The Maryland Department of Transportation and Maryland Transit Administration have released detailed requirements for the four private concessionaire teams bidding to build and operate the Purple Line light rail.

The Purple Line Request for Proposals was issued Monday and must be submitted by Jan. 9, 2015. MDOT and the MTA will then select a preferred partner out of four teams on the shortlist by March 12.

The public-private partnership — which would include helping the state design, build, finance, operate and maintain the 16-mile system — would be for a 35-year contract term.

The selected private concessionaire team would be put before the Board of Public Works for approval in spring 2015 and, if approved, construction of the Purple Line would start later in 2015.

“This is a significant milestone towards construction of the Purple Line, which will help us grow our economy, create jobs for Maryland’s workers, and strengthen communities in Prince George’s and Montgomery counties,” Lt. Gov. and Democratic governor nominee Anthony Brown said in a statement. “Building the Purple Line as a public-private partnership will allow us to continue our commitment to fiscally responsible budgeting while using the knowledge and skills of the private sector to expand our transportation infrastructure.”

Whichever private concessionaire is picked is expected to finance $500 million to $900 million of the overall $2.37 billion project.