This is a rendering of what a light-rail Purple Line train would look like running through the University of Maryland campus in College Park. (Courtesy of the Maryland Transit Administration)

Four teams of private companies submitted proposals to Maryland transit officials Tuesday detailing how much it would cost for them to design, build, operate and maintain a light-rail Purple Line and how much financing they would contribute toward the 16-mile line’s construction.

The details, which weren’t made public because they’re part of the state procurement process, came in the financial parts of the teams’ bids for a 35-year public-private partnership on the project. The financial proposals were due at noon Tuesday. The teams submitted the technical portion of their bids — how they would design, build, operate and maintain a Purple Line — in mid-November.

The Purple Line would connect Bethesda in Montgomery County with New Carrollton in Prince George’s County inside the Capital Beltway, with 21 stations. The line, which state officials have estimated to cost about $2.16 billion to build, would be designed to provide a rail connection between Maryland’s ends of the Metro system and MARC commuter and Amtrak stations.

Under the state’s plan, the Maryland Transit Administration would own the Purple Line and set fares, while private companies would design and build it over about five years, and then operate and maintain it over 30 years. The private team also would finance some of the construction costs. The state would pay off the private sector’s debt service costs over time and pay the private team monthly for operating and maintenance costs. The monthly payments also would include the private sector’s profit and could be reduced if certain performance standards — such as clean trains and reliable service — aren’t met, state officials have said.

The four consortiums of private companies bidding on the project are: Maryland Purple Line Partners, Maryland Transit Connectors, Purple Line Transit Partners and Purple Plus Alliance. Each team consists of multiple companies, including some of the world’s largest engineering and construction firms.

State officials have said they plan to begin negotiations with a preferred team by Jan. 15, and make the final selection in February. The state’s Board of Public Works, which approves major contracts, is scheduled to review it in March. If the state secures up to $900 million in federal grants, construction would begin in 2016, with trains running in 2021.