The Long Island Rail Road -- already the largest commuter railroad in the United States -- just got a little bigger.

LIRR officials Thursday unveiled the first stretch of new rail laid as part of the agency's long-awaited Double Track project between Farmingdale and Ronkonkoma.

In a statement, Gov. Andrew M. Cuomo said that "after decades of talk" he was proud to see the project "become a reality."

"Today, we take action to help alleviate congestion on one of the Long Island Rail Road's busiest lines and improve the commute for the tens of thousands of Long Islanders who depend on it," Cuomo said Thursday. LIRR officials have said doubling the capacity on a portion of the Ronkonkoma Line -- used by 48,000 riders each weekday -- will allow the railroad to operate more trains and more quickly rebound from a service disruption in the area. Currently, if a train breaks down on the single-track section of the line, the LIRR has no way to route trains around it.

"It's an incredibly exciting day for the region," Suffolk County Executive Steve Bellone said at a ceremony where the new tracks were installed. "The Double Track project is critical to everything we're trying to do from an economic development perspective."

Although construction work on the project began last year, until now much of it involved clearing and preparing the LIRR's right of way. The 200-foot section of track, laid just west of Ronkonkoma, is the first section of nearly 17 miles of track to be added as part of the project.

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In its first phase, estimated to cost $138 million, the new tracks are expected to reach as far west as Central Islip by 2017. The second phase, which includes designing a new LIRR station near Republic Airport in East Farmingdale, is slated to cost $250 million and be completed by 2019. But that's far from a given.

The LIRR wants to complete Double Track as part of the Metropolitan Transportation Authority's $27 billion proposed 2015-2019 Capital Program. But the plan is yet to be fully funded or approved by the state.

"Getting this first phase done is a part of the project. Obviously, the key thing we need now is getting the '15-'19 program approved," LIRR president Patrick Nowakowski said. "It's not until the second phase is done that riders can really get all the benefits."

LIRR officials said Double Track is a boon for Long Island in other ways as well. The railroad estimates that, by the time it is completed, the project will have created 1,000 jobs and injected $100 million into Long Island's economy.

"This is bringing jobs. This is bringing better service," said Anthony Simon, head of the LIRR's largest labor organization, the Sheet Metal, Air, Rail and Transportation Workers union. "This project is going to be big."