Four consortia submitted formal expressions of interest to the Capital Metro Agency for the public-private partnership last December and two of these, Canberra Metro and ACTivate will now go through the next stage of procurement, the request for proposal (RFP) stage.

Canberra Metro is led by Pacific Partnerships and includes Mitsubishi Corporation, Aberdeen Infrastructure Investments, John Holland, DB International Leighton Contractors, CAF, and Bank of Tokyo-Mitsubishi. ACTivate is led by Downer EDI and includes Plenary Group, Bombardier, Keolis, Parsons Brinckerhoff, Aurecon, Cox Architecture, Itochu, and Partners Group.

The capital cost of the 12km line from the city centre to Gungahlin is estimated at $A 610m ($A470m), with the government including an additional $A 173m contingency in its calculations.

The ACT government has asked the consortia to include costings for a 3.2km extension from Alinga Street to Russell in their bids.

ACT Capital Metro minister Mr Simon Corbell says the government expects to select a winning bidder early next year and construction will begin in 2016.