A rendering of what a light-rail Purple Line train would look like running through the University of Maryland campus in College Park. (Maryland Department of Transportation)

A team of private companies recently awarded a $5.6 billion contract to design, build and operate a light-rail Purple Line in the Maryland suburbs has begun pre-construction work on the rail project, state officials said late Thursday.

The companies — a consortium called Purple Line Transit Partners — were granted “limited notice to proceed” shortly after state Transportation Secretary Pete K. Rahn signed the contract for a 36-year public-private partnership April 6, officials said.

Under the limited go-ahead, the team may complete the line’s design and do soil borings and survey work, said Charles Lattuca, head of project development and delivery for the Maryland Transit Administration. Lattuca and Rahn spoke Thursday night at a Purple Line forum in Silver Spring sponsored by the advocacy group Purple Line Now.

After the gathering, Lattuca said the pre-construction work will amount to $12 million, which the state likely will pay after the work is completed this summer. He said the state plans to grant the team full “notice to proceed,” which would allow construction to begin, soon after it signs a full funding agreement with the Federal Transit Administration for $900 million in anticipated federal construction grants. That agreement is expected to be signed in July. The bulldozers can’t rev up until that full permission is granted.

Lattuca said final design is expected to be completed in October, with construction beginning in November or December. Initial construction, which will start in Prince George’s County, will mostly entail moving underground utility lines, such as water or sewer pipes, Lattuca said.

Ralph Bennett, president of Purple Line Now’s board, told the group that a transportation official at the University of Maryland recently said state officials have told him rail construction will begin on the College Park campus in spring 2017.

The 16.2-mile light-rail line will run 135-foot single-vehicle trains along a recreational trail and local streets between Bethesda in Montgomery County and New Carrollton in Prince George’s County. The east-west line will connect Maryland’s Metrorail lines with Amtrak and MARC commuter rail stations and have 21 stops, including Silver Spring, Langley Park, the University of Maryland and Riverdale.

Lattuca told the audience of about 50 people that the state will open the entire line at once, rather than in stages, in spring 2022.

Another state official said construction can begin, even as a federal lawsuit opposing the rail project on environmental grounds is pending.