The Long Island Rail Road is embarking on a major study that could shape the kind of service it will offer in 25 years.

LIRR president Patrick Nowakowski on Monday detailed the two-year “network strategy study,” which aims to predict ridership patterns from 2025 through 2040, and come up with ideas to meet that demand.

The last study of its kind, conducted in the early 1990s, inspired the LIRR’s fleet of double-decker train cars and the decision to go forth with East Side Access — the MTA’s $10.2 billion effort to bring the railroad to Grand Central Terminal by 2022.

The new study, being conducted by Los Angeles-based planning firm AECOM, looks ahead to life after East Side Access, LIRR officials said.

“We need to get ready for that,” Nowakowski said at a meeting of the Metropolitan Transportation Authority’s LIRR Committee. He said the new survey, which is expected to be completed in mid-2017, will be more ambitious than the original one two decades ago.

“This is going to be a more extensive and more detailed look and it involves very close coordination and information gathering with the counties on their vision for where we expect the Long Island Rail Road to go,” Nowakowski said.

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LIRR executive vice president Elisa Picca said in the study’s first phase the railroad will meet with Long Island’s “thought leaders” and listen to issues and ideas. Later, the LIRR will whittle down those ideas and look at them more closely, including through operation simulation, ridership forecasting and financial analysis.

Picca said among the issues that could be addressed are expanded electrification throughout the LIRR system, how to reduce the need for transfers and how to expand capacity.

The goal, Picca said, is to “look forward and see what are the markets that we’re serving, how are we serving them, what are the changes in dynamics and demographics and behavior and travel patterns that are going on in our region and are we set up to capture those needs?”

Sheldon Sackstein, chairman of Action Long Island, a Melville-based planning group, said the study provides an opportunity to discuss ideas both simple and complex, including his proposal to study building an underground extension of the LIRR along the Route 110 corridor in Suffolk.

“I’d love to sit down at the table with a clean sheet of paper and envision all the opportunities — some being more grandiose than others,” Sackstein said.