After four years of stalling by the Trump administration, officials in Washington approved the $11.6 billion project for federal funding.
For five years, the plan to build a second pair of rail tunnels between New York City and New Jersey has been deemed one of the most critical infrastructure projects in the country.
But it needed a green light from federal officials.
On Friday, after years of delaying by the Trump administration, that approval officially arrived from the new administration in Washington. Now, much of the $11.6 billion needed for the tunnel project could come from the giant infrastructure bill that Republican and Democratic lawmakers are wrangling over in Congress.
“We’re now where we should have been four years ago,” said Steven M. Cohen, co-chairman of the Gateway Program Development Corporation, the agency overseeing the project. “All of this has been in suspended animation for four years for no reason other than politics and games.”
The Biden administration has indicated its support for the long-tortured project, which has been contemplated in various forms for nearly three decades. On Friday, the transportation secretary, Pete Buttigieg, acknowledged its importance to the economy of the region and the nation.
“This is a big step for the Northeast, and for the entire country, as these tunnels connect so many people, jobs and businesses,” Mr. Buttigieg said in a statement announcing the approval.
Still, as with many major infrastructure plans in the early stages, there are still uncertainties, especially around the finances. Ambitious transportation projects in the region have often ballooned in cost as construction delays or design changes drove up the final tally.
While the governors of New York and New Jersey have agreed to share the cost with the federal government, both have elections looming. If they leave office, there is no assurance their successors will uphold that commitment.
The one-track tunnels, which would carry trains deep under the Hudson River, are part of a massive project known as Gateway that aims to modernize the rail system that serves New York City. They would supplement the existing single-track tunnels that are more than 110 years old and were severely damaged during Hurricane Sandy in 2012.
Under the existing construction timetable, the new tunnels would be built in eight years. But the planners hope that they could be finished long before the end of the decade.
Before the pandemic, 450 trains carried about 200,000 passengers each weekday through the old tubes, which connect to Pennsylvania Station in Manhattan. Most riders were commuters, but many others were traveling from other cities on Amtrak, the national railroad that owns the tunnels and Penn Station.
Since the hurricane, transportation officials in the New York region have worried about the deteriorating condition of the existing tubes under the Hudson. Salt left over from the flooding has been eating away at the interior walls and electrical cables, forcing occasional shutdowns for repairs.
Amtrak officials say that the old tubes cannot be fully fixed until there are new ones to handle the daily traffic. About $1.8 billion of the $11.6 billion estimated cost for the tunnel project would go toward overhauling the old tubes, they say.
The idea of building the tunnels has been a political football for years. Democratic politicians have promoted it as a critical piece of the nation’s transportation infrastructure that cannot be realized without significant aid from Washington. But some Republican leaders saw it as a gift to New York and a potential boondoggle that could wind up costing much more than advertised.
During Barack Obama’s presidency, there had been a general agreement that the federal government would cover half the cost of building the tunnels, with New York and New Jersey sharing the other half. That commitment from the states still stands, said Anthony Coscia, the chairman of Amtrak.
The two states had intended to borrow much of their shares of the cost from the federal government, a standard practice in big, expensive projects. But the Trump administration ruled that such borrowings would not count as contributions from the states. The Biden administration quickly reversed that position in February, clearing one hurdle for the tunnel project.
A bigger hurdle was the lack of a response to the application from the project’s sponsor for a decision on its environmental impact statement. That decision could have come as far back as 2018, Mr. Coscia said.
But the federal Department of Transportation, which under President Trump was headed by Elaine Chao, did not respond to the application, despite repeated entreaties from Mr. Coscia and elected officials from New York and New Jersey. That stonewalling was the second major setback to a plan that dates back to the 20th century.
In a previous incarnation, the concept was known as the A.R.C. tunnel and it was going to lead not to Penn Station, but to a new terminal deep beneath 34th Street, near Macy’s flagship store. Construction had begun on that tunnel, with federal backing, when New Jersey’s former governor, Chris Christie, ordered a halt.
Mr. Christie, a Republican, argued that New Jersey would have been responsible for any cost overruns, which could have amounted to an unfair and unaffordable burden to the state. Democratic leaders from both sides of the Hudson were furious that Mr. Christie had passed up billions of dollars of federal money that would have flowed to the region.
Senator Chuck Schumer of New York, who is now the majority leader, was among them. From the start, Mr. Schumer has been an ardent champion of building a modern rail link to New York City. He pressed the Trump administration for approvals and funding, to no avail.
Now, with an ally in the White House, Mr. Schumer promised he will shepherd the Gateway program toward completion. Altogether, Gateway involves expanding Penn Station and adding tracks beneath it, as well as making improvements along the Northeast rail corridor, including replacing a 111-year-old swing bridge in New Jersey.
Mr. Christie’s successor, Philip D. Murphy, a Democrat, has staunchly supported the Gateway plan. His counterpart in New York, Andrew M. Cuomo, has at times raised doubts about his commitment to the tunnel project while he has focused on redeveloping the blocks around Penn Station.
But Mr. Cohen, a close ally of Mr. Cuomo, said on Friday that the governor would stick with the formula that calls for each state to cover 25 percent of the costs. He said Mr. Cuomo, “made it clear that whether he thought it was a good deal or not, he was not going to trade on that.”
Mr. Schumer sounded exuberant in a brief interview about the pockets of federal money that could be used to pay for the tunnels. He cited $25 billion in the infrastructure bill known as the American Jobs Plan that is intended for “transit expansion,” $39 billion for “Northeast Corridor modernization” and $25 billion for projects of national significance.
“Not only have we gotten the barriers lifted, but we have also now made sure there is plenty of money in the pipeline,” Mr. Schumer said. “I’m going to use my clout as majority leader to make sure they go there,” he added, referring to Gateway.
A few weeks ago, the Biden administration signaled that a decision on the project was coming soon. But its official arrival provided long-awaited relief to those who have been planning the tunnel project for eight years.
“This approval means a lot of things,’’ Mr. Coscia said, “but what it really means is that it’s time to stop talking about this project and it’s time to start building it.”