If you’ve walked or driven along the Hudson River recently, you may have noticed some barges with large cranes near the New York shoreline.

The work is part of a major phase of the Gateway Tunnel, the first new rail tunnel under the Hudson River in 114 years.

What You Need To Know

  • A concrete casing is being built 1,200 feet from New York’s shoreline for boring machines to tunnel through to New Jersey

  • The engineering used is similar to that of the early 1900s, when the North River tunnel was built, but instead of sheer manpower, they're using machines

  • Regulations around sturgeon migration limit when the work is being done

“Ultimately what we’re doing here is we’re building 1,200 feet of essentially a concrete lightweight box at the bottom of the Hudson River in order for the tunnel boring machines — the two tunnel boring machines — to be able to go through and get to Manhattan,” said Stephen Sigmund, chief of public outreach for the Gateway Program.

NY1 got an exclusive look at the construction site in the Hudson River, where work is happening alongside projects in Hudson Yards and New Jersey to prepare for the long-awaited infrastructure.

“The consistency at the bottom of the river is almost like chocolate pudding and it would collapse in on the tunnel itself,” Sigmund said. “So, it shows you, again, how complicated a project this is. It’s not just about drilling some holes in the ground and in the river.”

Crews have constructed over 140-feet-long cofferdams — a temporary dam made with more than 100 interlocking steel sheet piles driven into the ground — to create an environment for construction.

“They create a calm surface to do the work,” Sigmund said. “Otherwise, as you can see… the Hudson River is rough and full of currents and fish and all sorts of things that would make it difficult to do this kind of work.”

Inside the cofferdam, machinery pumps a mix of concrete, soil and water into columns to form the tunnel's casing. The main difference between the engineering now and when the North River Tunnel was built in the early 1900’s is the use of machinery versus sheer manpower.

Additionally, current work must comply with regulations to protect sturgeon migration in the river.

“Nobody was too worried about the sturgeon in 1900,” Sigmund said.

The tunnel casing is expected to be finished by 2027, in time for the boring machine to come through. And when the Gateway Tunnel opens in 2035, it will allow for a rehab of the current tunnel, one tube at a time, to solve the problem of service disruptions from trains getting stuck in the only tube in or out of Manhattan.

“Once this is built, by 2035, there will always be three tubes in operation in the next three years,” Sigmund said. “And by 2038, you will have four tubes available in operation, and reliable.”