The price tag for building a 13-kilometre stretch of light rail from north Canberra into the city could be up to $860 million, according to a new transport study released by the ACT government.
But the announcement sparked a flurry of conflicting claims yesterday about the cost of the project, with light-rail proponents accusing the government of overstating the price.
The ACT Greens said the figure was as much as three times the price of light-rail networks in other cities, a claim disputed by Environment and Sustainable Development Minister Simon Corbell.
Mr Corbell said constructing light rail from Gungahlin to Civic would cost $700-$860 million, while bus rapid transit could be installed for $300-360 million. But he gave no guarantee the government would commit to either option before the October election.
The transport study also included figures showing bus rapid transit on the corridor would cut morning peak hour delays from 16 minutes to eight, while light rail would reduce delays to six minutes.
Mr Corbell said the costs would become clearer as more detailed analysis was done. The next stage of the project was asking Canberrans which option they preferred.
''These are large-scale projects and we must make sure we do the detailed investigation before we make the decision,'' he said.
Mr Corbell refused to speculate about which path the government would take but said ''doing nothing on this corridor is not an option''.
''I think it is the case that we need to commission further detailed investigations, including investigation of finance options, before we take a final decision on the transport technology,'' he said.
The $700-$860 million price tag puts the cost per kilometre to build light rail at approximately $54-$66 million.
The ACT Greens said figures from a West Australian feasibility study for light rail showed the cost per kilometre of installing light rail on the Gold Coast was $18-$22 million and in Sydney it was $15 million.
Greens Transport spokeswoman Amanda Bresnan said the government needed to hurry up and make a decision about public transport for the main commuter corridor.
''My key concern is we've got another announcement before an election, which happened in previous election years, but we still don't have an actual commitment to pursue public transport,'' she said.
ACT Light Rail chair Damien Haas said the rails would need to be ''plated in gold'' for the government's estimates to be accurate.
But Mr Corbell said the total cost of constructing light rail on the Gold Coast was $949 million, or about $73 million a kilometre, making the government's estimates comparable to that project.
''A brand new light-rail project should not be compared with an extension to an existing system in which vehicles and depots do not need to be purchased, as these items make up a significant proportion of costs,'' he said.
''The Gold Coast light rail is a current and comparable project, and the cost estimates are within a very similar range to the final Gold Coast project.''
Opposition Leader Zed Seselja said the government's ''inability to build things won't change anytime soon''.
''You can tell it's an election year because ACT Labor is once again making noise about light rail without any substance or action,'' Mr Seselja said.