Sydney's F6 extension puts historic railway, parkland and homes in firing line

But directors of the Sydney Tram Museum fear a planned extension of the F6 motorway between Sydney and the Illawarra will threaten the railway that dates back to the 1880s.

"It's the old [Roads and Maritime Services] trying to bulldoze things again," museum director Greg Sutherland said. "As an operating museum we depend on our tracks, and riding the tram to the national park is one of the great attractions for visitors."

Trams more than a century old carry passengers from the museum at Loftus on the western edge of the national park for 3 kilometres to near Bungoona lookout, which offers spectacular views of the area.

While talked about for decades, the prospect of a 37-kilometre extension of the F6 cutting through the historic railway, homes, wetlands and parks between Waterfall in the Sutherland Shire and Arncliffe in Sydney's south is quickly becoming real for the likes of San Souci resident Cheryl Abigail.

Mrs Abigail, who was born in the house she now owns near the Georges River, said an extension would result in significant relocation of homeowners and likely lead to protests from people concerned about its impact on nearby wetlands.

"We have always known it was going to happen but this time it seems like it actually is," she said. "I am probably not accepting of it but I'm of the principle of 'what can I do about it'?"

Until now, many have seemed unperturbed about what lay ahead. A house across the road from Mrs Abigail's home recently sold for $1.5 million.

Neighbour Spiro Roumeliotis accepts that the new road will one day force his family to leave because they knew about the F6 when they bought their four-bedroom home 16 years ago.

"It seems a lot closer than it ever has before," he said.

Fairfax Media revealed this week that the government has been considering buying 60 hectares of the Royal National Park or acquiring about 460 houses and 40 commercial properties between Loftus and Waterfall for the extension.

While one minister has suggested the National Park's size could be maintained by acquiring bushland elsewhere if the F6 encroached on park land, Premier Gladys Berejiklian said on Friday that the government would "never ever, ever, damage that precious heritage national park".

While her comments suggest homes or businesses at the southern end of the corridor will need to be acquired instead, Ms Berejiklian said it was too early in the planning process to say how many property owners were likely to be affected by an extension.

However, internal government documents have indicated that construction of the motorway, which will inevitably be tolled, could start as early as 2019.

And Ms Berejiklian said a number of major infrastructure projects would be nearing the end of their construction by 2018 or 2019, allowing the government to "ramp up construction on new projects".

The government will allocate an extra $15 million in the state budget next Tuesday for planning work on the F6.

A spokesman for Roads Minister Melinda Pavy also said no decision about the final alignment or form of the proposed F6 extension had been made, and the tram museum and other stakeholders would be consulted.

For proponents, an extension of the F6 has been seen as crucial to helping complete Sydney's motorway network.

At present, through-traffic between Sydney and the Illawarra is funnelled onto local roads, resulting in some of NSW's slowest peak hour speeds on the Princes Highway.

NRMA president Kyle Loades said congestion on the road corridor from southern Sydney to the Illawarra was worsening every year.

"There are more than 20,000 commuters and motorists daily who travel north for work and that will only increase over the coming decade or so as the population increases," he said.

Mr Loades said an extension would allow motorists to skip 60 sets of lights from Loftus to St Peters, and help remove trucks from suburban roads.

"The NRMA has been calling for this road for almost half a century. It would be good to see the government get on board with building it."

Government data shows average daily traffic volumes between Waterfall and Sydney's inner south have risen by 11 per cent to almost 57,000 over the past decade.

The potential impact on the national park and wetlands loom among the chief concerns.

National Parks Association NSW president Kevin Evans said the government had shown it was willing to allow infrastructure to trump nature.

"We can't continue to compromise nature the way we are," he said. "We need to find alternative ways to ensure that major projects and infrastructure can occur without doing any harm to these wonderful natural heritage areas."

And he described as an absurdity suggestions that land could be acquired to ensure the national park's size was maintained if the F6 encroached on park land.

"It is not like there is constantly land being made available to add to the national park," he said. "Nature is under attack by this government all over the state."

The Total Environment Centre said an F6 extension also threatened sporting fields used by thousands of people and waterways.

"Proponents will argue the F6 corridor has been on the books for years, but that hasn't stopped them demolishing the green grid that was also on the books," the centre's executive director Jeff Angel said.

"Sydney has had enough and they can expect a massive campaign."