NEW YORK — Some beleaguered passengers who will be inconvenienced by planned summer repair work at Pennsylvania Station might have used Grand Central Terminal — if new suburban commuter rail tunnels were ready.

But the latest estimates for that undertaking are that it won’t be operational until 2022, 13 years after the original completion date.

The agency that runs the Long Island Rail Road, the busiest commuter railroad in the country, has spent more than a decade carving out tunnels and a massive subterranean cavern that will bring suburban trains beneath the East River to Grand Central in Manhattan. Besides being more than a decade behind on construction, the East Side Access Project is billions of dollars over budget.

‘‘Had East Side Access been completed on time, there would have been redundancy in the system and would have alleviated pressure on the system,’’ said Victoria Vanterpool, executive director of the Tri-State Transportation Campaign.

‘‘That would have been important route as a backup,’’ said Vanterpool, who recently joined the board of the Metropolitan Transportation Authority, the agency responsible for the project.

So for now, Long Island Rail Road passengers bound for Manhattan are stuck with Penn Station, which handles an estimated 600,000 passengers each weekday.