Work has begun on the massive new Hudson River Gateway rail project between New York and New Jersey — as the feds said Friday they will be coughing up another $3.8 billion to complete the improvements.

The new funding breathes life into the long-stalled transit plan, which costs $16.1 billion in total and will double the number of train tracks running between New York and New Jersey, officials said at a press conference announcing the cash infusion Friday.

“It’s all systems go, there’s no turning back,” said US Senate Majority Leader Chuck Schumer (D-NY), calling the Gateway project the “most consequential infrastructure project in all of America.”

“With all these new dollars, Gateway is secure,” Schumer added.

The new link is expected to be completed by 2035 with the rehab of the existing tunnel to be completed over the following three years, officials say.

When the two-step project is over, the three major railroads will have four tracks they can use to run trains between New York and New Jersey, meaning that if there’s a breakdown or a problem on one track, it won’t cripple service across the entire Northeast.

Schumer, New York Gov. Kathy Hochul, US Transportation Secretary Pete Buttigieg and other dignitaries gathered near the West Side Rail Yards to hold a Friday morning press conference where they celebrated scoring another $3.8 billion in federal funding for the effort.

All told, the federal government and Amtrak have promised or provided roughly $12 billion in funding, which accounts for three-quarters of the price tag.

The rest of the cost will be split between Albany and Trenton.

Additionally, officials said they are beginning construction on the underground linkage between Penn Station and the to-be-built tunnel.

The project, which is governed by the Gateway Development Commission, puts the price tag at $16.1 billion; however, federal regulators have warned that the figure could grow to $17.2 billion, depending on interest rates.

Officials argue that reliability issues with the current tunnel alone make the Gateway Project essential even in a post-pandemic world, where working from home means that commuter railroads and the subways have only brought back 70 to 80 percent of their weekday ridership.

Those pre-pandemic trains were packed to the point of overcrowding as commuters were forced to stand in the aisles, while the railroads tried to shove so many trains into the existing two-track tunnel that any delay quickly wrecked schedules for the entire commute.

The new tracks, officials say, will fix the reliability issues as well as one of the biggest bottlenecks that forced riders for years to change trains in Newark or switch to ferries or the PATH at Hoboken to come into Manhattan.

However, one major jam remains: Penn Station itself.

The West Side rail hub can only fit up to 24 trains per hour running under the Hudson River as it is currently configured and operated. The new tunnel and tracks could fit 48 or more. 

The MTA, Amtrak and New Jersey Transit have tentatively pitched a controversial plan that would spend potentially $17 billion to build a massive, 12-track expansion to the immediate south of the current station to fit the larger schedules.  

However, advocates have demanded the railroads come up with a plan that squeezes more capacity out of the existing station complex. 

The MTA internally developed a program that could increase the existing station’s capacity by as much as 45 percent by improving the signal systems and, most crucially, having the railroads run more efficiently and cooperate more closely on schedules and service.

It would cost just a fraction of the Penn South price tag, at approximately $3 billion. 

However, it was shelved in favor of the larger terminal proposal that would allow each agency to essentially keep its own fiefdoms at Penn.