The new Second Avenue Subway will end at 125th St with a station stop at 2nd Ave and 106th St! (For those of you paying attention, that's exactly one block west of where I will be living in New York!)
But don't hold your breath -- the need for a subway line under Manhattan's Second Avenue was realized shortly after the First World War. In 1919 New York's 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. The Second Avenue Elevated operated above Second Avenue north of the Queensboro Bridge until 1940 and south to downtown until June 13, 1942. The Third Avenue Elevated operated a block to the west until 1955.
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. Massively scaled-down versions of some of Turner's plans were found in proposals for the new city-owned Independent Subway System (IND). 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.
In 1929, the Board of Transportation of the City of New York tentatively approved the expansion, which included a Second Avenue Line with a projected construction cost of $98,900,000, not counting land acquisition. From north to south, the 1929 plan included four tracks from the Harlem River (where it would continue north as a Bronx trunk line with several branches) to 125th Street, six tracks from 125th Street to a link with the IND Sixth Avenue Line at 61st Street, four tracks from 61st Street to Chambers Street, and two tracks from Chambers Street to Pine Street.
Due to the Great Depression, 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. A scaled down proposal including a turnoff at 34th Street and a connection crosstown was postponed in 1931.
Further revision of the plan and more studies followed. By 1939, construction had been postponed indefinitely, and Second Avenue was relegated to "proposed" status. The 1939 plan for subway expansion took the line not only into the Bronx (by now as a single line to Throggs Neck) but also south into Brooklyn, connecting to the stub of the IND Fulton Street Line at Court Street.
The United States' entry into World War II in 1941 halted all but the most urgent public works projects, delaying the Second Avenue Line once again.
Today, the expected construction dates are:
2007-2015: Phase 1 (96th St. to 63rd St.) State Funding In-Place, Federal Funding Approved. A $333 million contract was awarded on March 22, 2007 to three American firms to build the first portion of Phase 1. Construction work began on 2nd Avenue between 91st and 96th Streets on April 23, 2007 (though the ceremonial groundbreaking was held on April 12, 2007). In its 2008 capital improvement budget proposal, the MTA pushed back completion of Phase I from 2014 to 2015.
2014-2017: Phase 2 (125th St. to 96th St.) Engineering ongoing. No funding commitments. As of February 25, 2008, the MTA's unapproved capital improvement budget proposal sought to fund commencement of Phase II.
2015-2018: Phase 3 (63rd St. to Houston St.) Engineering ongoing. No funding commitments.
2017-2020: Phase 4 (Houston St. to Hanover Sqr.) Engineering ongoing. No funding commitments.