South Australia's Infrastructure Minister admits he will not be surprised if costings for the North-South Corridor blowout beyond the $9.9 billion budgeted, but says he is yet to receive revised costings.
Tom Koutsantonis refused to confirm reports that the project cost would escalate to $14 billion, but a cost increase was already foreshadowed in this year's state budget.
Mr Koutsantonis said the Department for Infrastructure and Transport had not advised him of cost estimates since a project review was commissioned when the Labor government came into power in March.
But he took aim at the previous government's $9.9 billion estimate, saying designs were "deliberately left out to minimise costs" before the election.
He cited towering overpasses and one-lane exit lanes that would be unworkable and expensive to redesign and build.
"I'm not surprised it'll be more than $9.9 billion," he told ABC Radio Adelaide.
"But if we don't do something in that section between Anzac Highway and Tonsley, the grid between Goodwood Road and Marion Road will grind to a halt."
He said choke points along South Road on Richmond Road, Anzac Highway and James Congdon Drive are "urgent and need to be fixed".
The minister said reports that a cost-benefit analysis returning a ratio of less than one – meaning the costs outweigh the benefits of going ahead — was news to him.
Department for Infrastructure and Transport chief executive Jon Whelan said he did not have a specific figure on the project cost or an updated cost benefit ratio at this stage.
The cost of the Torrens to Darlington stage blew out from $8.9 billion to $9.9 billion under the former Liberal government while Mr Koutsantonis announced the project start would be delayed by a year to 2024, with the completion date set around 2031.
Final costings and a revised reference design will be available in weeks.
Opposition infrastructure spokesman Vincent Tarzia wants the government to "come clean" about what's causing the cost blowout, which he said was "scandalous".
"We haven't seen any facts to back up a $4 billion blowout," he said.
"We can't understand how this could potentially happen.
"All our information was that the project was locked and loaded, ready to go.
"It was signed off by independent bodies and you don't go and secure billions of dollars from the federal government unless it was ready to go."
More properties will be acquired
Mr Koutsantonis confirmed tunnels would remain part of the design on the section of the roads south of Anzac Highway and in the western suburbs areas.
"There will be tunnels, the question for us is the final design," he said.
"It'd be impossible to do a lowered roadway section through Thebarton, Torrensville and Mile End because of the historic landmarks there."
The minister said more properties would need to be acquired but some properties may be saved from the cut.
"But for the southern end, for Glandore all the way through to Tonsley, all those properties that had been identified to be acquired will still need to be acquired."
The infrastructure department chief executive said further investigation will be done on acquisitions required north of Anzac Highway.
Mr Whelan said they would avoid moving Hindmarsh cemetery
The department will do another community consultation after their analysis is submitted to cabinet.
