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Tuesday, December 22, 2009

First phase of Number 7 subway extension completed

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New York City Mayor Michael R. Bloomberg, Deputy Mayor for Economic Development Robert C. Lieber and Metropolitan Transportation Authority Chairman and CEO Jay H. Walder lauded the completion of the first phase of the Number 7 subway extension at the Hudson Yards in Manhattan. The second of two tunnel boring machines has reached the southern wall of the 34th Street Station cavern after mining a combined 2,900 feet from their starting point at 26th Street under 11th Avenue. The $2.1-billion project, funded by the City and managed by the MTA, will help transform the Hudson Yards vicinity into a vibrant 24-hour neighborhood, containing a mix of commercial, residential, retail, open space and recreational uses.

In January of 2005, the City Council approved the Bloomberg Administration's plan for re-zoning the Hudson Yards area, including the Eastern Rail Yards. The City Council will vote on the plan for the Western Rail Yards, which would complete the public approvals process for the development of the area.

"It's been a half century since City government expanded its subway system, but that drought will soon be at an end," said Mayor Bloomberg. "Too often, government falls victim to the temptation to abandon long-term infrastructure projects amidst short-term downturns, and that's why big things never get done. The redevelopment of the Hudson Yards has been talked about for decades, but with the expansion of the number 7 line, its potential will finally be realized."

The tunnel-boring machines were launched last summer from the underground assembly chamber located at 26th Street. The first 300 feet of tunneling was complicated by a section of soft ground between 27th and 28th Streets that required a technique called "ground freeze" to reinforce the ground, allowing the machines to pass through as if it were solid rock. As the tunnel boring machines mine, they place pre-cast concrete lining rings along the excavated tunnel, making up the permanent liner of the finished tunnel. While the new service will terminate at the new 34th Street station, the tunnels continue to 25th Street to allow for the storage of trains.

One tunnel-boring machine has already started mining north of the station cavern toward 42nd Street while the other is being pulled through the cavern and will begin mining in a few weeks. Tunneling north from 34th Street also presents unique challenges, as track will run under the 8th Avenue Subway, Amtrak/NJ TRANSIT tunnels, tunnels to the former New York Central Line, the Lincoln Tunnel and the Port Authority Bus Terminal and ramps. Excavation and underpinning of the 8th Avenue Subway line is underway to allow the new tunnels to tie into the existing 7 Line tail tracks at Times Square.

Tunneling will be completed in the spring of 2010, when work will commence on station entrances and finishes, as well as support facilities such as ventilation and traction power substations. The new service will open in December in 2013 as scheduled.

Construction of the tunnels and the 34th Street Station cavern is being done by S3II Tunnel Constructors, a joint venture of J.F. Shea Construction, Inc., SKANSKA USA Civil Northeast, Inc., and Schiavone Construction Co., Inc.

The 7 Line Extension will introduce subway service to an emerging mixed-use community in Midtown West, fostering transit oriented development in one of Manhattan's most underserved and underdeveloped areas. The City created two local development corporations, the Hudson Yards Infrastructure Corporation, which is contributing $2.1 billion to the project, and the Hudson Yards Development Corporation, which oversees planning and development in the Hudson Yards on behalf of the City.

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