After a brief interruption in funding due to a dispute with the US Department of Transportation, the Hudson Tunnel project is back on track, officials say. Crews are moving toward assembling the first set of tunnel boring machines (TBMs) to be deployed on the $16 billion project.
The schedule for the regional megaproject was in jeopardy earlier this year when the U.S. Department of Transportation withheld federal funds previously awarded to the Trump administration. Those funds were eventually released, but the full impact of the disruption on costs and schedule is still being calculated, project officials tell ENR.
But the larger program has been able to regain some momentum in recent weeks, helped by the fact that it is being developed through separate contracts, they add.
“The Hudson Tunnel project has ten projects,” explains James Starace, head of program delivery for the Gateway Development Commission. “Of the ten projects, five are under construction with a different completion.”
Photo by Jeff Rubenstone/ENR
The Tonnelle Avenue Bridge in North Bergen, NJ, where an embankment under a bridged roadway was replaced to allow rail service below, is now complete. Other ongoing work includes soil stabilization efforts in the Hudson River; the construction of the access shaft on the 12th Avenue side of Manhattan; conventional excavation of the tunnels connecting this well to Penn Station; and the current focus of the project: digging twin tunnels through a mountain on the New Jersey side to the shore of the Hudson River.
Preparing for the launch of a TBM
At the Tonnelle Avenue site, work now focuses on preparing the launch pit for the pair of tunnel borers that will dig a mile through a mountain to reach the Hudson River. A $465.6 million contract for these side tunnels in New Jersey was awarded in 2024 to the Schiavone Dragados Lane joint venture.
Two Herrenknecht TBMs have been delivered to the site and are being prepared for assembly and launch. Starace confirmed to ENR that the Germany-based manufacturer had already delivered one TBM to the site and had the other in production when federal funding was cut off earlier this year. ddespite the legal dispute over the financing of the project, Herrenknecht did not delay the delivery of the second tuner, he says.
Once the tunnels start boring, it’s 5,100 straight feet through the solid rock of the Palisades Sill. At a projected progress rate of about 30 feet per day, boring the tunnels is expected to take about a year. Each TBM includes an erector that places 6-foot precast concrete tunnel linings as it bores the tunnel, allowing the machine to advance in approximately 6-foot increments.
The twin TBMs will eventually traverse to a prepared access shaft in Weehauken, NJ, near the banks of the Hudson River.
The two single-shield TBMs feature 28-foot, 8-inch-diameter cutting heads with 500-foot-long gantries behind them. Crews operate the TBM from an indoor control cabin to keep it on target, as the segmented TBM is capable of course corrections to its trajectory. The hard, abrasive mountain rock will also require regular replacement of each cutting head’s 59 tungsten carbide cutting wheels, whose performance can be monitored from the control cabin.
Each TBM is assembled from 96 segments, some weighing up to 185 tons, which require heavy-duty cranes to lower them into the launch pit for assembly. Ground stabilization and bearing construction for these high-capacity cranes is underway. No launch date has yet been set for the TBMs to begin boring, but the goal is to start “as soon as possible,” says Starace.
Once the Palisades tunnels complete their journeys and are removed, the Weehauken shaft will serve as the launching point for the tunnels that will pass under the Hudson River to New York City.
The contract to drill the twin tunnels under the Hudson River has not yet been awarded. But the project’s chief engineer, Hamed Nejad, points out that the work will involve a completely different set of tunnel borers, custom-made to suit the geological conditions of each site. Unlike the hard rock of the Palisades Sill, the soft soils of the Hudson River will require grout injection and soil freezing.
“We ask this question a lot: ‘why not use the same machines?'” says Nejad. “The next part of the tunnel is a combination of rock and soft [materials] which only gets smoother. We have to buy a whole new machine to suit the conditions of this place.”
Back at the launch site, preparatory work is already underway to build a mud pit to collect the spoil that will be ejected from the back of the TBMs. As of this week, there is still about 75 feet of rock wall to be excavated by conventional means before the tunnelers can be lowered and set up. The site’s workforce has been fairly steady at 60 to 70 people during this phase, but Starace says that will likely increase once the tuners are launched.
There are still many tunnels ahead
The consistent hard rock of the Palisades Sill allows the team to plan a fairly consistent boring. The real planning to address the risk of unknown conditions is for the Hudson River Tunnel segment, especially as it approaches the Manhattan coast. “The West Side of Manhattan from 8th Avenue [westward] Everything is a reclaimed landfill,” explains Nejad. “There are old ports, ship anchors. If a TBM hits any of these ship anchors, it will not pass through them. To de-risk the job, we need to stabilize this ground.”
This means excavating west from the 12th Avenue well toward the river with a bulldozer shield to remove potential obstructions. Once completed, this space will be filled so that river TBMs can drill through uniform material without any surprises, Nejad says. Last year, the Frontier Kemper-Tutor Perini joint venture was awarded a $1.18 billion contract for the Manhattan axis, as well as digging the tunnel to connect it to the existing tunnels at Hudson Yards.
