A long-sought but long-opposed bridge or tunnel across the Long Island Sound is not in a multibillion dollar federal plan to bolster the Northeast Corridor rail line, according to the latest project update released Wednesday.

Instead, the Federal Railroad Administration’s Northeast Corridor Future project will spend between $120 billion and $150 billion on a “corridor-wide vision” to improve rail service, modernize corridor infrastructure, and expand rail capacity, officials said.

Building a bridge or tunnel across the Sound has been a dream of some Long Islanders and a nightmare for others for decades.

At a cost of $290 billion, the latest crossing proposal would have given LIRR riders direct and quicker access to New England, with two new tracks extending north at Ronkonkoma to cross the Sound into New Haven, Connecticut.

The proposal made it into the final four options in 2015 for the federal agency’s plan — down from about 100 considered.

In its place, the less expensive project, is moving ahead, according to the update. The nearly 500-mile Northeast Corridor line stretches from Washington to Boston and is the busiest rail corridor in the country, serving more than 750,000 riders daily.

The Sound crossing proposal didn’t make the cut for “various reasons . . . including the high cost relative to the travel-time savings and other benefits,” an FRA spokeswoman wrote in an email Wednesday.

Some Long Island residents in early 2016 had expressed concerns about the scope of the project, which would have snaked through dense, residential regions.

While various projects listed in the Future plan are in the works through 2040, some in New York City are already in motion.

Large-scale undertakings include the MTA’s Harold Interlocking and East Side Access projects, which seek to ease and divert traffic buildup around Manhattan’s Penn Station. The transit hub is a major stopping and connecting point along the corridor with an anticipated 70 percent growth in ridership by 2040, according to the FRA.

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The Harold Interlocking project in Queens will “construct new conflict-free train routes for Amtrak along two miles of the Northeast Corridor” to improve high-speed rail travel, according to the MTA website. Harold Interlocking — a massive rail junction in the Sunnyside section of Queens, currently forces Amtrak service to compete with local trains by having both entities cross over mainline tracks.

The $10.178 billion East Side Access project, which the MTA is also managing, will extend Long Island Rail Road service to the Eastside of Manhattan via an eight-track terminal and concourse below Grand Central Terminal, according to the MTA’s website.

The new terminal and tracks are expected to be in service by December 2022.