Since Hurricane Sandy, New York and New Jersey officials have feared a nightmare scenario where the only train tunnel used by Amtrak and NJ Transit beneath the Hudson River suddenly becomes unusable.

The tunnel is so important that Amtrak warns the entire U.S. economy could be harmed if it were to unexpectedly go offline. Sandy drastically shortened the life span of what was already a nearly century-old tunnel, not designed to handle 450 trains a day.

The saltwater residue left when Sandy’s storm surge receded is an ongoing worry 10 years later.

But a decade after the storm, the North River Tunnel remains just as vulnerable to flooding. A $16 billion plan to repair the existing tube and build a new one won’t be complete until 2038.

Officials from New York, New Jersey, and Amtrak involved in the project, dubbed the Gateway Program, now admit they can do little more than cross their fingers that another flood won’t hit in the meantime.

“There’s only so much we can do physically to protect the existing infrastructure. It's been there since 1910, and obviously we're in a very dense part of the country,” said Amtrak spokesperson Craig Schulz. “It's not like we can do a whole lot.”

A crack near a third rail in the North River Tunnel in 2014. Water has penetrated the bench wall of the tunnel, disrupting service.

Senate Majority Leader Chuck Schumer has likened the North River Tunnel linking Penn Station to New Jersey to an “aorta” that “connects one side of the Hudson to another and connects Boston to Washington.” Before the pandemic, Amtrak and NJ Transit trains carrying a total of 200,000 passengers used the tunnel daily.

“We were very lucky during Hurricane Sandy. We may not be as lucky next time,” said John Porcari, the first head of the Gateway Project.

He’s a consultant now and says Amtrak got lucky because the North River Tunnel can still be used today. Amtrak hopes that once the tunnel is upgraded it’ll be good for another 100 years, but Porcari warns there are many ways the tunnel could be damaged again as climate change causes rising sea levels and more damaging storms.

“It's important to point out that the particular failure mode that flooded the tunnel during Sandy is just one vulnerability,” he said. “Different types of storm events, different tidal action can result in other failures. We should all feel a sense of urgency to get the new tunnel open.”

During Hurricane Sandy, millions of gallons of water entered the North River Tunnel via a ramp connected to an aboveground train yard about 300 feet from the Hudson River. The tunnel became a basin for water that otherwise would have flooded Midtown and Penn Station.

Water from Hurricane Sandy flooded the tunnel in 2012, causing damage that still has not been repaired 10 years later.

Seawater submerged the concrete wall that holds electric cables carrying 12,000 volts of electricity to trains.

Two years after the storm, the former head of Amtrak admitted the tunnel had about 20 years of useful life left. That year, pieces of the bench wall fell on the tracks, causing major delays.

The saltwater had corroded the concrete, creating small holes where water can seep in and wreak havoc when it comes in contact with the power cables.

In 2015, a series of cables exploded, snarling train traffic throughout the Northeast Corridor and taking weeks to repair.

An Amtrak employee shows a cable from the North River Tunnel that exploded after coming in contact with water.

“Since Sandy, they’re keeping their fingers crossed. [The cables] are failing with increasing frequency – several times in the past 10 years or so,” Schulz said.

The MTA is looking for contractors to design a flood wall and other protections from water at the West Side Yard by Penn Station. But that plan's primary purpose is to protect MTA trains and equipment, not prevent flooding in the North River Tunnel.

Moisture in the North River Tunnel below the Hudson River in 2014.

For its part, Amtrak is making small repairs and fixes where it can to keep the tunnel safe. It cleans troughs under the tracks so water can properly drain. It grouts cracks to prevent water leaks. There’s a $150 million rehab program underway.

The new tunnel, expected to be complete in 2035, will be built to current flood prevention standards. Once it’s up and running, Amtrak plans to spend another three years fully rehabilitating the old tunnel. It will install new rails, replace the old cables, and put them in a concrete bench wall that’s higher off the ground.

New Jersey Gov. Phil Murphy has called conditions in the tunnel “alarming.”

“We are sitting on a transportation ticking time bomb,” New Jersey Sen. Bob Menendez said in 2019. The influential Regional Plan Association has called Gateway “the nation’s most urgent infrastructure project.”

The North River Tunnel connecting Penn Station to New Jersey has been likened to the "aorta" of the Northeast Corridor.

But urgency surrounding the project has varied depending on the party in power.

Former President Barack Obama supported the new tunnel project, but failed to secure funding and move it forward. Former President Donald Trump stalled the project during his four years. Now, President Joe Biden has money in his infrastructure bill that’s expected to help fund the Gateway Program.

In August, ground broke on the first part of the Gateway Program: a replacement for the Portal North Bridge, even if it was the third time ceremonial shovels marked the “start” of the project.

But Gateway also needs the governors of New York and New Jersey to each cover a quarter of the costs as well. They’ve said they will. But Murphy and Gov. Kathy Hochul are also clashing over other projects, like congestion pricing and Hochul's $7 billion Penn Station redevelopment project.

With the midterm elections coming up, the Democrats could lose control of one or both chambers of Congress and support for a $16 billion tunnel project in the Northeast could dry up.

“You know If there's nothing we can do to prevent water from coming into them [the tunnels], at least we can build other ones and more of them to better handle water or to have a detour around problems,”. “So that we're not so reliant on a single point of failure, right?” said Schulz, the Amtrak spokesperson.