per month from spring 2027 to spring 2031, though an update given in April 2026 pushed back the pilot vehicle delivery back to the end of 2026, with the other dates unchanged. The contract included options for additional LRVs. As a separately-funded project, Lake Street Yard will be fully reconstructed to support Type 10 vehicles, with Riverside Yard and the GLX Vehicle Maintenance Facility also modified. When the Type 10 cars are delivered, the Type 9 fleet is expected to be transferred over to the Mattapan Line, replacing the PCC streetcars.

Wheelchair lifts have been provided at some stops. They are rolled up to the car door and the lift mechanism is operated using a hand crank. They are quite time-consuming to operate, causing significant delays when used during peak periods.
Short platforms level with car floors, accessed by ramps, were installed just before or after selected stations. Because the car door arrangement required a large gap between the platform and the car, a bridge plate attached to the raised platform had to be positioned after the train stopped with a door at that platform.
The MBTA has followed the worldwide trend of operating low-floor streetcars. Platforms are being raised slightly to about the height of a street curb. Low-floor cars have remotely controlled bridge plates at the center doors to allow wheelchairs and strollers to reach the car floor a few inches higher. , the D branch will be the first branch to be completely retrofitted with raised platforms as part of this program.

History

Beginning in the 1850s, Boston sprouted a large network of horsecar lines, the first public transit in the city. The West End Street Railway was created by the state legislature in 1887 to build a single line, but soon consolidated many of the existing lines into a single privately owned system with consistent fares and route designations. The Allston – Park Square line (which served the general area of the A branch) was the first section to be converted to electric traction in 1889. It used modified existing horsecars outfitted with Frank J. Sprague's revolutionary electrical equipment, which had first been demonstrated the previous year in Richmond, Virginia. In 1897, the West End Street Railway property was handed over to the Boston Elevated Railway in the form of a 24-year lease, and the companies were ultimately combined.

By the early 1890s, the sheer quantity of streetcars during peak periods was clogging the streets of downtown Boston. The Tremont Street subway, the first passenger subway in North America, was opened in stages in 1897 and 1898, with underground stations at Boylston, Park Street, Scollay Square, Adams Square, and Haymarket. The Main Line Elevated was run through the tunnel from 1901, displacing through-running streetcars,

Unlike the MBTA's heavy rail subway lines, the Green Line has only limited central control and monitoring. This also means that it has lagged behind the other three rail lines in the availability of countdown signs and "next train" arrival information. The line is signalled with advisory wayside signals, except on surface portions in street medians or in-street running. Wayside signal territory stretches from Lechmere to the surface portals at Kenmore, and along the entire length of the D–Riverside branch. There are no automatic protection devices, but the cars have track brakes, giving the ability to stop quickly under control of the operator. Interlockings are controlled through a wayside Automatic Vehicle Identification (AVI) system that relies on the operator properly entering the destination manually on a roto-wheel in the train cab at the beginning of a run.

The line is monitored from the Operations Control Center (OCC). Responsibility for controlling service is shared by the control room and field personnel along the right of way. Track circuit and signal indications are not transmitted to the operational personnel sites. In lieu of track circuit indications, the AVI system is displayed in the control room to provide a periodic update to train position wherever AVI detectors exist. The AVI system user interface was solely text based until the current control room was opened, in which a new schematic display based on AVI data was instituted. Track circuit indications are available digitally in signal houses at the Park Street interlocking, at the new North Station interlocking, and at the new Kenmore interlocking, but are not transmitted to OCC. In January 2013, the MBTA announced plans to add full vehicle location tracking on the Green Line for countdown signs and smartphone applications, including using AVI data in the tunnels and GPS receivers on the surface lines. However, three-car trains suffered from reliability problems and slow boarding. The use of three-car trains ended in March 2016. The project was 28% complete by December 2021; installation of in-vehicle electronics was scheduled to be complete by September 2023, with wayside installation complete in June 2024 and full operation that December. A reallocation of funds in January 2022 shortened the project timeline, with completion expected in 2023. However, in January 2023, an NTSB report found that the project had been delayed to June 2025. The MBTA cancelled the contract in June 2024 citing a lack of progress and an inability by the contractor to complete the project.

The MBTA worked with a different contractor to develop the GLTPS-2 system in two phases. Phase 1, expected to be installed on the existing Type 7, Type 8, and Type 9 fleet by the end of 2025, will be an operator warning system with alarms that trigger when a train is exceeding speed limits or is at risk of imminent collision with another train. Phase 2, which will be installed only on the Type 9 and future Type 10 fleet, adds automatic enforcement by braking and is planned to be finished by June 2028. A $112.5 million contract to install the system was approved in February 2025.

Turnarounds

thumb|right|A D branch train on the loop at Kenmore station in 2024

Aside from the terminal stations, several locations have turnaround loops or crossover switches where trains can reverse direction for short turns. One of these, where northbound trains can turn southbound, is regularly used as the downtown terminal for two of the branches:

At , a loop under City Hall Plaza. , this is the terminal of the B and C branches.

Several other loops and crossovers are not used in regular revenue service but may be used during construction work or service disruptions, or for non-revenue trains, with some having been regularly used as terminals in the past:

At , a loop allows eastbound (inbound) C and D branch trains to turn westbound.
On the B branch, a pocket track at allows trains to reverse in either direction. It is sometimes used to reverse westbound trains to provide extra service in the subway. Occasionally-used crossovers are located at , , and east of .
On the C branch, occasionally-used crossovers are located at and .
On the D branch, occasionally-used crossovers are located west of , , , , , and . At Reservoir, the spur tracks to Reservoir Carhouse have platforms for short turn trains.
On the E branch, crossovers are located at , , and , along with a siding at Northeastern. The Brigham Circle crossover is frequently used for short turns during traffic congestion on the street-running section of the line.

Location tracking

thumb|left|Activated countdown signs at Kenmore station in August 2015

The Red, Orange, and Blue lines have block signalling systems that make tracking the location of trains easier. Signs in most station on those lines began to display real-time train information in late 2012 and early 2013, while data feeds have been available for smartphone applications since 2010. However, the wayside signalling system used in the Green Line's tunnels and the D branch does not provide for that level of tracking, nor do the basic stop/go signals used on the street-level branch lines. In January 2013, the MBTA announced plans to provide full tracking data for the Green Line by 2015, allowing use of smartphone applications and in-station countdown signs. On October 23, 2014, location tracking data became available for Green Line trains above ground. Arrival predictions for surface stations – including the activation of countdown signs along the D branch – and underground tracking and predictions were to be rolled out in two phases by early 2015. In March 2015, the MBTA announced that enough AVI equipment had been installed to allow the release of some underground data by April. Most underground data was live by August, but trains near Park Street and Boylston waited until September.

The first predictive countdown signs on the Green Line were activated at Newton Centre and Newton Highlands on April 24, 2015, followed shortly by other D branch stations. Countdown signs at Kenmore and Hynes were activated in August 2015. Signs at Copley and Arlington plus eastbound-only signs from Boylston through Science Park were activated in October 2015. The final set of signs – those on the westbound platforms of Science Park through Boylston – were activated in January 2016. Because holding and short-turning trains at the downtown terminals makes time-based predictions unreliable, the signs instead show how many stops away a train is.

Projects

Somerville/Medford extension

thumb|left|upright=1.25|Map of the Green Line Extension. Nearby parts of the Red Line and Orange Line are also shown.

The Green Line Extension (GLX) project added two new branches into the northern suburbs of Somerville and Medford. The project opened in two phases in 2022 at a total cost of $2.28 billion. The rebuilt Lechmere station and the Union Square Branch to opened on March 21, 2022, as an extension of the D branch (briefly the E branch). The Medford Branch opened to on December 12, 2022, as an extension of the E branch, with intermediate stations at , , , and . The total project cost is estimated to be $2.28 billion: $0.996 billion from the federal government and $1.28 billion from the state. Daily ridership on the extension is projected to be 45,000 by 2030.

The GLX begins at the north end of the Lechmere Viaduct, with a new elevated line continuing north for about parallel to the O'Brien Highway. The former surface-level Lechmere station was replaced by an elevated station on the new alignment. The two branches split with an aerial flying junction on the Red Bridge viaduct in the Inner Belt area. The Union Square Branch runs west from Red Bridge, sharing the Fitchburg Line right of way. The Medford Branch runs northwest from Red Bridge, sharing the Lowell Line right of way. Like the existing D branch, the new branches are fully grade-separated, with no level crossings. A new vehicle storage yard and maintenance facility is located in the Inner Belt area, with leads from both branches at Red Bridge. An extension of the Somerville Community Path runs along the Medford Branch south of Lowell Street, with a high bridge carrying it above the Red Bridge viaduct.

An extension north from Lechmere was first proposed in the 1920s, and again several times during the 20th century. In 1991, the state agreed to build a set of transit projects as part of an agreement with the Conservation Law Foundation (CLF), which had threatened a lawsuit over auto emissions from the Central Artery/Tunnel Project (Big Dig). Among the projects was an extension the Green Line from Lechmere to Medford Hillside through Somerville and Medford, two suburbs underserved by the MBTA relative to their population densities, commercial importance, and proximity to Boston. After delays in planning, the state agreed in 2006 to complete the project by 2014. The preferred alternative from the 2009 Draft Environmental Impact Report added the Union Square Branch; the Medford Branch terminus was set as College Avenue, with a potential future extension to .

The planned completion was delayed to 2018 in 2011, and to 2020 in 2014. A groundbreaking ceremony was held in December 2012. The project was expected to cost about $2.2 billion, with half of that paid by the Federal Transit Administration (FTA). However, in 2015 it became clear that the project would cost $3 billion, putting its future in doubt. The project was value engineered to reduce its cost: station designs were simplified, several bridge reconstructions eliminated, the Community Path extension shortened, and the maintenance facility reduced in size. The FTA approved the modified $2.3 billion plan on April 4, 2017. The contract was rebid with a provision for the optional restoration of six of the elements deleted in the 2016 plan. The winning bid, selected in November 2017, included six optional elements, including canopies and additional elevators at stations, public art, a full-size vehicle maintenance facility, and the full extension of the Community Path to East Cambridge. Construction reached 20% completion in November 2019; it was over 50% completed by October 2020, and 80% by June 2021.

Accessibility renovations

thumb|right|Government Center station under reconstruction in September 2014

The majority of the Green Line opened by 1959, long before the 1990 Americans with Disabilities Act mandated that new construction be fully accessible. The MBTA began modifying Red, Orange, and Blue Line stations for accessibility in the late 1980s; however, Green Line stations were not modified until the late 1990s, when the Type 8 vehicles were under construction. The MBTA began the Light Rail Accessibility Program in 1996. Because modifying the numerous stations all at once would be prohibitively expensive, the MBTA designated "key stations" – largely those with high ridership or bus connections – for prioritization.

Riverside station was completely rebuilt with raised accessible platforms around 1998. and (both of which already had elevators from previous projects) were outfitted with portable lifts for temporary accessibility around 2000, as were and ten surface stations. The 13 B, C, and E branch stations collectively cost $32 million. Construction of raised platforms was completed at Park Street and Haymarket around 2003; Prudential was also reconstructed that year by the developer of 111 Huntington Avenue. The fully accessible underground "superstation" at North Station opened in 2004.

Renovations for accessibility were completed at in 2009, and in 2010, and in 2011. A two-year closure of ended in 2016 with the opening of the accessible transfer station. As part of the Green Line Extension, Lechmere was replaced by a fully accessible elevated station in 2022. (with renovations in design) and are the other remaining inaccessible stations in the Central Subway. , the MBTA does not expect to make Boylston accessible by 2030, while Hynes is dependent on funding availability.

Other projects have moved towards full accessibility of the surface branches. was made accessible in 2006. Renovations completed in 2009 made accessible and replaced the lifts at and . A reconstruction of (replacing lifts) was completed in 2022. Construction of two accessible stations ( and ) on the B branch to replace four non-accessible stations took place in 2021. Temporary work to make accessible was done in 2019, followed by the four remaining D branch stations in 2024; larger reconstructions of the five stations are planned for later in the 2020s.

The nine remaining non-accessible B branch stations are to be reconstructed in 2026–2027. Consolidations will reduce the nine stops to six.
Signal upgrades, new crossovers, and other work in the Central Subway
Systemwide overhead catenary relocation
Traction power improvements on the D Branch
Modifications to the Riverside, Reservoir, Lake Street, and Inner Belt yards
Accessibility and infrastructure work on the B and E branches
58 additional Type 10 vehicles
A test track between Chestnut Hill and Newton Centre for Type 10 vehicles
Upgrades to a Type 10 simulator for operators

Station listing

This listing includes only the Green Line section between and , which are served by multiple branches. For stops served by only one branch, see , , , and . All stations in the central subway have prepaid fare areas (fare control).

{| class="wikitable"

!Location

!Station

!Branches

!Opened

!Notes and connections

|East Cambridge

|rowspan=4|D, E

|March 21, 2022

|The Lechmere Viaduct opened on June 1, 1912, with a direct connection to surface lines until July 9, 1922. The surface station was open from July 10, 1922, to May 23, 2020. :

|West End

|August 20, 1955

|rowspan=2|North End

|June 28, 2004

|Original surface station was open from September 3, 1898, to March 27, 1997. Elevated station was open from June 1, 1912, to June 24, 2004. : : Fitchburg, Lowell, Haverhill, Newburyport/Rockport : :

|rowspan=2|September 3, 1898

|: :

|rowspan=3|Downtown Boston

|rowspan=5|B, C, D, E

|: :

|rowspan=2|September 1, 1897

|: , () : At : ;

|: () :

|rowspan=3|Back Bay

|November 13, 1921

|rowspan=2|October 3, 1914

|rowspan=2|B, C, D

|Fenway–Kenmore

|October 23, 1932

|: At :

Incidents and collisions

thumb|left|Type 7 LRV car wrecked in the May 2008 crash

On May 28, 2008, two D branch trains collided in Newton. The operator of one of the trains was killed and numerous riders were taken to area hospitals with injuries of varying degrees of seriousness. While it was originally thought that cell phone use was responsible for the crash, the cause was officially determined to be an episode of micro-sleep caused by the driver's sleep apnea.

On May 8, 2009, two trolleys rear-end collided underground between Park Street and Government Center when the driver of one of the trolleys, 24-year-old Aiden Quinn, was text messaging his girlfriend while driving. Quinn had run through a red light before the crash, which injured 46 people. MBTA officials estimated that the cost of the crash was $9.6 million. A strict ban on cell phone usage by MBTA operators was later enacted.

On October 8, 2012, two E branch trolleys collided in the 700 block of Huntington Avenue near Brigham Circle when one derailed into the other, injuring three people including a train operator. The next month on November 29, two trolleys collided at low speed at Boylston, injuring several dozen passengers.

On March 10, 2014, a D branch trolley with passengers aboard derailed in the tunnel just west of Kenmore Station, near the flat junction between the "D" and "C" branches. A second train had to brake suddenly to avoid hitting the derailed train. Ten people were treated for moderate injuries.

In October 2016, The Boston Globe reported that the Green Line had the highest number of derailments and collisions on light rail lines in the United States in 2015. The number of incidents had been increasing for several years due to deferred maintenance on tracks and wheels, which resulted in more low-speed derailments of Type 8 cars.

On July 30, 2021, two B branch trains collided at , causing 25 injuries.

On October 1, 2024, a train derailed near Lechmere, injuring seven people and disrupting service on the Green Line Extension. Regular service resumed on October 3. The National Transportation Safety Board, Federal Transit Administration, and Massachusetts Department of Public Utilities are investigating the derailment. A preliminary NTSB report noted the train was going in a zone and passed through a double red signal that required a stop. The train passed through a switch that was still moving into position, causing part of the first truck of the lead car to go straight and the rest of the train into the diverging track and causing the derailment.

On February 9, 2025, a E branch train crashed into an out of service train at East Somerville, injuring five people.

In 2009, the National Transportation Safety Board recommended that the Green Line be outfitted with positive train control to prevent collisions as part of its various crash investigations. The MBTA decided in 2012 not to implement PTC, estimating the cost at $645 million to $721 million. In 2015, as crashes continued to happen, the NTSB complained the agency was moving too slowly identifying a feasible alternative. In 2019, the MBTA awarded a contract to implement a similar safety system by 2024, at a cost of $170 million. A train would automatically brake if a driver violated a traffic signal, or if cameras or radar detected an obstacle. That contract was cancelled in June 2024.

References

External links

MBTA – Green Line