The opposition's spokesman on transport, Mark Parton, will move a motion in the Legislative Assembly calling on the government to make public its estimate for the completion of the project and how much the project will cost, to the nearest $100 million.

Mr Parton said Transport Minister Chris Steel and Chief Minister Andrew Barr were happy to be photographed with shovels but had refused to give the public simple details on the cost and timing of the project.

"This government has not even produced a business case for stage 2 but the Transport Minister has publicly stated they will build the tram regardless of what the business case states," Mr Parton said in a statement.

"It is not good enough for Labor and the Greens to continually spruik 'light rail is coming' to Woden but then refuse to tell Canberrans when the project will be completed or much it will cost taxpayers."

Mr Parton's motion, which is likely to be amended by Labor and the Greens when it is debated on Thursday, noted the first stage of light rail had a cost estimate, timeline and business case completed before the first works started.

Senate estimates was last month told work on stage 2A of light rail - linking the city to Commonwealth Park - would commence in January 2024, after work to raise London Circuit six metres is completed. The line is expected to be completed in January 2026.

Mr Steel has dismissed suggestions the project to Woden would not be completed for another eight years, saying federal funding expected to be transferred to the ACT in 2030 reflected the financial completion of the project.

But the ACT government has not said when the project is expected to be completed citing the procurement process currently underway for the project.

MORE A.C.T. POLITICS NEWS:

Canberra Liberals leader Elizabeth Lee on Tuesday declined to say whether her party supports the second stage of light rail in the ACT and later said in a parliamentary debate the project was a "Labor-Greens white elephant".

Ms Lee said she would have more to say on her party's position on light rail in the coming weeks.

An Auditor-General's report of the 2019 business case for stage 2A of light rail, a planned 1.7 kilometre link between the city centre with Commonwealth Park, found the case relied too heavily on so-called "transformational projects" around the transport corridor.

The audit found the business case failed to show how the line would be a catalyst for urban development, a key expected upside to the project.

However, the government has said the business case for the short link between the city and Commonwealth Park would not fully capture the intended benefits of the eventual link to Woden.

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