Summary
At the base of the Palisades in North Bergen, New Jersey, there’s a wall of hard, dark volcanic rock. For millions of years it has stood between the New Jersey Meadowlands and the Hudson River. This fall, a machine longer than a football field started pushing its way into it. The machine is the first of two giant tunnel boring machines, or TBMs, for the Hudson Tunnel Project. On September 28, officials held a ceremonial launch for the $16 billion project’s tunnel boring. After final testing, the first machine began cutting the first new rail tunnel toward the Hudson in more than a century, with the second set to follow. Shipped in pieces, rebuilt on site Both machines were custom-built by Herrenknecht, a German company that makes many of the world’s largest tunneling machines. They’re far too big to ship in one piece. Each machine was broken down into 96 separate parts for the trip across the Atlantic, landing at ports in New Jersey and Baltimore before being trucked to the construction site. Reassembling them was a major job in itself, and it didn’t go smoothly. Earlier in 2026, work on the project stopped during a funding dispute with the federal government. The machine parts sat in crates until federal funding was restored and crews could get back to building. Fully assembled, each machine weighs about 1,680 tons. The rotating cutterhead at the front is 28 feet, 8 inches across, and the trailing equipment behind it stretches back roughly 500 feet. How a tunnel boring machine works A TBM is essentially a moving underground factory. At the front, the cutterhead spins slowly against the rock face. It’s studded with hardened steel disc cutters, which crack and chip away the stone as the machine pushes forward. The broken rock is carried back through the machine and out of the tunnel. Just behind the cutterhead, a steel shield protects the crew and equipment. As the machine advances, it installs curved precast concrete segments, bolting them together into rings that form the tunnel’s permanent lining. The Hudson tunnel machines are “single shield” TBMs, a design suited to hard rock like the Palisades. Each one carries more than 1,000 sensors that track the machine’s position, wear on key parts and air quality inside the tunnel. That lets operators steer precisely and spot problems before they cause breakdowns. About 30 feet a day The machines are expected to advance about 30 feet a day each, including stops for maintenance. That sounds slow, but in hard rock it’s steady progress, and the tunnel is fully lined as it goes. The two machines will bore parallel tubes for roughly one mile, from the tunnel entrance at Tonnelle Avenue in North Bergen to a large access shaft in Hudson County, near the river. Other machines and contracts will handle the section under the Hudson itself and the connection into Manhattan. By size, these TBMs sit in the middle of the pack. They’re much smaller than “Bertha,” the 57.5-foot machine that dug Seattle’s SR 99 highway tunnel. But they’re larger than the machines used for New York’s East Side Access rail project. Why the Hudson needs a new tunnel Right now, every Amtrak and NJ Transit train between New Jersey and Penn Station in Manhattan uses a single pair of tubes, the North River Tunnels. They were built in the early 1900s and opened in 1910. In 2012, Hurricane Sandy flooded both tubes with saltwater, which has been slowly damaging the concrete and electrical systems ever since. The tunnels still work, but they need a major overhaul. That can’t happen while they’re the only way across, because closing even one tube would cripple train service on the busiest rail corridor in the country. The Northeast Corridor handles more than 2,200 train movements and about 800,000 passenger trips a day. The plan is to build two new tubes first, move trains into them, then take the old tunnels out of service one at a time for repairs. When everything is finished, the river crossing will have four tracks instead of two. A long road ahead The new tunnel won’t carry trains for years. The full Hudson Tunnel Project is expected to take until the mid-2030s, and big infrastructure projects rarely stick perfectly to their schedules. Still, the start of boring is a real turning point. After decades of planning, political fights and preparatory construction, the project has moved from paperwork to rock. And at about 30 feet a day, the machines are finally doing what this stretch of track has needed since before anyone alive today was born.