This is the massive Queens development that Mamdani pitched to Trump — 6 times the size of Hudson Yards

Building a new neighborhood in New York City — with 12,000 affordable apartments, parks, schools and clinics — would be difficult on even the most solid ground. Constructing such a community over a 180-acre train yard is nearly impossible.

The city wants to do it anyway.

Sunnyside Yard, the floundering Queens mega-project proposal, received a boost last week when Mayor Zohran Mamdani met with President Donald Trump. Mamdani said he pitched the president on reviving the 180-acre affordable housing project during the closed-door meeting.

Sunnyside Yard spans 192 acres in Long Island City amid fast-growing residential areas.

It was the largest coach yard in the world when it opened in 1910, and generations of NYC leaders have tried and failed to make something more of it ever since.

Mamdani needs $21 billion in federal investment to make it a reality, according to City Hall.

“In a city where we know that land is so precious and so finite, here lies an opportunity to create more of it, by creating the largest rail deck the world has ever seen,” Mamdani said on Friday.

The final product of Sunnyside Yard, in its current form, would be six times bigger than Hudson Yards on Manhattan’s far west side, and far more expensive.

This isn’t the first time the bold redevelopment plan has been trotted out, but it’s fallen flat each time.

Mayor Michael Bloomberg proposed building massive decks over rail yards and highways back in 2007, with Sunnyside Yard numbering among the possibilities. Officials conceded that a deck on that particular site, however, would require “creative engineering.”

The New York Times recently compared it to building a platform over Roosevelt Island or three Bryant Parks.

Manhattan West, a mixed-use development successfully built over tracks, took nearly a decade to build on just 5 acres. The 28-acre Hudson Yards project took nearly two decades.

Sunnyside Yard re-entered the spotlight in 2015, when Mayor Bill de Blasio announced his intention to built more than 11,000 affordable apartments on a platform overhead. The late architect Robert A. M. Stern called the plan naive.

“It’s just so expensive. The only way you can do that is to support it with a kind of development like we have at the Hudson Yards project with vast, super-scaled office buildings. They are not going to build that kind of building in Sunnyside Yards,” Stern told The Post.

Stern, whose iconic designs dot the New York City skyline, expressed fears the redevelopment would “lead to the re-creation of a kind of large-scale poor district.”

Governor Andrew Cuomo made quick work of rejecting de Blasio’s plan, but de Blasio forged ahead with a feasibility study, the laborious outcome of which was published by the City Economic Development Corporation in 2020, days before the COVID-19 pandemic ground the city to a halt.

The cost, time and effort required to build the megadevelopment aren’t the only barriers to its completion. The plan would require green lights from landowners Amtrak and the MTA, as well as the surrounding community.

Councilmember Julie Won, whose district includes the Long Island City site, has expressed her skepticism.

“Any proposal that reshapes Sunnyside Yards must begin with the neighbors who live here,” Won said in a statement. “Our community deserves a seat at the table long before anyone, including the mayor, makes headlines in the Oval Office especially for a project they have previously rejected.”

Won’s comment added that there are no public approvals in place for the project.

“I welcome the opportunity to build more deeply affordable housing and other federal investments for public transit and other infrastructure, but it cannot be done behind closed doors unilaterally,” she said.

The plan got tentative support from the governor on Friday, as well as positive comments from Representative Alexandria Ocasio-Cortez and the New York Building Congress.

If Sunnyside Yard does indeed find the president’s favor, it will have a long, long road ahead. After all, the 22-acre Atlantic Yards development in Brooklyn, proposed in 2003, has yet to materialize.

The Mayor’s office could not be reached by comment by press time.