Four teams of private companies have been chosen to compete for a public-private partnership to design, build, operate, maintain and help finance construction of a $2.2-billion light-rail Purple Line in the Maryland suburbs, state officials said Wednesday.

The four were chosen out of six teams that submitted “statements of qualifications” in mid-December.

Maryland Department of Transportation officials said they plan to select a winning bid by early 2015. That would allow construction of a 16-mile line between Bethesda and New Carrollton to begin in spring 2015 and open in 2020, officials said. The line connecting Montgomery and Prince George’s counties would have 21 stations, including in Silver Spring, College Park, Langley Park and the Riverdale area.

A public-private partnership on a Purple Line would be the first for a Maryland transit project. Only one other U.S. transit project – in Denver — has such a far-reaching public-private agreement, which is still under construction.

Maryland officials said they will ask that private companies contribute $500 million to $900 million toward the line’s construction. Under a contract, which would span 35 to 40 years, the state would pay the team annually to operate and maintain the line based on certain performance standards.

The “short-listed” teams selected to submit bids are: Maryland Purple Line Partners, comprised of Vinci Concessions, Walsh Investors, InfraRed Capital Partners, Alstom Transport  and Keolis; Maryland Transit Connectors, comprised of John Laing, Kiewit Development and Edgemoor Infrastructure; Purple Line Transit Partners, comprised of Meridiam Infrastructure, Fluor Enterprises and Star America Fund; and Purple Plus Alliance, comprised of Macquarie Capital and Skanska Infrastructure Development.

Teams were judged on prior experience, personnel, organization, financing capacity and overall approach, officials said.

A Purple Line, which is seeking $900 million in highly competitive federal construction funding, would connect neighborhoods with Metrorail stations and Amtrak and MARC commuter rail stations. The state has allotted $750 million to the project.