The MTA was warned a decade ago that the Long Island Rail Road’s Jamaica hub would be overwhelmed and face frequent commute meltdowns — like the ones commuters have been forced to endure all week, The Post has learned.

The dire prediction came in an analysis of the Jamaica, Queens station’s capacity, completed in 2012, that simulated service changes nearly identical to the one launched by the MTA this week to its new $11 billion terminal on the East Side of Manhattan and found it would overwhelm operations at the station.

“Evaluation of the new operation on the existing conditions indicates an inability of the current infrastructure to accommodate the higher volume of service during the morning peak period and evening westbound direction due to cascading delays,” the analysis determined.

The simulation showed trains arriving into Jamaica on-time 93% of the time under the then-current runs, even when encountering routine service disruptions, like a medical emergency on a platform or a mechanical problem with a train.

But the on-time percentage with the new service plummeted to just 72%, a 21% drop, the analysis prepared by San Diego-based TranSystems Corporation determined.

The prophetic study found that the operational collapse occurred even if the MTA simplified the Jamaica operation by axing one-seat service from Long Island to Brooklyn and instead ran a shuttle to Atlantic Terminal — and even if officials axed timed transfers to boost station capacity by reducing the amount of time trains spend parked at the platforms.

The solution, the analysis determined, was to replace the low-speed switches that run through Jamaica Station — which limit trains to just 15 mph — with more modern systems that allow trains to run at 30 mph or faster.

MTA officials approved spending $85 million to do just that in 2020 — some eight years after the engineering report was completed. That project is not expected to be completed until December 2027.

It does not appear that the MTA ever made the analysis public, but it was heavily excerpted in an academic article that the firm subsequently prepared, which was published in 2014.

It was a time of extraordinary turnover at the agency.

Former MTA chairman Pat Foye had only been on the job for a few months; ditto then-LIRR president Phil Eng, who was appointed to the job in 2018 after an operations meltdown cost Patrick Nowakowsk the job. Eng quit in 2022.

The current MTA chairman, Janno Lieber, had only been appointed the head of the agency’s major projects division in 2017.

“If that report is valid, then the railroad shot themselves in the foot,” said Gerry Bringmann, a non-voting member of the MTA Board of Directors who heads the LIRR Commuter Council.

In a statement, the MTA said that it had “factored existing infrastructure” into the schedules it drafted to begin full service to the new east side terminal, formally known as Grand Central Madison.

“The LIRR increased weekday service from 625 trains per day to more than 900 trains per day and has factored existing infrastructure into that effort,” said MTA spokesman Michael Cortez.

In Queens, outrage over the schedule changes continued to build for a fifth straight day at Jamaica station Friday and among state lawmakers in Albany.

“This week has been crazy,” said Katterin DeLaCruz, a 28-year-old teacher who commutes from Brentwood to Brooklyn and now has to do her classroom preparations the night before instead of in the morning. “I would like to be able to rest before the students come in and do stuff if I need to.”

Another rider, a 40-year-old construction worker, Jahim Gibbs, said he had to run from one end of the station to the other to catch the shuttle to Atlantic terminal.

“I ran into a friend,” he recounted Friday. “He said, ‘You are going to Brooklyn?’ I said, ‘Yes, but I don’t see the train.’ He said, ‘It’s on [Track] 11. I had to run that whole long trip just to get to 11.”

He added: “I didn’t know there was even a Track 11. It was news to me. I thought it was from 1 to 8.”

Lieber, for his part, apologized to riders during a state budget hearing in Lower Manhattan and promised that tweaks to the schedule coming next week will help alleviate the overcrowding on the trains to Penn Station and Atlantic Terminal.

“We’ve had a tough, tough week on the Long Island Rail Road,” the MTA’s top boss told state Senators during the hearing. “We have to fix what’s diminished our riders’ confidence.”

The MTA announced that it was adding three more LIRR morning shuttle trains to Brooklyn, which will run at 7 a.m., 7:29 a.m. and 8:09 a.m.

Meanwhile, Republican lawmakers who represent Nassau and Suffolk counties also took aim at Gov. Kathy Hochul, who inherited the project and much of its timeline from disgraced Gov. Andrew Cuomo when she took office in 2021.

“As usual the photo ops of officials riding into the shiny new stations go off without a hitch while the actual daily riders must be patient,” tweeted Assemblyman Ed Ra (R-Nassau).

Hochul backed Lieber and the MTA when pressed about the meltdown by reporters after an event near Albany.

“Our MTA leadership has been literally on the ground, assessing the length of the trains, the frequency of the trains,” she said. “I think if the public is just willing to give us some time to make the necessary adjustments, we’ll get it right.”

Additional reporting by Georgett Roberts and Zach Williams