The ACT government appears unmoved by calls from a Legislative Assembly committee for the release of a second expert review of the light rail project's final business case by the end of the year.
The Legislative Assembly's cross-party budget estimates committee made a series of recommendations related to the $783 million light rail line linking the city and Gungahlin, restating calls for the release of a second independent review of the business case.
It called for the government-commissioned report to be released before the last sitting day for 2015, in November, citing "considerable political and community debate" on the cost-benefit analysis and on modelling assumptions.
"If the second review of the full business case can add to that debate, then it should be released," the committee report said.
Capital Metro Minister Simon Corbell won't say when the review – understood to be by an overseas expert – will be released.
He told the committee in June the government may release the review but would only do so "at a time of our choosing".
In April, the first review found the project's accurate benefit-cost ratio would not be confirmed until bids were received from two private consortiums.
The report by former South Australian Transport Authority head Derek Scrafton, now a transport planning expert at the University of South Australia, said the document was "fit for purpose" and made realistic conclusions about the tram line.
The government released Professor Scrafton's report on the same day as heated criticism of the project from academics at the Australian National University and the University of Canberra was reported in The Australian Financial Review.
Mr Corbell would not explain why he had refused to release the other review.
A spokesman last week restated plans for the other report to be released in "due course".
In April, Mr Corbell said the second government-commissioned review of the business case "concurred with the overall conclusions of Professor Scrafton".
"It stated that the overall benefits of the project could be higher than what was presented in the business case."
Chief Minister Andrew Barr will present the government's response to the estimates committee report in the Assembly on Tuesday.
The committee also called on the government to reconsider the choice of Eucalyptus mannifera, also known as brittle gum, as the replacement tree species for Northbourne Avenue.
Noting the tree was also referred to as a "widow maker", the committee's report said Mr Corbell had advised that all eucalyptus species could drop branches unexpectedly.
It also called for a staged replacement of trees to minimise the visual impact of cutting down trees along the route.
The spokesman said the two consortiums bidding to construct and operate the 12-kilometre line "have been told to create a grand boulevard using the eucalyptus mannifera".
The species has also been endorsed by the National Capital Authority.
"The ACT government has asked the Capital Metro Agency to explore the possibility of phasing the removal and replanting of trees along Northbourne Avenue during construction," the spokesman said.
Currently, about 480 trees line Northbourne Avenue and the Federal Highway median strips.
A 2014 assessment of the corridor trees found only 59 per cent were healthy.
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