Cronulla MP Mark Speakman says he would expect the state government to avoid unnecessary mass acquisition of homes and businesses for the F6 extension.
Mr Speakman, who is also the Attorney-General, was responding to Fairfax Media reports of internal government documents on the project.
One document said 60 hectares of the Royal National Park would need to be acquired.
The alternative, according to the document, would be the acquisition and bulldozing of about 460 houses and 40 commercial properties between Loftus and Waterfall.
Mr Speakman also downplayed the impact of ventilation stacks from road tunnels.
Fairfax Media revealed a draft government document produced in late 2016 had identified six locations for ventilation stations, exhaust stacks and air intake pipes in Arncliffe, Rockdale, Sans Souci, Kogarah and Miranda.
The F6 reservation, which at present is parkland, next to Port Hacking High School, is among the locations.
Mr Speakman said traffic was getting worse each year in southern Sydney.
“Public transport is very important especially for travel to and from major hubs, but it can’t get everyone efficiently to and from where they want to go especially outside hubs,” he said.
“The F6 is therefore an important missing link in southern Sydney’s transport infrastructure, yet the previous Labor government cancelled the F6 project.
“The Berejiklian government is getting on with extensive analysis to make sure a huge decision like the F6 is not made ‘back of the envelope’, but is properly costed and takes into account all economic, social and environmental impacts.”
Mr Speakman said options for the F6 were “being examined in detail”.
“No decisions have been made yet about, for example, whether to build an F6 extension and if so from where to where, location of entry/exit points along the way, underground versus overground versus a combination of both, and location of ventilation stacks if any,” he said.
“I expect a decision on the preferred configuration in 6-12 months.
“There will be extensive community consultation and environmental impact studies after that, before any final decision and commitment to build anything.”
Mr Speakman said ventilation stacks would be needed if any part of the F6 was underground.
“Modern ventilation stacks like those for NorthConnex have only a negligible impact on air quality around them,” he said.
“There have been dotted lines on maps for 70 years showing a proposed F6 corridor along the western boundary of the Royal National Park next to the main railway line.
“It’s astonishing that Labor politicians have suddenly woken up and discovered this.
“It only became part of the park when the former Labor member for Miranda said that the F6 would be built “over [his] dead body” and Bob Carr cancelled the F6 project.
“It’s now less than 0.5 per cent of the park and, if there’s a need to use any part of that old corridor, I would insist that it be replaced with additions to the park that more than adequately compensate.
“I expect that the government would avoid unnecessary mass acquisition of private homes and businesses.”