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 Boston subway line, with tunnel sections dating to 1897. It runs underground through downtown Boston, and on the surface on several radial boulevards and into inner suburbs. With a daily weekday ridership of 210,000 in early 2014, it is the second most heavily-used light rail system in the country. 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 begun in 1856 with the Cambridge Horse Railroad and was consolidated until the Boston Elevated Railway several decades later. The Tremont Street Subway – the oldest subway tunnel in North America - 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. A new branch opened on a converted commuter rail line in 1959; the Green Line Extension project will add two new branches into Somerville and Medford in 2017 and 2019.

Description
The line has its northern terminus at Lechmere in eastern Cambridge with connections to numerous bus routes serving Cambridge and Somerville. From there it runs south over the Lechmere Viaduct and into an extension of the Tremont Street Subway under downtown Boston to the Boston Common. It continues west in the Boylston Street Subway to Kenmore Square. The Green Line tunnels through Downtown Boston and the Back Bay are collectively referred to as the Central Subway.

The "E" Branch serves Lechmere and splits just west of Copley, running southwest through the Huntington Avenue Subway, ramping up to the surface at Northeastern University near Boston's Symphony Hall. It continues along Huntington Avenue, and terminating at Heath Street near V.A. Medical Center. Until 1985, the line continued though Jamaica Plain to Arborway.

The "B", "C", and "D" Branches diverge west of Kenmore Square. From south to north, they are as follows:

The "D" Branch surfaces onto the grade-separated Highland Branch, a branch of the Boston and Albany Railroad until 1958. It runs about ten and a half miles to Riverside, the primary light rail maintenance facility and major park and ride facility, on the banks of the Charles River and half a mile from the interchange of I-90 (Massachusetts Turnpike) and I-95 (Route 128 Circumferential Highway).

The "C" Branch surfaces onto Beacon Street, running to Cleveland Circle at the Chestnut Hill Reservoir.

The "B" Branch surfaces onto Commonwealth Avenue. It runs past Boston University, passes within a quarter mile of Cleveland Circle, where a connection to the latter runs down Chestnut Hill Ave., and continues to Boston College.

The "A" Branch diverged from Commonwealth Ave. west of Boston University and ran to 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 Watertown was under consideration. The A line tracks remained in non-revenue service to access maintenance facilities at Watertown until 1994. Not only was there community opposition to restoration, but the tracks would have required a complete rehabilitation.

The Lechmere Viaduct originally connected to the Central Subway via the Causeway Street Elevated, a half-mile-long structure running in front of North Station and the Boston Garden sports complex. A new tunnel, running behind North Station and the new TD Garden (which replaced the Boston Garden) and connecting to a new underground Green Line and Orange Line transfer station, was built to replace it. Bus shuttle service ran from Government Center (Scollay Square) to Lechmere from June 2004 until November 12, 2005 during the final stages of construction.

The original Tremont Street Subway south of Boylston station has been closed since 1962, when the last streetcar line feeding into it was replaced by bus service, and Pleasant Street Portal at its southern end has been covered over. Reuse of part of the tunnel for the Silver Line Phase III was briefly considered, but the narrow bore was found too small for the Silver Line buses which (unlike trolleys) are not fixed to their guideway. Plans for the Phase III tunnel were shifted further west to new alignments, then canceled due to questions over the project's cost-effectiveness.

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.

Active fleet
Rolling stock :

Retired fleet
(Only MBTA operated vehicles included, not cars from the Boston Elevated Railway era)

Future fleet
Twenty-four new Type 9 Green Line cars are due to be delivered starting in 2017, with all cars delivered by 2019. The Type 9 cars will provide additional rolling stock to allow for Green Line Extension operations, and will not replace any of the existing fleet. The cars will be made by CAF USA, Inc.; the shells will be made in Spain, while final assembly and testing will be done at their plant in Elmira, New York.

Early rolling stock
When it opened at the end of the 19th century, the Tremont Street Subway was not intended as a full-scale rapid transit line (though it was built to pre-metro standards), but to allow ordinary streetcars to bypass the worst street congestion in downtown Boston. 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.

Boeing LRV
In the early 1970s, light rail—which had largely disappeared from North America after the slow decline of streetcar systems from the 1920s to the 1950s—was reintroduced as a method of urban renewal less expensive than conventional metro systems. In 1971, as part of a program to supply further work to defense contractors as the Vietnam War wound down, the Urban Mass Transit Administration selected Boeing-Vertol as systems manager for a project to design a new generation of generic light rail vehicle.

After a 1972 report by Vukan Vuchic, Boston (with its older streetcar tunnel) 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, intended to jumpstart similar systems in other cities. The US Standard Light Rail 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. The new cars were faster—a top speed of 50 mph versus the PCC's 36 mph—and had an articulated middle section for higher capacity. Boeing began construction of 175 cars for the MBTA in May 1973.

The first LRVs entered service on the "D" Branch in December 1976 but were immediately beset with problems. Certain cars frequently derailed on tight turns in the Riverside, Boston College and Lechmere yards. Battery trays, air conditioners, and air compressors suffered numerous failures; the plug-style doors had trouble sealing properly; and traction motors failed sooner than expected. Desperate for reliable rolling stock, the MBTA launched an overhaul program to extend the availability of its older PCC cars. A total of 15 cars, primarily out-of-service wrecks and parts cars, were rebuilt to as-new condition.

, ten of the rebuilt PCC cars still run on the Ashmont-Mattapan section of the Red Line, because maintaining the small PCC fleet is less expensive than rebuilding the rail line for modern light rail or heavy rail stock. Because these heritage streetcars operate exclusively on a dedicated right of way which has only 2 grade crossings (instead of using street running), they are less exposed to collisions in mixed road traffic.

Modern fleet
In 1987, 100 second generation (Type 7) LRVs were ordered from the Japanese firm Kinki Sharyo, with an additional 20 cars ordered and delivered in 1997. The first low-floor Green Line streetcars, allowing for handicapped-accessible boarding directly from slightly raised platforms, were the Type 8 cars from AnsaldoBreda which began arriving in 1998. The first Type 8s entered revenue service in 1999, but they were prone to derailment at higher speeds as well as brake problems; not until 2008 did they assume full service on the "D" Branch (where they reach full speed).

As the final Type 8s were delivered, the last of the Boeing-Vertol cars were retired in March 2007, and all except for ten of the cars were scrapped. 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. , the Kinki Sharyo cars made up the bulk of rolling stock, alongside the newer Breda cars.

86 of the 120 Type 7 cars are being overhauled by Alstom in Hornell, New York. The work, scheduled to be complete by October 2016, includes new propulsion systems, climate control systems, and interiors as well as exterior work. The pilot car for the program, #3614, left in October 2012 and was returned to the MBTA in November 2014.

As part of the Green Line Extension project, 24 third-generation Type 9 LRVs will be acquired to increase the fleet size to allow for service on the expanded network. Should finances permit, more Type 9 cars will be acquired to replace the aging Type 7 fleet.

Display cars
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. The cars were formerly used for fantrips, the most recent in 1997, but are no longer functional. The cars were heavily vandalized on January 14, 2014, but the vandalism was fully removed the next day.

The San Francisco Muni Metro runs a variety of PCC cars in various paint schemes on its F Market heritage line. #1059 is painted in Boston Elevated Railway colors, but that individual car never ran in Boston.

Accessibility
The Red Line, Blue Line, and Orange Line run rapid transit cars and use stations with high platforms level with the car floor providing easy access for the disabled. The Green Line is a trolley/streetcar line and has used a variety of streetcars.

Originally all the Green Line stations had platforms at track level, and passengers had to ascend several steps up into the vehicles. This limited accessibility for persons with disabilities. To address this issue and comply with changing federal and state laws, additional facilities have been added:

One hundred low-floor cars were purchased from the Italian company AnsaldoBreda, with styling by Pininfarina. They were initially problematic and difficult to maintain: the first cars failed every 400 miles (640 km), far less than the 9,000 miles (14,500 km) specified by the MBTA, and were prone to derailments. The MBTA has been forced to spend an additional US$9.5 million to modify tracks to prevent the derailments, echoing early problems with the Boeing stock. The MBTA has been criticized for their failure to assess Bredas' reliability before entering into the deal, and during delivery.
 * Wheelchair lifts have been provided at some stops. They rolled up the car door and the lift mechanism was 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. As an ongoing project, not complete in 2012, 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.

In December 2004, the MBTA canceled orders for the cars still to be delivered as part of the authority's nine-year, US$225 million-dollar deal with Breda. 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 meet performance requirements. Construction of the last car under the order was completed on December 14, 2006; though in late 2007 the MBTA announced it had contracted with Breda to deliver another 10 cars, bringing the total order to 95 production cars and 5 car shells for parts.

After several years of modifications to "D" Branch tracks, the Breda cars returned to service on that line, and now provide service on every branch of the Green Line.

The MBTA typically runs single cars and two- or three-car trains. Occasional four-car trains have been seen on special occasions such as after a baseball game at Fenway Park. , single-car trips are rare on weekdays. Two-car trains now run from the start to end of service Monday through Friday, with three-car trains on some rush-hour trips on all branches. The MBTA has promised that each two- and three-car train will contain at least one Type 8 low-floor car to facilitate access for disabled persons.

Operations and signalling
Unlike the MBTA 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. The first real-time data - location data on the surface lines - became available in October 2014. Full tracking is expected by early 2015.

Turnarounds
Trains can reverse direction at a number of stations where a turnaround loop is installed. In addition, there are a number of crossover switches where a train can cross to the opposite track and reverse its direction.


 * Lechmere is currently the northern terminus of the Green Line, and consists of a balloon-shaped turnaround.
 * At North Station, trains heading westbound/outbound toward Lechmere can turn around. No turnaround is available in the eastbound/inbound direction.
 * At Government Center, Green Line trains entering from either the east or west can turn around.
 * At Park Street trains can turn around in one direction only. Trains headed toward Lechmere upon entering Park Street on the inside track can turn around on a tight loop and end up on the so-called "fence track". This is a track that takes trains westbound, normally to Boston College and Heath Street.
 * Kenmore is where inbound trains coming from the Cleveland Circle or the Riverside Branches can turn around to the outbound track that takes trains to Cleveland Circle or Riverside. No turnaround is available for the "Boston College"/"Commonwealth Avenue" Branch.

Plans to reinstitute a crossover for through movements from the terminating (inner) northbound platform at Park Street to continue onwards towards Government Center are expected to increase capacity. However, this project was placed on hold in 2013 due to the cost of adding additional structural supports.

Somerville/Medford extension (Green Line Extension Project)
To settle a lawsuit with the Conservation Law Foundation to mitigate increased automobile emissions from the Big Dig, the Commonwealth of Massachusetts agreed to extend the line from its northern terminus at 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. The line would use railroad rights-of-way that serve the Lowell Line (which also carries Amtrak's Downeaster) and the Fitchburg Line of MBTA Commuter Rail. The extension is projected to have a total weekday ridership of about 52,000.

The Green Line Extension (GLX) is planned to have two branches, which will split just past a relocated Lechmere station. The Medford Branch, which will become an extension of the "E" Branch, will run along the Lowell Line right of way with stops at Brickbottom, Gilman Square, Lowell Street, Ball Square to College Avenue in Medford, on the edge of the Tufts University campus. The original plans called for a further station, Route 16, at the Mystic Valley Parkway in West Medford, but this station was placed on hold due to cost issues. The Union Square branch will follow the Fitchburg Line right-of-way from Lechmere to Union Square station just south of Union Square in Somerville.

In 2010, the Massachusetts Department of Transportation (MassDOT) announced that the new service was expected to be operational in October 2015; interim air quality offset measures would need to be taken if the project misses its December 2014 deadline as expected. In August 2011, MassDOT announced that opening of the Extension would be postponed to Fall 2018 at the earliest, with some stations not opening until 2019. The stated reason was difficulties in land acquisition, plus implied concerns about cost controls and financing. Interim air-quality improvement measures will be necessary due to the project delays. Possibilities include extending Green Line branches to Lechmere, increased bus service in Somerville and Medford, and temporary or permanent commuter rail stops along the GLX corridor. In September 2014, the target date for start of service was pushed back to 2020.

On June 11, 2012, the Federal Transit Administration approved the Extensions for entry into the Preliminary Engineering phase as part of the New Starts program. This approval was a necessary step in MassDOT's application for $557.06 million in New Starts funding.

A groundbreaking was held at the Medford Street bridge on December 11, 2012. A Notice to Proceed was issued to the contractor, Barletta Heavy Division, Inc., on January 31, 2013.

Arborway restoration cancelled
Another mitigation project in the initial lawsuit settlement was restoration of service on the "E" Branch between Heath Street and Arborway/Forest Hills. After some internal and community opposition, a revised settlement agreement resulted in the substitution of other projects with similar air-quality benefits. In lieu of the rail project, the state undertook to speed the Route 39 bus by improvements such as consolidating bus stops, lengthening stops, and re-timing traffic lights, funded by the federal American Recovery and Reinvestment Act of 2009 and expected to be completed in 2010. The last lawsuit mandating the return of rail service on this route was defeated in court in January 2011.

Light Rail Accessibility Project (LRAP)
All of pre-pay stations on the line opened between 1897 and 1959, long before the 1990 Americans with Disabilities Act. (However, the underground platforms at North Station were entirely new construction; they replaced the former elevated station in 2004.) Since the late 1980s, the MBTA has been adding elevators and rebuilding stations for ADA compliance. Most of the pre-pay stations are now handicapped accessible, and the MBTA is planning to renovate the remainder. "Key stations" on the surface branches were also made accessible around 2002 by raising platforms to match the new low-floor trains.

The following pre-pay stations have been made fully accessible:
 * Science Park: 2011
 * North Station: 2004 (2004-built underground station)
 * Haymarket: 2000 (1971-built station)
 * Park Street: 1993
 * Arlington: 2009
 * Copley: 2010
 * Kenmore: 2010
 * Prudential: 2003
 * Riverside: 2000

A major renovation of Government Center, including a new headhouse and redundant elevators to serve the Green and Blue lines, is under way. On March 22, 2014, the station was closed for this reconstruction project, expected to last two years. Accessibility renovations at Symphony and Hynes Convention Center are currently in preliminary design. Lechmere station will be replaced with an accessible elevated station opening in 2017 as part of the Green Line Extension project.

Location tracking
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. The $15 million system will use existing Automatic Vehicle Identification (AVI) systems plus additional sensors in the tunnels, and GPS receivers on the surface sections.

In September 2013, the MBTA announced that "Next Train" signs would be unveiled at Kenmore that month. On October 23, 2014, location tracking data became available for Green Line trains above ground. Arrival predictions for surface stations will be available by December 2014, including the activation of countdown signs along the "D" Branch. Underground tracking and predictions will be available in early 2015, completing the three-phase activation.

Station consolidation and rebuilding
Consolidation of four stations into two on Commonwealth Avenue along the "B" branch (to Boston College) is being studied, as part of a longterm plan to speed service and provide improved access on that line. The proposed new stations are expected to be fully compliant with ADA guidelines for handicapped accessibility, and to provide other amenities for all passengers.

Fare prepaid station listing
The following stations have prepaid fare areas (also called fare control), to allow quick boarding and exiting through front and rear doors. At all other stations, passengers must stand in line and use the front door to pay fares, slowing travel times especially during peak periods. At non fare control stops, an MBTA policy of forcing exiting passengers to also use the front doors (to prevent other riders from entering without paying) causes further congestion and delays.

Incidents and accidents


On May 28, 2008, two "D-line" trains collided in Newton. The operator of one of the trains was killed and numerous riders were taken to hospital with injuries of varying degrees of seriousness. While it was originally thought that cell phone use was responsible for the accident, 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-line" 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-line" trolley with passengers aboard derailed in the tunnel just west of Kenmore Station, near the flat junction between the Riverside (D) and Beacon Street (C) lines. A second train had to brake suddenly to avoid hitting the derailed train. Ten people were treated for moderate injuries. On August 18, 2014, a "B-line" train partially derailed near Kenmore station causing major delays, though no people were injured.