No. 7 Subway Line Extension

Location New York, NY

Client New York Metropolitan Transportation Authority (MTA)

Services Construction Management

Project Value $2.1 billion

The MTA’s No. 7 Line Subway Extension project provides transit access to the West Side of Manhattan, NY, including the Jacob Javits Convention Center, by extending the 7 Line westward from Times Square under West 41st Street and southward along 11th Avenue to the southerly terminus at West 25th Street. The extension provides approximately 12,400 LF of tunnel to accommodate a 2-track railroad with 2 lay-up tracks for storage of 3 trains each. The extension also provides a two-track terminal station on 11th Avenue at West 34th Street. The extension is transforming the Hudson Yards into a vibrant 24-hour neighborhood containing a mix of commercial, residential, retail, and recreational uses while enhancing the vitality of New York City as a whole.

The scope of work included 2, 22.5 foot diameter bored tunnels and a station structure (34th Street Station) approximately 66 feet by 960 feet, extending about 110 feet below ground level. Tunneling work was performed using Double Shielded TBM at a maximum depth of 125 feet underground. The station cavern was constructed in rock using the drill and blast method. Ultimately, more than 400,000 CY of rock was excavated. The new extension includes six cross passages to connect the two running tunnels and underpinning and structural modifications of the existing Port Authority Bus Terminus at 8th Avenue. The project also involved approximately 215,000 CY of cast-in-place concrete for underground concrete structures, along with associated logistics, waterproofing, and quality assurance/control required for their placement. 

The Hill/LiRo/HDR joint venture was responsible for providing construction management services during all tunneling work and during construction of all facilities and infrastructure. This included ventilation buildings, track, and rail systems and stations. We also provided project controls services throughout the project using an earned value management system (EVMS) integrated with Primavera resource/cost-loaded schedule software. This helped to closely monitor the program schedule and budget, while Constructware document controls software helped to organize the program documents.  

The project won numerous awards, including an Award of Merit from ENR New York, a Project Achievement Award – Program Management/Program Phase -Infrastructure from CMAA, and Construction Project of the Year from the New York State Society of Professional Engineers.

In the 50-year history of billion-dollar projects for the MTA, the tunnels phase of this project was the first to be both under budget and ahead of schedule, and the overall project achieved revenue service under budget. In addition, the project received the Construction Project of the Year award from the New York State Society of Professional Engineers for outstanding professional engineering efforts in developing creative solutions and innovative technologies in construction of an infrastructure project.