TBMs for Gateway Project Nearing Completion

The Gateway Development Commission (GDC) on Aug. 20 announced that manufacturing of the tunnel boring machines (TBMs) that will build the first mile of the new rail tunnel under the Hudson River is nearing completion. The procurement, manufacture, and factory assembly of the first and second TBM is 85% and 73% complete, respectively.

Manufacturing of the first TBM is expected to conclude in the coming weeks, with both TBMs manufactured by November. The TBMs will then be shipped to New Jersey to be reassembled on site. The TBMs are being built by Herrenknecht AG. Tunnel boring will start in 2026.

New York GDC Commissioner and Co-Chair Alicia Glen, New Jersey GDC Commissioner and Co-Chair Balpreet Grewal-Virk, and GDC Amtrak Commissioner and Vice Chair Tony Coscia said, “The start of tunnel boring next year will mark the beginning of a new chapter for the Hudson Tunnel Project. After decades of planning and years of preparatory construction, we will be building the much-needed new tunnel under the Hudson River. The photos from the factory show the size and complexity of the TBMs. We eagerly anticipate seeing these machines fully assembled and ready for launch next year.”

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GDC CEO Tom Prendergast said, “While we may use tunnel boring machines instead of picks and shovels to dig tunnels now, the process of building a concrete tube under a river is still a remarkable challenge. The TBMs that we will use for the Hudson Tunnel Project are massive, highly complex machines, and it took nearly two years of construction to prepare for their arrival. Thousands of people across multiple construction teams are working incredibly hard to reach this important milestone on schedule.”

The TBMs currently being manufactured will be used to build the first mile of the new rail tunnel under the Hudson River, from the New Jersey tunnel entrance at Tonnelle Avenue in North Bergen to the access shaft in Hudson County.

Two TBMs will bore the two parallel tunnel tubes, installing the concrete tunnel liner behind them as they go. Each machine will build approximately 30 ft of new tunnel per day. Including days when mining is paused for maintenance, such as replacing disk cutters in the cutterhead that have been worn down by digging, it will take approximately one year to complete this section of both tubes.

The cutterhead of each TBM measures 28 ft, 8 in. in diameter, and the gantries stretch back roughly 500 ft. Each machine weighs 1,680 tons.

More than 1,000 sensors are placed throughout each machine to monitor the TBM’s position underground, wear and tear on key components, air quality inside the tunnel, and other metrics to ensure safe, efficient tunneling.

This fall, representatives from GDC will travel to the TBM factory to test and accept the machines. Once factory testing is complete, the machines will be shipped to New Jersey. They will be reassembled at the launch point in North Bergen, and tunnel boring will begin in 2026.

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