US Secretary of Transportation Elaine Chao and Maryland Governor Larry Hogan applauded the public-private partnership that is being used to build a rail project in the Greater Washington area.

The US Department of Transportation's Federal Transit Administration on Monday announced a $900 million federal grant agreement for the Maryland Purple Line.

The 26-kilometer line will have 21 stations and be completed in 2022 and will improve access for thousands of Maryland residents to major businesses and activity centers in the state's most populated counties, according to USDOT.

"The Purple Line is a great example of what can be achieved when federal, state and private partners work together," Chao said at a funding-singing and groundbreaking ceremony on Monday in Hyattsville, Maryland.

She described the public-private partnership as holding "great potential for revitalizing our infrastructure and demonstrates how communities' projects can benefit through access to additional funding resources which can accelerate project delivery and provide greater innovation".

Hogan called the project the largest public-private partnership ever undertaken in the US, and said it "will be an important economic driver for Maryland".

"This multibillion dollar infrastructure project is a big win for the State of Maryland, and will be a major benefit to the National Capital Region. It is a shining example of what can be accomplished when our federal, state, county, and private sector partners work together," he said.

After the speeches, Hogan drove an excavator to bulldoze a building to make way for what will become the line's operations center.

The line, though not part of the Washington DC Metro system, will connect Metro, MARC and Amtrak. The total construction cost is about $2 billion, and the cost to design, build and operate the line is estimated at about $5.6 billion.

"It will integrate seamlessly with our current transit systems, combining Metro and Amtrak, to provide more transit options across the region. Just the construction alone will mean thousands of new jobs for Marylanders," Hogan said.

US President Donald Trump has promoted public-private partnerships as part of his $1 trillion infrastructure plan. He has proposed an incentive program in which the federal government provides up to $200 billion to state and local governments that enter into the partnerships.

While the method is often practiced in other industrialized nations, it is relatively new in the United States. Public-private partnerships accounted for just 1 percent of spending between 1989 and 2011 on toll roads, where the agreements are used most, according to a report by the Congressional Budget Office.

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