When a new subway station opened at New York City’s Hudson Yards, it marked the culmination of more than a decade of work by WSP USA in planning a new neighborhood and bringing rail transit to midtown Manhattan’s far west side.
The firm is continuing its contributions to the development of Hudson Yards through its structural engineering for several high-rise buildings on the 28-acre site, as well as work in designing an extension of a new park and boulevard in the area.
The new station, at 34th Street and 11th Avenue, serves the city’s No. 7 line subway, which was extended 1.5 miles from its previous terminus at Times Square (8th Avenue at 42nd Street).
Mayor Bill de Blasio presided at a Sept. 13 opening ceremony, along with Thomas F. Prendergast, chairman of the Metropolitan Transportation Authority (MTA) and other dignitaries. The City of New York funded the $2.4 billion extension of the line; the project was managed by MTA Capital Construction.
WSP led conceptual, preliminary and final design for the subway extension, assisted the MTA in development an overall construction program and contract packaging arrangements, provided construction support services, and—as a consultant to the contractor—served as systems integrator, responsible for ensuring that mechanical-electrical-plumbing (MEP) systems perform as designed.
“The opening of the new station, and our ongoing role at Hudson Yards, is a powerful demonstration of the comprehensive transportation planning and design and structural engineering expertise that enables WSP to contribute to the kinds of diversified building initiatives that will define urban areas in the future,” said Greg Kelly, president and CEO of WSP U.S., who also served as principal-in-charge on the No. 7 line extension project.
The firm prepared a 6,600-page environmental impact statement that considered not only the extension of the subway line, but also the expansion and modernization of the Jacob K. Javits Convention Center and the rezoning of much of the west midtown area of Manhattan for commercial, residential and recreational development expected to total $20 billion. The EIS, completed in 2004 on behalf of the MTA and the city planning commission, has been called the most complex document of its kind in New York history.
“The EIS laid the groundwork for the stunning amount of development now taking place at Hudson Yards,” said Kelly, who added that the firm’s buildings practice is currently performing structural engineering and MEP engineering for 55 Hudson Yards, a 51-story office tower; 3 Hudson Boulevard, a mixed-use 66-story tower; and structural engineering for 15 Hudson Yards, a 70-story residential high-rise.
The 34th Street station, the first new station in 25 years and the 469th in the system, is deep by New York City subway standards—125 feet underground—and is reached by escalators and inclined elevators. Most New York City subway stations are relatively shallow and easily reached by stairways, in accordance with William Barclay Parsons’s plan for the subway system he designed in the 1890s.
“More than 110 years after the subway designed by Parsons opened, it’s gratifying to be such an integral part of the latest extension of the system, as well as other extensions of New York City’s rail transit network,” said Neil Lucey, WSP’s project director.
The firm is providing construction management services for the new Second Avenue Subway, and serves as the lead of a general engineering consultant joint venture for the East Side Access project, which will extend the Long Island Rail Road from Queens to Grand Central Terminal in Manhattan.
The extension of the No. 7 subway line runs from the previous terminus at Times Square, west under West 41st Street, and south under 11th Avenue to West 34th Street, although tail tunnels for train storage extend to West 25th Street. As part of the design process, more than a half-dozen other alignments were studied before the route under 11th Avenue was selected, according to Peter Wahl, who served as WSP’s project manager from 2007 to 2011.
Designing the project posed a number of challenges, including:
The need to avoid the existing tunnels, buildings and other infrastructure required relatively deep tunnels—about 100 feet deep in most places. The tunnels were excavated by two tunnel boring machines (TBMs). As the TBMs dug the tunnels, a cavern for the station was mined through the drill-and-blast method.
Excavation for the tunnels began in May 2009 and was completed by June 2010. The TBMs were lowered into a shaft at the southern end of the tail tunnel and removed from a shaft near the Port Authority Bus Terminal in August 2010, once excavation was complete.
Virtually all construction activity was underground and not visible to the public. Not even riders of the No. 7 line who disembarked at the former terminus of the line at Times Square (42nd Street) were aware of the work to connect the new tunnel to Times Square station, according to Erdem Dogan, who succeeded Wahl as WSP’s project manager.
Extending the No. 7 subway tunnel from the Times Square station required the construction of a tunnel below the Port Authority Bus Terminal, between 8th and 9th avenues. This work, too, was largely invisible to the public, as it was constructed through what Dogan calls “cover-and-cut” tunneling. In this method, Dogan explained, the area was first decked over so that the tunnel could be constructed with minimal impact on the bus operations above.
Wahl said the tunneling excavation generally proceeded very smoothly, even with the challenge of tunneling through an area of poor ground conditions between West 26th and West 28th streets, identified during the conceptual design phase of the project. Tunneling in the area was facilitated by a “ground freezing” operation in which chilled brine was injected into the soil to create a stable mass of earth suitable for excavation by a TBM.
Wahl and Dogan attended the opening ceremony, representing the WSP project team, which at times numbered more than 100 people.
Dogan mused that if the No. 7 line is extended to the New Jersey Transit rail station at Secaucus—as has been publicly proposed by local officials— it might offer WSP an opportunity to continue its 124-year history with New York City’s transit system.
Whether the No. 7 line will ever be extended remains to be seen, but in the meantime WSP will be busy managing the construction of New York’s Second Avenue Subway and contributing to the ongoing development of Hudson Yards.