Thousands of documents were delivered to the ACT Legislative Assembly on Friday as the government accepted final bids from two consortiums for the $783 million light rail contract.
The submissions are the final roll of the dice for many international corporations with the ACT government expected to sign a contract in early 2016, with work to begin in following months.
But a series of workshops between Capital Metro representatives and the two bidders have prompted some opponents of light rail to question whether a final decision is closer than expected.
One of the consortiums bidding for the job, Activate, is understood to have 100 staff working from a Moore Street office in Canberra. The other, Canberra Metro, is working from an office in Sydney.
Canberra Metro is led by Leighton subsidiary Pacific Partnerships and includes Mitsubishi and John Holland, and German firm DB International GmbH
Activate is led by Downer EDI and includes train-building company Bombardier and Keolis Downer, which operates the new Gold Coast tram and Melbourne's tram network.
Capital Metro director Emma Thomas said the submission deadline was a significant milestone and representatives had met with both groups close to 80 times to discuss their bids.
"We have met with both participants roughly every fortnight in several types of meetings to talk about commercial requirements, landscapes, affordability and their aspirations," she said.
"The aim is to get the very best outcome for Canberra and the better they can understand what we need, then the better they can deliver and we can be sure we have the best we can get."
Both consortiums were required to submit detailed proposals for the 12-kilometre light rail track from Gungahlin to the city on Friday, with a further proposal for a 3.2-kilometre extension to Russell due in four weeks.
Ms Thomas said she wouldn't second guess government intentions but a decision on the winning bid would likely be made in early 2016.
"We will provide a recommendation to the government early next year but until we start a detailed evaluation we won't have an idea of a set date," she said.
Anti-light rail lobby group Can The Tram has questioned why 80 workshops were necessary and whether the government were tempted to sign a contract earlier than expected.
"The government has a major motivation to do this namely to allow the contractor to rack up as many cost commitments as possible before the 2016 election and make it harder for a Liberal government to cancel the contract," a spokesman said.
Opposition transport spokesman Alistair Coe raised concerns about the future of the project after the government reached a provisional agreement with the ACT Heritage Council to save 17 public housing buildings on Northbourne Avenue.
"If the government was banking on developing the entire Northbourne Avenue strip and now there is less land to develop, then that will reduce the value of the land use benefits claimed in the full business case," he said.
"Regardless of whether people like the public housing properties or not, the government was banking on redeveloping those sites and now they are not going to be able to."
In June, Opposition Leader Jeremy Hanson and Mr Coe wrote to the two consortiums warning they had called for contracts to be delayed until after the October 2016 election.
But Unions ACT secretary Alex White said a recent telephone campaign showed voters were able to see through "the misleading, partisan campaign run by the ACT Liberals".
Mr White said an automated telephone campaign in the Murrumbidgee electorate on Wednesday night asked residents to tell Mr Hanson they supported light rail.
"Almost everyone who received our call listened to the entire message, an incredibly strong outcome that shows that Canberrans want more information about light rail job creation," he said.
Ms Stone said Capital Metro was in the final stages of establishing business and community reference groups that would provide advice to the government and be a mediator for questions.
"To get to this stage has been a big effort from our team and all across the ACT government, it doesn't just stop at Capital Metro," she said.
"We are very appreciative of both our respondents as this is such a good thing for Canberra and they have really pulled together."