As part of the New York City’s redevelopment of the far west side of the mid-town Manhattan, the No. 7 Subway Line Extension project will add 1.5 miles of twin bored tunnels to the existing subway line and two new subway stations. The underground construction has two major components: (1) Running Tunnel & 34th Street Station Cavern, and (2) Tenth Avenue Station & Times Square Connection. The running tunnel contract will have a TBM launching shaft (Shaft A), an Adit connecting Shaft A to the running tunnels, and TBM Assembly Chamber at the southern end of the project, i.e., near 25th Street at Eleventh Avenue, where tunnel excavation begins. This paper will discuss challenges of the design and construction of Shaft A where it meets the Adit.
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