Proposed expansion of the New York City Subway

Since the opening of the original New York City Subway line in 1904, and throughout the subway's history, various official and planning agencies have proposed numerous extensions to the subway system. The first major expansion of the subway system was the Dual Contracts, a set of agreements between the City of New York and the IRT and the BRT. The system was expanded into the outer reaches of the Bronx, Brooklyn, and Queens, and it provided for the construction of important lines in Manhattan. This one expansion of the system provided for a majority of today's system.
Even with this expansion, there was a pressing need for growth. In 1922, Mayor John Hylan put out his plan for over 100 miles of new subway lines going to all five boroughs. His plan was intended to directly compete with the two private subway operators, the IRT and the BMT. This plan was never furthered. The next big plan, and arguably the most ambitious in the subway system's history, was the "Second System". The 1929 plan by the Independent Subway to construct new subway lines, the Second System would take over existing subway lines and railroad rights-of-way. This plan would have expanded service throughout the city with 100 miles of subway lines. A major component of the plan was the construction of the Second Avenue Subway. The Stock Market Crash of 1929 put a halt to the plan, however, and subway expansion was limited to lines already under construction by the IND.
During the 1930s and 1940s, the plans were revised, with new plans such as a line to Staten Island and a revised line to the Rockaways. In the late 1940s and 1950s, a Queens Bypass line via the Long Island Rail Road's Main Line was first proposed as a branch of the still-planned Second Avenue Subway. In addition, capacity on existing lines became improved through the construction of strategic connections such as the Culver Ramp, the 60th Street Tunnel Connection, and the Chrystie Street Connection, and through the rebuilding of DeKalb Avenue Junction. These improvements were the only things to come out of these plans. Eventually, these plans were modified to what became the Program for Action, which was put forth by the New York City Transit Authority in 1968. This was the last plan for a major expansion of the subway system. The plan included the construction of the Second Avenue Subway, a Queens Bypass line, a line replacing the Third Avenue El in the Bronx, and other extensions in the Bronx, Queens, and Brooklyn. While ambitious, very little of the plan was completed, mostly because of the financial crisis in the 1970s.
Until the 1990s, there was little focus on expansion of the system because the system was in a state of disrepair, and funds were allocated to maintaining the existing system. In the 1990s, however, with the system in better shape, the construction of the Second Avenue Subway was looked into again. Construction of the Second Avenue Subway started in 2007, and the first phase was completed in 2017. Since the 1990s, public officials and organizations such as the Regional Plan Association have pushed for the further expansion of the system. Projects such as the TriboroRx, a circumferential line connecting the outer boroughs, the reuse of the Rockaway Beach Branch, and the further expansion of the Second Avenue Subway have all been proposed, albeit mostly unfunded.
The Triborough System was a proclamation for new subway lines to the Bronx and Brooklyn. The new lines include the IRT Lexington Avenue Line, IRT Pelham Line, and IRT Jerome Avenue Line. The Manhattan Bridge line described below later became the BMT West End Line, BMT Fourth Avenue Line, the BMT Sea Beach Line, and the Nassau Street loops.
In 1911, William Gibbs McAdoo, who operated a competing subway company called the Hudson & Manhattan Railroad, proposed building a line under Broadway between Hudson Terminal and Herald Square. He later proposed that the Broadway line be tied into the IRT's original subway line in Lower Manhattan. The Broadway line, going southbound, would merge with the local tracks of the IRT Lexington Avenue Line in the southbound direction at 10th Street. A spur off the Lexington Avenue Line in Lower Manhattan, in the back of Trinity Church, would split eastward under Wall Street, cross the East River to Brooklyn, then head down the Fourth Avenue Line in Brooklyn, with another spur underneath Lafayette Avenue.
The Triborough System later became part of the Dual Contracts, signed on March 19, 1913 and also known as the Dual Subway System. These were contracts for the construction and/or rehabilitation and operation of rapid transit lines in New York City. The contracts were "dual", in that they were signed between the City and the IRT and Municipal Railway Company, a subsidiary of the BRT (later BMT).
Some lines proposed under the Contracts were not built, most notably an IRT line to Marine Park, Brooklyn (at what is now Kings Plaza) under either Utica Avenue, using a brand-new line, or Nostrand Avenue and Flatbush Avenue, using the then-new IRT Nostrand Avenue Line. There were also alternate plans for the Nostrand Avenue Line to continue down Nostrand Avenue to Sheepshead Bay.
On August 28, 1922, Mayor John Francis Hylan unveiled his own plans for the subway system, which was relatively small at the time. His plan included building over 100 miles (160 km) of new lines and taking over nearly 100 miles (160 km) of existing lines. By the end of 1925, all of these routes were to have been completed. The lines were designed to compete with the IRT and BMT.
Hylan's plan contained the following lines:
Only some of Hylan's planned lines were built to completion. Completed lines included:
Major Phillip Mathews disagreed with the Board of Transportation's plan, and in response, he published a report, on December 24, 1926, titled "Proposed Subway Plan for Subway Relief and Expansion". He said that that congestion would not be addressed for Brooklyn and the Bronx; only the planned Grand Concourse line would alleviate congestion, in this case congestion on the IRT Jerome Avenue Line. There would be little relief on the two lines jointly-operated between the IRT and the BMT. He came up with his own plan. He proposed that the Eighth Avenue Line, through a connection from Fulton or Wall Streets to Chambers Street, be connected to the BMT's lines to Coney Island, with a possible connection at the Manhattan Bridge's south side.
In Manhattan, he proposed a new four-track line running down Third Avenue from City Hall, with connections to the White Plains Road and Pelham Lines in the Bronx. The line would therefore have to be built to IRT clearances. At the line's southern end, a connection would be built to the Eastern Parkway Line near Franklin Avenue via a new set of tubes under the East River. To alleviate congestion on the Queens lines, a new trunk line would run from Eighth Avenue in Manhattan to Jamaica, with transfers to the north–south lines in Manhattan and to Brooklyn Crosstown service. This would later be built as the IND Queens Boulevard Line.
To round out expansion in Manhattan, he proposed that an extension of the BMT Canarsie Line to Eighth Avenue. This was built at a later date. To connect the outer boroughs, a four-track Brooklyn-Queens crosstown line would be designed, with the possibility for future extensions into the Bronx and Staten Island.
In 1926, a loop subway service was planned to be built to New Jersey. The rationale given was:
Because it would be utilized in both directions, the capacity of the proposed interstate loop line would be equivalent, it is said, to two 2-track lines or one 4-track line from New Jersey to New York City due to its having two crossings between New Jersey and New York. The loop was said to be able to carry 192,500 passengers per hour, or 4.62 million daily passengers, had it been built. The estimate was based on the operation of 35 trains per hour in each direction, and each train would be eleven cars long and would carry 100 passengers per car. It was to be built as a multi-phase project, wherein the IRT and BMT would work together to build that system to New Jersey. Extensions of the IRT Flushing Line and BMT Canarsie Line were both considered; the Canarsie Line was to be extended to Hoboken near the Palisades, while the Flushing Line was to be extended to Franklin Street between Boulevard and Bergenline Avenues in Union City. Ultimately, the cost was too great, and with the Great Depression, these ideas were quickly shot down.
In 1954, Regional Plan Association advocated for an extension of the BMT Canarsie Line from Eighth Avenue to Jersey City under the Hudson River. The tunnel under the Hudson would have cost $40 million. The extension would have provided access to commuter railroads in New Jersey as most lines converged there, and the lines that didn't would be rerouted to stop there. The RPA also suggested having a parking lot there for access from the Pulaski Skyway and the New Jersey Turnpike. It was suggested that either the New York City Transit Authority, the Port Authority of New York and New Jersey or the Bi-State Metropolitan Rapid Transit Commission would do the construction.
In 1963, three major commuter groups in New Jersey made expansion proposals. One of them would have involved an extension of the IRT Flushing Line under the Hudson River with a three-track tunnel and then connect with the New York, Susquehanna and Western Railroad.
In 1986, the Regional Plan Association suggested extending the IRT Flushing Line to New Jersey's Meadowlands Sports Complex.
On November 16, 2010, the plan was revisited yet again, as The New York Times reported that Mayor Michael Bloomberg's administration had been working on a plan to extend the 7 service across the Hudson River to Hoboken and continue to Secaucus Junction in New Jersey, where it would connect with most New Jersey Transit commuter lines. It would offer New Jersey commuters a direct route to Grand Central Terminal on the East Side of Manhattan and connections to most other New York City subway routes. This was being planned as an extension of the already-under construction 7 Subway Extension (see below).
In April 2012, citing budget considerations, the director of the MTA, Joe Lhota, said that it was doubtful the extension would be built in the foreseeable future, suggesting that the Gateway Project was a much more likely solution to congestion at Hudson River crossings. A feasibility study commissioned by the city and released in April 2013 revived hope for the project, however, with Mayor Bloomberg saying "Extending the 7 train to Secaucus is a promising potential solution ... and is deserving of serious consideration."
In 2017, a further extension of the 7 train to New Jersey was suggested once again, this time as an alternative to constructing a replacement for the Port Authority Bus Terminal. An alternative would include a new terminal at Secaucus Junction in conjunction with the 7 extension. In February 2018, it was revealed that the Port Authority of New York and New Jersey had advertised for consultants to write a feasibility study for such an extension, and that it had received bids from several companies. This extension was being planned along with the Gateway Project and, if built, would be able to accommodate a projected 38% increase in the number of people commuting between the two states. The 18-month study would include input from the Port Authority, the MTA, and NJ Transit. If the New Jersey subway extension were to be constructed, it could complement the Gateway Project, which might become overcrowded by 2040.
Before unification in 1940, the government of New York City made plans for expanding the subway system, under a plan referred to in contemporary newspaper articles as the IND Second System (due to the fact that most of the expansion was to include new IND lines, as opposed to BMT/IRT lines). The first one, conceived in 1929, was to be part of the city-operated Independent Subway System (IND). By 1939, with unification planned, all three systems were included. Very few of these far-reaching lines were built, though provisions were made for future expansion on lines that intersect the proposals.
The core Manhattan lines of the expansion were the Second Avenue Line (with an extension into the Bronx) and the Worth Street Line, connecting to the Rockaways. The Rockaways were eventually served by the subway via a city takeover of the Long Island Rail Road's Rockaway Beach Branch. A segment of the proposed Second Avenue Subway opened for passenger service in January 2017. The majority of the proposed lines were to be built as elevated subways, likely a cost-cutting measure. The majority of the expansion was to occur in Queens, with the original proposal suggesting 52 miles (84 km) of track be built in Queens alone.
The first plan was made on September 15, 1929 (before the IND even opened), and is detailed in the table below. Cost is only for construction, and does not include land acquisition or other items.
The IND expansion plan was revised in 1932. It differs from the 1929 plan, but there are 60.93 route‑miles (98.06 km), of which 12.49 miles (20.10 km) are in Manhattan, 12.09 miles (19.46 km) in the Bronx, 13.14 miles (21.15 km) in Brooklyn, and 23.21 miles (37.35 km) in Queens. It would include a new 34th Street crosstown line, a Second Avenue Subway line, a connection to the New York, Westchester and Boston Railway, and extensions of the IRT Nostrand Avenue Line, IRT Flushing Line, and BMT Astoria Line. It would have created a subway loop bounded by 2nd and 10th Avenues, and 34th and 125th Streets. This plan included no extensions to Whitestone, Queens, however, with the plan to instead serve more densely populated areas such as Astoria and the Roosevelt Avenue corridor.
The plan would also take over the local tracks of the New York, Westchester and Boston Railway, and the Rockaway Beach Branch of the Long Island Rail Road.
The table of route miles is as follows:
Other plans, proposed during the same time as the IND Second System plans, included the following:
An earlier plan in 1920 had an even more expansive plan, with several dozen subway lines going across all five boroughs.
The following provisions were made for connections and transfers to the new lines. It is of note that only four of these provisions were completed.
The South Fourth Street shell, if complete, was supposed to handle service as follows:
Another plan for the South Fourth Street shell was simpler (and was the plan that was partially completed):
The Utica Avenue station shell, if complete, would be in the standard local-express-express-local platform configuration.
The Jackson Heights–Roosevelt Avenue shell, a two-trackbed island-platformed station, would have been for local trains terminating at the station. Express trains would have stopped at the lower level (IND Queens Boulevard Line) platforms.
After World War II and up until the late 1990s, the New York City Subway did not expand much. Only 28 stations opened in that time, compared to the remaining 393 stations, which opened from the 1880s to before World War II. As such, there have been many plans to expand the system during this time period.
The New York City Board of Transportation revised its plans for subway expansion, and released them in 1938 and 1940.
The IND Concourse Line got funding to be extended eastward past 205th Street, but Bronx residents wanted to rehabilitate the New York, Westchester and Boston Railway right-of way. This funding was reallocated, and the old NYW&B line became the IRT Dyre Avenue Line in December 1941, and the IND Concourse Line extension was not brought up again until 1968.
In 1942, Mayor Benjamin F. Barnes of Yonkers proposed that the Getty Square Branch of the New York Central's Putnam Division be acquired for an extension of the IRT Broadway–Seventh Avenue Line from Van Cortlandt Park. This service would replace the service operated by the New York Central, which was slated to be discontinued by the New York Central.
A rail link to LaGuardia Airport was proposed in 1943, when the city Board of Transportation proposed an extension of the BMT Astoria Line (currently served by the N and ​W trains) from its terminus at Ditmars Boulevard. The line would have run along Ditmars Boulevard, and would have cost $10.5 million.
In 1946, the Board of Transportation issued a $1 billion plan that would extend the subway to the farthest reaches of the outer boroughs.
Even though the Board of Transportation did not approve these ideas, they were still proposed.
In 1949, the Board of Transportation issued a $504 million plan to increase capacity on several subway lines through the construction of a new trunk line under Second Avenue.
On June 21, 1950, a plan was created by the Board of Transportation and sent to Mayor O'Dwyer concerning rapid transit expansions in Queens. The total cost of the plan would have been $134.5 million. Many things were planned:
On September 13, 1951, the Board of Estimate approved a plan put forth by the New York Board of Transportation that would cost $500 million. Many things were planned:
The Board of Estimate requested that the Board of Transportation evaluate a spur of the IRT Pelham Line to Throggs Neck in the Bronx.
The Board of Estimate accepted the following items into its 1954 budget from the New York City Transit Authority:
In March 1954, the Transit Authority issued a $658 million construction program including the following projects:
In 1954, Regional Plan Association advocated for an extension of the BMT Canarsie Line from Eighth Avenue to Jersey City under the Hudson River. The tunnel under the Hudson would have cost $40 million. The extension would have provided access to commuter railroads in New Jersey as most lines converged there, and the lines that didn't would be rerouted to stop there. The RPA also suggested having a parking lot there for access from the Pulaski Skyway and the New Jersey Turnpike. It was suggested that either the New York City Transit Authority, the Port Authority of New York and New Jersey or the Bi-State Metropolitan Rapid Transit Commission would do the construction.
John T. Clancy, a Democratic incumbent running for Queens Borough President in 1961 proposed third tracking the BMT Jamaica Elevated Line to provide express service, and reactivating the Rockaway Beach Branch from Rego Park to Liberty Avenue.
In July 1962, the NYCTA announced that it had asked the city for money to build a $190 million high-speed, non-stop subway line from Midtown to the Bronx. The line would have only operated during rush hours. It was estimated that if the funds were given to the project, it would be completed in 1970. The line would be a two-track line running from 59th Street between Fifth and Seventh Avenues to the Bronx, running under Central Park. Running non-stop for 6.5 miles, it would have been the longest continuous run in the subway system. The line, on its southern end, would connect to the BMT Broadway Line at Seventh Avenue near 59th Street and to the IND Sixth Avenue Line near 58th Street and Sixth Avenue.
The line would then run through a deep tunnel under Central Park until 110th Street. There would be provisions for a future crosstown line under 76th Street to Queens. The line would then turn east and run along Madison Avenue to 138th Street. One branch would connect to the express track of the IRT Pelham Line, which would be converted to accommodate larger B Division trains. In the morning rush hour, trains from Pelham Park would only make express stops. A new stop would be built at 138th Street and Grand Concourse where transfers would have been available to the IRT White Plains Road and IRT Jerome Avenue Line trains.
The second branch would continue under the Grand Concourse until 161st Street where it would connect to the IND Concourse Line at 161st Street. This connection would allow for the diversion of Concourse Line express trains onto the new line, allowing for the addition of an equal number of trains to the IND Central Park West express service and provide relief to that line. The construction of this line was viewed as necessary to relieve the IRT Lexington Avenue Line.
In February 1963, the New York City Transit Authority issued a preliminary proposal for rapid transit expansion in the borough of Queens. The plan was designed to relieve congestion on the IRT Flushing Line and IND Queens Boulevard, to deal with expected population growth, and to provide service to areas of the borough without transit service. To expand service to other areas of the borough a new trunk line would be built to provide the necessary capacity. The planned extensions were expected to relieve crowding on the IRT Flushing Line by 22 percent and on the IND Queens Boulevard Line by 19 percent.
The first phase of the transit expansion would build a trunk line connecting the IND Queens Boulevard Line's local tracks at Steinway Street and Broadway using existing provisions with the IND Sixth Avenue Line and BMT Broadway Line in Manhattan. The new line would have run under 34th Avenue, a new tunnel under the East River, and 76th Street before turning south under Central Park. Connections would be made to the IND Sixth Avenue Line at 58th Street and to the BMT Broadway Line's stub tracks at 59th Street and Seventh Avenue. In Manhattan, there would have been a transfer connection to the 77th Street station on the IRT Lexington Avenue Line and a station in Central Park at 70th Street.
Provisions would be built for a planned extension to the Bronx. At Steinway Street, switches would be constructed to all GG trains from Brooklyn to terminate there. The new 4.5 miles (7.2 km) line would have provided an additional 30 trains per hour between Queens and Manhattan with a future northern extension. Initially, the line would be used for 15 trains per hour running to the IND Sixth Avenue Line from the IND Queens Boulevard Line. The construction of the trunk line was expected to cost $138.6 million, of which $37.4 million would be spent for the section south of 76th Street. The earliest possible date for the completion of the line would have been 1970.
To provide service to unserved areas of Queens, three additional routes were considered. The first route would have served northern and northeastern Queens, running along 34th Avenue, Northern Bouelvard, Main Street, Kissena Boulevard, Parsons Boulevard, and one of the Horace Harding Expressway service roads to Springfield Boulevard. The 10.3 miles (16.6 km)-line would have consisted of two tracks and would have cost $219.4 million. The second route would be a branch of the IND Fulton Street Line heading under Linden Boulevard and Merrick Boulevard to Springield Boulevard.
Two options were considered for this line. The first option would have branched off of the Fulton Street Line near Pitkin Avenue and Euclid Avenue using existing provisions in the tunnel. The second option would have extended the Liberty Avenue Elevated from Lefferts Boulevard. This option would have required the acquisition of private property to widen Liberty Avenue so that the line could transition from an elevated line to a subway line and to make the turn from Liberty Avenue and Linden Boulevard. The subway option would have been 6.6 miles (10.6 km) long and would have cost $116 million while the elevated/subway option would have been 4.5 miles (7.2 km) and would have cost $80.8 million.
The third route would have connected the IND Rockaway Line to the IND Queens Boulevard Line using the Rockaway Beach Branch and an existing provision in the tunnel east of 63rd Drive. The Rockaway Beach Line had been abandoned by the Long Island Rail Road on June 8, 1962. A new stop would be built at Linden Boulevard to connect with a new subway line. This line was expected to cost $39.9 million.
In addition to expanding service to Queens, service to the Bronx would have been expanded as well. The new trunk line connecting the BMT Broadway Line and IND Sixth Avenue Line to Queens south of 76th Street would have been used for the new line to the Bronx. This line would have run under the center of Central Park and then running via Fifth Avenue once out of the park at 110th Street, and would continue under the East River with a branch connecting to the IRT Pelham Line, which would have been modified in order to fit B Division subway cars, and a branch continuing up the Grand Concourse and then connecting to the IND Concourse Line.
In May 1963, the New York City Planning Commission proposed the following in response to the NYCTA's proposal:
Similar plans were made by the New York City Transit Authority in 1968. They included:
The Archer Avenue Lines are two lines, split between the BMT and IND, mostly running under Archer Avenue in the Jamaica neighborhood of Queens. Conceived as part of these 1968 expansion plans, they opened on December 11, 1988. There are stub-end tunnels east of the line's northern terminus, Jamaica Center–Parsons/Archer, on both levels, which extend past the station for possible future extensions.
The 63rd Street Lines are two lines also split between the BMT and IND. The short BMT line connects the express tracks of the BMT Broadway Line from 57th Street–Seventh Avenue to Lexington Avenue–63rd Street, where it now runs through to the Second Avenue subway. The IND line runs from the IND Sixth Avenue Line at 57th Street in Manhattan east under 63rd Street and the East River through the 63rd Street Tunnel to the IND Queens Boulevard Line in Queens. There is a stub-end tunnel at the northern terminus of the IND line that is intended for the Queens super-express bypass.
In Lower Manhattan, plans were made for the following:
In 1986, the Regional Plan Association suggested extending the IRT Flushing Line across the Hudson River to the Meadowlands Sports Complex in East Rutherford, New Jersey.
In 1986, the MTA issued a study on expanding transit options on the west side of Manhattan. It was proposed to use the West Side Line viaduct (today's High Line), and various means of transportation were proposed, including monorail, passenger rail trains, or subway trains. It also proposed to extend the IRT Flushing or BMT Canarsie Lines (7 and <7>​ and L, respectively).
In 1990, the MTA proposed a rail line connecting LaGuardia Airport and John F. Kennedy International Airport. The line would have operated over the Grand Central Parkway and the Van Wyck Expressway. There would be stations at Shea Stadium and Jamaica. The system was proposed to cost $2 billion. The MTA estimated that the rail link would take 30 minutes from Kennedy to LaGuardia, and the frequency of service would initially be every 15 minutes. There would be a two-track alignment with one track for each direction, as well as at least two trains heading in each direction at all times. If the link were built, the average travel time from Manhattan to Kennedy would have been about 45 minutes using the Long Island Rail Road, including transfers. To LaGuardia, the average travel time from the Grand Central station using the IRT Flushing Line would be 47 minutes.
In 1998, an extension of the BMT Astoria Line to LaGuardia Airport was planned, but the plan was canceled in 2003 following community opposition.
In 1999, the Regional Plan Association considered a full-length Second Avenue Subway from Broad Street to 125th Street, along with the LIRR East Side Access. It also planned the following extensions:
The new set of extensions proposed by the RPA, dubbed "MetroLink", would make use of existing commuter rail infrastructure, so as to make it interoperable with the New York City Subway. Nine hundred fifty "Rx" hybrid railcars would be ordered, with yard expansions and new yards being built. MetroLink, consisting of 31 new metro stations (not counting three recycled commuter rail stations) and 19 new route‑miles of track (31 km) (not including existing commuter rail and then-under construction AirTrain JFK route miles) would have reduced the load on the IRT Lexington Avenue Line, the IRT Broadway–Seventh Avenue Line, and the IND Queens Boulevard Line. Two of these stations would be in Brooklyn, three in Queens, nine in the Bronx, and twenty in Manhattan. Five services would be run:
Stations would have been located at:
The AirTrain JFK, Atlantic Branch, Main Line ROW, and Northeast Corridor would all be "recycled" to accommodate subway service under this plan. The Nostrand Avenue and East New York LIRR stations would also have been closed under MetroLink.
The New York City Subway has opened five subway stations since 2009, and up to 15 more subway stations are planned. However, the 21st-century expansion plans pale in comparison to some of the subway system's other previous plans.
The 7 Subway Extension was devised in the late 1990s to extend the IRT Flushing Line, which carries the 7 local and <7> express services, further westward into Manhattan. The extension stretches a total of 1 mile (1.6 km) from its former terminus at Times Square to a new western terminus at 34th Street and 11th Avenue. The tunnels are actually 1.5 miles (2.4 km) long. A second station at 10th Avenue–41st Street was dropped from the plans in October 2007, but could be restored if funding can be found. The extension's opening had been delayed to June 2014, with the rest of the 34th Street station to open at the end of 2015.
Michael Horodniceanu, chief of MTA Construction Company, told The New York Times that complications in the installation of the inclined elevator would likely cause a further delay of about three months, bringing the opening date to very late summer or early fall of 2014. Further complications in February 2014 brought the projected date of the opening to November 2014, then to February 2015, then spring 2015, and to summer 2015. The station opened in September 2015.
As proposed under the RPA's Fourth Regional Plan, a second 7 Subway Extension would be built, serving 23rd Street before connecting with the existing 14th Street/Eighth Avenue station.
The Second Avenue Subway was repeatedly delayed and shaved back from a six-track combined local/express line to a two-track superexpress line since 1919 (with occasional construction between 1972 and 1976). Construction of the Second Avenue Subway began in 2007. A tunnelling contract was awarded to the consortium of Schiavone/Shea/Skanska (S3) by the Metropolitan Transportation Authority (MTA) on March 20, 2007. This followed preliminary engineering and a final tunnel design completed by a joint venture between AECOM and Arup. Parsons Brinckerhoff is the Construction Manager of the project. This contract, and the full funding grant agreement with the Federal Transit Administration, which was received in November 2007, is for Phase I of the project, a new line between the existing 63rd Street Line and 96th Street and Second Avenue. The total cost of the 8.5-mile (13.7 km) line is expected to top $17 billion.
A ceremonial ground-breaking for the Second Avenue Subway was held in April 2007. The tunnel boring machine (TBM) began digging the tunnels for Phase I in May 2010 and completed its excavations in September 2011. Phase I, consisting of two miles (3.2 km) of tunnel and three stations, was opened in January 2017. It cost $4.45 billion. A 1.5-mile (2.4 km), $6 billion second phase is in planning; land acquisition for Phase 2 started in April 2022. As of October 2023, Phase 2 was set to open in early 2032.
The RPA's Fourth Regional Plan proposed two northward extensions. Phase 2B would be an extension of Phase 2 under 125th Street from Lexington Avenue to Broadway. Phase 2C would be a spur to Third Avenue–149th Street, connecting with the IND Concourse Line.
A proposal for the LIRR Bay Ridge Branch would have the New York City Subway use the tracks to link Brooklyn, Queens (both already linked by the G train) and the Bronx via the Hell Gate Bridge. Based on Paris's RER commuter rail system, the Triboro RX proposal would create a partial loop around the city. In 1996, the Regional Plan Association conducted a study to determine the feasibility of the rail link. The original proposal would have terminated at Yankee Stadium. The proposed line, discussion of which was revived in 2012, would connect to all non-shuttle subway services at 12 stations.
The line in this proposal would have terminated at Hunts Point. The line was brought back in the 2015 report "The Overlooked Boroughs" by the Regional Plan Association. The line would be 24 miles (39 km) long and would consist of 22 stations, would cost $1 billion and is projected to have more than 100,000 daily riders. Plans for the line date back to 1995.
Obstacles for the proposal include the proposed Cross-Harbor Rail Tunnel, the lack of electrification on the line, as well as the single-tracking in some parts of the line. The current iteration of the plan would have its northern terminus be Co-Op City South using the Hell Gate Branch. The LIRR Bay Ridge Branch and the New York Connecting Railroad have freight operating along them, and are regulated by the Federal Railroad Administration (FRA). FRA rules require a certain distance between freight and passenger trains that share rights-of-way, and as a result it is uncertain whether the right-of-way is wide enough or if more durable train cars are needed to be able to share the same tracks. The RPA's 2015 plan considered having FRA compliant light rail vehicles run over the line. In addition to providing transfer opportunities, the line would provide transit access to areas without it in Glendale and Middle Village in Queens, as well as in Flatlands and Canarsie in Brooklyn.
In mid-October 2019, the MTA announced that it would study the feasibility of restoring passenger service on the Bay Ridge Branch portion of the route. In early January 2022, as part of her State of the State address New York governor Kathy Hochul announced that the state would move forward with the Bay Ridge Branch Line by conducting an environmental study on the Interborough Express (IBX), a 14-mile (23 km) corridor using the existing Bay Ridge Branch and Fremont Secondary from Bay Ridge, Brooklyn, to Jackson Heights, Queens. End-to-end travel times are expected to be less than 40 minutes, and weekday ridership is projected to be 115,000. The route would connect up to 17 subway lines and the Long Island Rail Road. The MTA indicated in September 2022 that it wanted to construct the IBX as a light rail line, and Hochul announced in January 2023 that the project would proceed as a light rail corridor.
The Long Island Rail Road (LIRR) abandoned the Rockaway Beach Branch in 1962; ever since it has been sought after for reactivation for train service. The line has not been reactivated due to local opposition, specifically the homeowners who live along the right-of-way. One group, QueensLink, wants the line to be reactivated between the 63rd Drive–Rego Park station on the IND Queens Boulevard Line to the north and the IND Rockaway Line to the south, providing a north-south connection in Queens. A second group would use the right-of-way as a linear park, known as the Queensway, a proposal inspired by the success of the High Line in Manhattan. A third group consists of homeowners who would have nothing done, keeping the line as is.
Talks of reactivating the line were publicly endorsed in February 2012 by Assemblymen Phillip Goldfeder and Michael G. Miller. Goldfeder commented "The commute for people here is only going to go from bad to worse. You can't talk about a convention center without talking about transportation." Goldfeder and Miller said they are not opposed to turning sections of the line into a park, but said people who live in the Rockaways, Ozone Park and other areas have no quick or easy way to get into Manhattan. The Genting Group, which operates Resorts World casino and have been asked to construct the convention center, are evaluating several plans to increase transportation access. Genting is committed to paying for part of the transportation improvements. Advocates of the Queensway, a proposed public park along the branch's route, are against resumption of rail service, stating that current bus service fills current transportation needs in the area. U.S. Representatives Hakeem Jeffries and Gregory Meeks added their support for the project in March 2013. Both representatives will push to allocate federal transportation subsidies to study a plan for restored passenger service.
The line would cost $1 billion, if built in its full length with a connection to the IND Queens Boulevard Line, and would stretch across 3.5 miles (5.6 km), providing connections to several subway services as well as the LIRR. Another possible option would have Long Island Rail Road service restored with service to seven stations along the right-of-way, with service ending in Howard Beach. The line would serve upwards of 250,000 passengers per day and would provide access to JFK Airport from Midtown Manhattan. In February 2015, the Regional Plan Association suggested having some F trains, after running through the 63rd Street Tunnel, be rerouted to operate over the Lower Montauk Branch of the LIRR running through underserved Maspeth and Glendale and then meeting up with the Rockaway Beach Branch in Rego Park.
The BMT Astoria Line extension to LaGuardia Airport was suggested as part of LaGuardia's long-range expansion/renovation plan. Currently, no New York City Subway routes service the airport directly, but provisions for a subway connection are part of a 2014 long range rebuilding plan by the MTA. The New York Daily News' editorial board came out in support of this extension on February 21, 2017, detailing why this route is superior to Governor Andrew Cuomo’s plan for an AirTrain from LaGuardia to Willets Point.
In April 2015, New York City Mayor Bill de Blasio announced a new plan for building a subway line under Utica Avenue in Brooklyn. Previous plans, most recently the Program for Action, had provisions for such a line. It would branch off from the IRT Eastern Parkway Line (2, ​3, ​4, and ​5 trains) at Crown Heights–Utica Avenue. The new line being proposed is part of de Blasio's "One New York" plan, which aims to improve transit, reduce emissions, and fight poverty. If built, the line would go to Flatbush Avenue, near Kings Plaza. Since the Metropolitan Transportation Authority had budget shortages as of April 2015, however, it is unclear how the line would be funded or built.
The MTA Board allocated $5 million for a feasibility study, the Utica Avenue Subway Extension Study, for this proposal in the MTA's 2015–2019 Capital Program. In August 2016, it was reported that the MTA was looking into an extension of the IRT Nostrand Avenue Line along Flatbush Avenue to Marine Park, which would allow trains to serve Kings Plaza. Both the Utica Avenue and Nostrand Avenue proposals for extensions to Kings Plaza have been proposed since the 1910s. Planning on the Utica Avenue Line stalled because it was no longer viewed as a priority by the MTA. Planning resumed in April 2019 when New York City Transit joined city agencies in launching the Utica Avenue Transit Improvement Study. The study will look into a subway extension, improved bus rapid transit, and a new light rail line. Since the study occurred concurrently with the 2020 redesign of Brooklyn bus routes, the MTA decided to prioritize the Utica Avenue transit study.
In November 2017, the RPA suggested building both lines as part of its fourth plan. The Nostrand Line was envisioned as a three-stop extension to Avenue Z, while the Utica Line was planned as a five-stop spur to Kings Plaza.
The Regional Plan Association (RPA) released its fourth Regional Plan in November 2017, twenty-one years after its previous Regional Plan had been published. The fourth plan included several lists of suggestions on how to improve the city's transit system, of which subway expansion was a major component. Under the RPA's plan, the Second Avenue Subway would be completed to its full length within Manhattan and then extended to the Bronx. The 7 Subway Extension would expand in scope, with the IRT Flushing Line being extended to 14th Street and Eighth Avenue.
Both the Utica Avenue and Nostrand Avenue Lines in Brooklyn would be realized. Queens would see three subway expansions, including two new Queens lines: one along Northern Boulevard to Flushing or College Point and one along Jewel Avenue to Alley Pond Park. A one-stop extension of the Astoria Line would be built to serve western Astoria. Ultimately, the plan included eight extensions with at least 40 stations in total.
In January 2018, Governor Andrew Cuomo ordered the MTA to conduct a study on the feasibility of building a subway station in Red Hook, Brooklyn, in order to redevelop the area. If approved, the station would likely be built as part of an extension of the IRT Broadway–Seventh Avenue Line past South Ferry in Lower Manhattan with a station at Governors Island possible, but unlikely due to cost and benefit.
As of 2022, a potential extension of the BMT Broadway Line to Red Hook (to be served by the W train) is being evaluated as part of the MTA's 2025–2044 20-Year Needs Assessment.
As of 2022, a potential extension of the IRT New Lots Line (to be served by the 3 train) to Spring Creek, Brooklyn, is being evaluated as part of the 2025–2044 20-Year Needs Assessment.
As part of the 2025–2044 20-Year Needs Assessment, the MTA is also evaluating the possibility of extending the Second Avenue Subway westward under 125th Street following the completion of Phase 2. The line might be extended westward to Broadway and 125th Street, connecting with the IRT Broadway–Seventh Avenue Line's 125th Street station; to Broadway and 137th Street, connecting with the IRT Broadway–Seventh Avenue Line's 137th Street–City College station; to Riverside Drive and 137th Street; or to St. Nicholas Avenue and 135th Street, merging with the IND Eighth Avenue Line.
After the PATH's World Trade Center station was destroyed during the September 11 attacks, there was a proposal to connect the PATH and the New York City Subway. Whereas the original World Trade Center station consisted of five north-south balloon loops that sent eastward trains back west to New Jersey, the rebuilt PATH station would have been built in an east–west alignment. The tracks would have extended eastward by 3,000 feet (910 m) to the Brooklyn Bridge-City Hall station on the New York City Subway's IRT Lexington Avenue Line. The benefits of this connection, called PATH-Lex by its supporters, would have consisted of a one-seat ride from Newark and Jersey City through Lower Manhattan, the East Side of Manhattan, and the Bronx. While the Metropolitan Transportation Authority was interested in the plan, the Port Authority of New York and New Jersey dismissed the idea altogether, due to the complexity of connecting the two separate systems.