The MTA Board gave a unanimous go-ahead Wednesday for the $2.6 billion Third Track project.

Work on the long-sought after project to add a third track to 9.8 miles of the Long Island Rail Road’s Main Line between Floral Park and Hicksville will begin immediately.

A third track was pitched in the late 1980s and again in 2005, but was shot down by community opposition and lack of support from elected officials in western Nassau County.

This time, however, the plan adds an estimated $1 billion in ancillary improvements, including the elimination of seven grade crossings and new train stations at New Hyde Park, Merillon Avenue, Mineola, Carle Place and Westbury. It also includes six new parking structures in Mineola, Westbury and Hicksville that will add 2,300 new commuter parking spaces. In addition, sound attenuation walls will be constructed through all residential neighborhoods that border the tracks.

The design build contract, estimated at $1.8 billion, has been awarded to a group that includes Dragados USA, John P. Picone Inc., China Civil Construction and Halmar International. The design engineer on the project will be Stantec and Woodbury-based Cameron Engineering will be a sub-consultant.

“We’re very excited to work on this major transformative project for Long Island,” said Cameron Engineering principal John Cameron.

Congestion of trains heading east and west and massive vehicle traffic tie ups at grade crossings was the impetus for the project. The same two tracks that served a Long Island population of about 50,000 people in the 1840s are the same two tracks that serve a population of about 3 million today. While there were just two tracks running through the Main Line 170 years ago, there are now four additional LIRR branches that converge on its Nassau section.

The additional track will allow for better service, especially when it comes to reverse commuting of employees coming from New York City to Long Island.