All three parties in the Legislative Assembly agreed the bus connection between Belconnen and the city centre ought to be improved but none could agree on the wording of a motion that would compel the government to take action.
But the government said it would still put forward an updated case to fund the upgrades to the federal government despite the Assembly debate.
Jo Clay, the Greens' spokeswoman on public transport, moved a motion that would have called on the government to commit to investigating and delivering upgrades on the bus corridor within three years while also beginning early planning work for a light rail link from the city to Belconnen.
Transport Minister Chris Steel moved an amendment that would have dropped the commitment to deliver the upgrade and instead note any decision would be subject to budget consideration after an investigation.
Mark Parton, the Liberals' spokesman on transport, moved a separate amendment that included the commitment to the busway improvement while dropping any mention of future light rail stages, which the Canberra Liberals oppose.
After a lengthy debate on Wednesday afternoon, none of the three parties could agree with each other's amendments, which ensured Ms Clay's original motion was ultimately defeated.
"The Greens have sacrificed a better bus service for a ghost train," Mr Parton told The Canberra Times.
Ms Clay said ACT Labor and the Canberra Liberals were all talk and no action.
"This project has been in the pipeline since 2011. The time to commit is now," Ms Clay said in a statement.
"Belconnen deserves better, faster bus services and a dedicated lane. More than 30 per cent of boardings each weekday are on routes that use this corridor."
Ms Clay said the Greens could not betray the people of Belconnen by supporting the Liberals' amendment that was not prepared to "future proof" a Belconnen light rail link. "I'm incredibly disappointed with my ACT Labor colleagues and all MLAs in Ginninderra who voted against the Belconnen busway," she said.
Mr Steel said he supported the objective of Ms Clay's motion but did not support its method.
"If I could just snap my fingers and provide more bus priority between the city and Belconnen, then I would, but there's a process for delivering large-scale infrastructure projects with significant capital expenditure. It's more complicated than that. We need to undertake the investigation ... first," he said during the Assembly debate.
Mr Steel later said in a statement the government would move to put forward an updated feasibility study for the design of the Belconnen TransitWay to the Commonwealth in an effort to secure funding.
"ACT Labor supports the Belconnen TransitWay and the first step is undertaking an updated feasibility study to determine what remaining improvements can be made to the corridor that would make a difference to bus travel times," he said.
"The updated feasibility study will also consider other opportunities to improve active travel infrastructure, and connections between bus stops and key infrastructure - something the Greens and Liberals had not considered until proposed by ACT Labor."
