The Atlanta Beltline Inc. has been awarded an $18 million federal transportation grant to develop a 2.5 mile portion of the greenspace project in southwest Atlanta, city officials announced this week.

The grant means the Southwest Corridor will open in two to three years, versus five without it, Atlanta Beltline spokesman Ethan Davidson said.

The Transportation Investment Generating Economic Recovery, or TIGER, grant is the first of its kind for the Atlanta Beltline and the second TIGER grant Atlanta officials have received in recent years. The city received a $47.6 million award for the streetcar project in 2010.

“The Atlanta Beltline is one of the most transformative projects ever undertaken in our city’s history,” Atlanta Mayor Kasim Reed said in a statement, thanking President Barack Obama and U.S. Secretary of Transportation Anthony Foxx for selecting Atlanta to receive the funds. “This $18 million grant is a tremendous step forward in my administration’s goal to make the vision of the Atlanta Beltline a reality much sooner.”

Beltline officials said the money will help the nonprofit purchase a stretch of trail — a former freight rail line — currently owned by the Georgia Department of Transportation. According to city officials, the TIGER grant funds about 40 percent of the total project cost of the Southwest corridor, which is estimated at $43 million. The trail will ultimately include a bicycle and pedestrian transportation corridor which will connect to four schools and several parks.

The U.S. Department of Transportation awards TIGER grants to road, rail, transit and port projects that stand to have significant impact on a metropolitan area or region, according to the USDOT. Congress appropriated about $1.5 billion for the first round of TIGER funding. Now in its fifth round, the federal government awarded $474 million.

The Atlanta Beltline, begun in 2005, was one of 568 applicants from across the country for this round of federal dollars. The development project originally envisioned by Ryan Gravel aims to transform blighted land into a 22-mile loop of parks, trails and transit.