• Corporate HQ, NY
  • Melville, NY
  • Iselin, NJ
  • Ossining, NY
  • Mount Laurel, NJ

No. 7 Subway Line Extension

New York City<br style='line-height:2px'>MTA Capital Construction Company

The No. 7 Subway Line (the Flushing Line) is one of New York City Transit’s busiest, linking the borough of Queens to Midtown Manhattan. The $2.4 billion, 1.5-mile extension brings the No. 7 Line to 34th Street and 11th Avenue, the heart of what will be Manhattan’s newest neighborhood—Hudson Yards. The No. 7 Subway Line extension is a vital element of the new development taking place in this area. The extension also improves service reliability for riders of the line in Queens and Manhattan by providing additional storage space for trains and provides convenient access to the Jacob Javits Convention Center.

HAKS provided construction inspection services for the extension, including TBM alignment verification, as part of the construction management team for MTA Capital Construction. The new twin-tube tunnel runs from 11th Avenue and 25th Street in a northerly direction with a radius into 41st Street and connection to the existing No. 7 line at Times Square and a new terminal station at 34th Street.  The project also includes ventilation buildings at four sites along the running tunnels—25th Street and 11th Avenue, 34th Street and 11th Avenue, 35th Street and 11th Avenue and 41st Street and Dyer Avenue. Six cross-passages connect the tunnels.

The extension comprises 9,432 feet of tunnel to accommodate a two-track railroad with two lay-up tracks for storage. The project includes two 21.5-foot-exterior-diameter bored tunnels and the new terminal station at 34th Street. Excavation of rock was by both drill and blast and TBM. The underground cavern was excavated by drill and blast, and a new power substation specified for the TBMs was constructed.

The project used the first double-shielded TBM to tunnel under New York City while placing precast concrete segments to form the tunnel walls. For the first time in New York City, a ground freezing method was used to harden soil to act as rock, thereby enabling the TBMs to maintain proper course while boring and placing the tunnel liners.

Construction took place beneath busy city streets and in proximity to existing structures and, in some cases, other major transit lines.

The extension opened on September 13, 2015.