Initial attempts station through which the Second Avenue Subway was to have passed. After
World War I, the
New York City Subway experienced a surge in ridership. By 1920, 1.3 billion annual passengers were riding the subway, compared to 523 million annual riders just seven years before the war. In 1919, the
New York Public Service Commission launched a study at the behest of engineer Daniel L. Turner to determine what improvements were needed in the city's
public transport system. Turner's final paper, titled
Proposed Comprehensive Rapid Transit System, was a massive plan calling for new routes under almost every north-south Manhattan avenue, extensions to lines in
Brooklyn and
Queens, and several crossings of
the Narrows to
Staten Island. Among the plans was a massive trunk line under Second Avenue consisting of at least six tracks and numerous branches throughout Brooklyn, Queens, and
the Bronx. The
Second and
Third Avenue elevated lines were to be knocked down to make room for the 6-track subway. The paper was revised in January 1927. The
Great Depression began that year and the soaring costs of the expansion became unmanageable. Construction on the first phase of the IND was already behind schedule, and the city and
state were no longer able to provide funding. This scaled-down plan was postponed in 1931. In 1944, BOT superintendent Philip E. Pheifer put forth a proposal for Second Avenue Subway services, which would branch extensively off to
B Division. In 1948, New York City was short $145 million of the $800 million program needed for rehabilitation and proposed capital improvements. The City petitioned the New York State Legislature to exceed its $655 million
debt ceiling so that the city could spend $500 million on subway construction, but this request was denied. The cars featured
porthole style round windows and a new
public address system. Reflecting
public health concerns of the day, especially regarding
polio, the R11 cars were equipped with
electrostatic air filters and
ultraviolet lamps in their ventilation systems to kill germs. Money from the 1951 bond measure was diverted to buy new cars, lengthen platforms, and maintain other parts of the aging New York City Subway system. Out of a half-billion-dollar bond measure, only $112 million (equivalent to $ in ), or 22% of the original amount, went toward the Second Avenue Subway. and was demolished in 1956. Separately, in 1967, voters approved a $ (worth about $ in current dollars) Transportation Bond Issue, which provided over $ (worth $ today) for New York City projects, including for a 1968
Program for Action. The City secured a $25 million
Urban Mass Transportation Act (UMTA) grant for initial construction. The Second Avenue project, for a line from 34th Street to the Bronx, was given top priority. The Second Avenue line was criticized as a "rich man's express, circumventing the
Lower East Side with its complexes of high-rise low- and middle-income housing and slums in favor of a
silk stocking route." and 96th Street. The MTA issued a plan for a spur line, called the "cuphandle", to serve the heart of the Lower East Side. Branching off from the IND Sixth Avenue Line near the Second Avenue station, the spur would run east on Houston Street, turn north on Avenue C, and turn west on 14th Street, connecting to the
BMT Canarsie Line. In June 1972, it was announced that UMTA would grant $25 million for the construction of this section of the line. The MTA had requested $254 million in federal funds for the northern part of the line. Preliminary estimates of the cost of the southern portion of the line came to $450 million. Construction on a tunnel segment between 99th and 105th Streets began in October 1972. A second segment between 110th and 120th Street in
East Harlem started construction in March 1973. In October 1973, the line's
Chinatown segment began construction at
Canal Street under the foot of the Manhattan Bridge between Canal and Division Streets. A fourth segment started construction in July 1974, between Second and Ninth Streets in the
East Village. In total, construction on the Second Avenue Line during the 1970s spanned over 27 blocks. When plans were finalized in 1971, the subway had been proposed for completion by 1980, In December 1974, New York City mayor
Abraham Beame proposed a six-year transit construction program that would reallocate $5.1 billion of funding from the Second Avenue Line to complete new lines in Queens and to modernize the existing infrastructure, which was rapidly deteriorating and in dire need of repair. Beame issued a stop-work order for the line in September 1975, whereupon construction of the section between Second and Ninth Streets was halted, and no other funding was allocated to the line's construction.
1990s plans With the city's economic and budgetary recovery in the 1990s, there was a revival of efforts to complete construction of the SAS. Rising ridership on the
IRT Lexington Avenue Line, the only subway trunk line east of
Central Park, demonstrated the need for the Second Avenue Line, as capacity and safety concerns rose. This is more than the daily ridership of the second-busiest subway system in the U.S., the
Washington Metro, as well as more than the combined daily riderships of
San Francisco's and
Boston's transit systems. Local
bus routes are just as crowded during various times of the day, with the parallel
M15 local and
M15 Select Bus Service routes seeing 46,000 passengers per weekday in 2016, translating to 14.5 million passengers that year. In 1991, then-New York Governor
Mario Cuomo allocated $22 million to renew planning and design efforts for the Second Avenue line, but two years later, the MTA, facing budget cuts, removed these funds from its capital budget. In 1995, the MTA began its Manhattan East Side Alternatives (MESA) study, both a MIS and a DEIS, seeking ways to alleviate overcrowding on the Lexington Avenue Line and improve mobility on Manhattan's East Side. Second Avenue was chosen over First Avenue for logistical reasons. A spur to
Grand Central Terminal was considered, but later dropped. In December 2001, the
Federal Transit Administration approved the start of preliminary engineering on a full-length Second Avenue Subway. The final plan called for the full-length Second Avenue line to carry two services: the
T, with a route emblem colored , The Its construction site was designated as being from 105th Street and Second Avenue to 63rd Street and Third Avenue.
Deep bore tunneling methods were to be used in order to avoid the disruptions for road traffic, pedestrians, utilities and local businesses produced by
cut-and-cover methods of past generations. Stations were to retain cut-and-cover construction. The total cost of the line is expected to exceed $17 billion. In 2014,
MTA Capital Construction President Dr. Michael Horodniceanu stated that the whole line may be completed as early as 2029, and would serve 560,000 daily passengers upon completion. As of December 2016, only Phases 1 and 2 would be completed by 2029. The line is described as the New York City Subway's "first major expansion" in more than a half-century. It would add two tracks to fill the gap that has existed since the elevated Second and Third Avenue Lines were demolished in the 1950s.
Phase 1 construction New York voters passed a transportation bond issue in November 2005, allowing for dedicated funding allocated for that phase. Its passage had been seen as critical to its construction, but the bond was passed only by a narrow margin, with 55% of voters approving and 45% disapproving. At the time, the MTA said that the project would be done in 2012 In December 2006, the
United States Department of Transportation (USDOT) announced that they would allow the MTA to commit up to $693 million in funds to begin construction of the Second Avenue Subway and that the federal share of such costs would be reimbursed with FTA transit funds, subject to appropriations and final labor certification. The USDOT also later gave $1.3 billion in
federal funding for the project's first phase, to be funded over a seven-year period. Preliminary engineering and a final tunnel design was completed by a
joint venture between
Aecom and
Arup. In March 2007, upon completion of preliminary engineering, the MTA awarded a contract for constructing the tunnels, a launch box for the
tunnel boring machine (TBM), and access shafts to S3, a joint venture of Schiavone Construction,
Skanska USA Civil, and J.F. Shea Construction. A ceremonial groundbreaking took place on April 12, 2007, at the 99th Street tunnel segment built in the 1970s. Actual construction work began on April 23, 2007. At the time, it was announced that passengers would be able to ride trains on the new line by the end of 2013. Due to cost increases, several features of the subway were cut back soon after construction started: for instance, the 72nd Street station was downsized. In 2009, contracts were awarded for the
96th Street station box, as well as for excavation around the 86th Street stations. The TBM began boring the western tunnel southward from 96th Street in 2010. Contracts for tunnels to the
Lexington Avenue–63rd Street station, and for the excavation of the 72nd Street station, were awarded in 2010. The following year, contracts were awarded for excavation of the cavern at the 86th Street station, as well as construction for the Lexington Avenue–63rd Street station. The TBM, digging at a rate of approximately per day, finished its run at the planned endpoint under 65th Street on February 5, 2011, and started digging the eastern tunnel. On March 28, 2011, S3, having completed its task of completing the west tunnel to 65th Street, began drilling the east tunnel to the
bellmouth at the existing
Lexington Avenue–63rd Street station. The portion of the west tunnel remaining to be created was then mined using conventional drill-and-blast methods. In September 2011, the TBM completed its run to the Lexington Avenue–63rd Street station's bellmouth. In July 2013, the MTA opened a
Second Avenue Subway Community Information Center for Phase 1 at 1628 Second Avenue between 84th and
85th Streets. In the three years that followed, the center was visited over 20,000 times. The final contract for Phase 1 was awarded in June 2013. Blasting for the station caverns was finished in November 2013, and the muck houses were taken down at around the same time. In late 2013, many of the tracks and signal panels began to arrive at the construction site, to be installed on the line over the next few years. In February 2016, the MTA allocated $66 million to speed up the construction of the first phase so that it could open in December. Concerns about the line's timely opening persisted through October and November. Test trains started running on October 9, 2016, and out-of-service Q trains started running through the subway in November 2016. The new Third Avenue entrance to the Lexington Avenue–63rd Street station opened on December 30, 2016. The ceremonial first train, with several prominent officials in attendance, ran on New Year's Eve, and regular service began at noon the next day. Because of the opening of Phase 1, ridership on the Lexington Avenue Line at the
68th Street,
77th Street,
86th Street, and
96th Street stations decreased in January 2017 compared to January 2016. The Second Avenue Line's three stations and the renovated Lexington Avenue–63rd Street station saw an average weekday ridership of more than 150,000 by the end of January. The 72nd Street station was the busiest of the line's new stations, with an average daily ridership of 44,000. By April, taxi usage in the area also saw a decline of more than 20% compared to before the line's opening. By February 2018, there were 190,000 riders per weekday, within the 5% margin of error for the 200,000-daily-rider estimate given in the Environmental Impact Statement. Rush-hour ridership was within 2% of projections. In November 2017, because of the increasing demand, Q service was increased by one trip during each rush hour, and one northbound R trip was rerouted from the
IND Queens Boulevard Line to further boost service. This trip returns southbound in Q service. Three new stations will be constructed at 125th Street, 116th Street and 106th Street. A transfer to the Lexington Avenue Line and an intermodal connection with
Metro-North Railroad would be available at the Harlem–125th Street station. while tail tracks would continue north on a spur via Second Avenue to 129th Street. However, the tail tracks to 129th Street, as well as a proposed ancillary building at 127th Street and Second Avenue, were removed in a June 2018 update to the plans. A bellmouth provision for extension to the Bronx remains, North of 120th Street, the line will be constructed by TBMs. South of 120th Street, the line will utilize the 99th–105th and 110th–120th Streets tunnel sections built during the 1970s, with a cut-and-cover tunnel connecting the segments between 105th and 110th Streets. By August 2017, preliminary work on the line was underway, and design of the project was being performed by Phase 2 Partnership, a joint venture of Parsons-Brinckerhoff and STV. The EIS and design were finished in 2018. The
administration of Joe Biden approved funding for Phase 2 of the Second Avenue Subway in November 2021, and land acquisition for Phase 2 started in April 2022. The MTA began soliciting bids for the first construction contracts in July 2023. The MTA awarded a contract for utility relocations in January 2024, In August 2025, the MTA board awarded a $1.97 billion contract for the construction of tunnels for the northern section of Phase 2 to Connect Plus Partners, a
joint venture between Halmar International and
FCC Construction.
125th Street Subway – crosstown to Broadway In 2023, the MTA considered extending the line westwards from the Phase 2 terminus of 125th Street in their 2023 Twenty-Year Needs Assessment. An extension to Broadway was considered to deliver "significant benefits". In January 2024,
Governor of New York Kathy Hochul announced that the MTA would begin studying a western extension of the line, with three new stations on 125th Street at
Malcolm X Boulevard,
St. Nicholas Avenue and
Broadway. This was estimated to cost around $7.6 billion, however savings could be made by constructing the tunnels concurrently with Phase 2. To navigate the "mixed-face" geology of 125th Street—a complex layer of loose sand, gravel, and high water tables—the study recommended using pressurized tunnel boring machines, digging a tunnel up to deep beneath existing subway tunnels. In March 2026, the MTA's Capital Program Committee advanced a $1.1 billion construction contract for Phase 2.
Phases 3 and 4 – south to Hanover Square Phase 3, which has no funding commitments, would extend the line southward along Second Avenue from 63rd Street to Houston Street. Upon its completion, a new service will operate running between 125th and Houston Streets. Phases 2 and 3 may cost up to a combined total of $14.2 billion. Phase 4, which also has no funding commitments, The Hanover Square station will be deep enough to allow for the potential extension of Second Avenue Subway service to Brooklyn through a new tunnel under the East River. ==Design and cost==