As road links between Sydney and the Central West remain uncertain, a bold new suggestion has been put forward - a southern route through the Blue Mountains.

Margaret Bollingmoore and Roz Townsend say the time for politicians to consider a new route from Sydney is long overdue and the community needs to band together, generate ideas and force the government to act.

The topic has been back in the news after Bathurst transport stalwart Graeme Burke said last week that the closure of Bells Line of Road (which has since reopened in a limited capacity) needed an immediate response from the State Government to build a third route between Sydney and the state's west.

Ms Bollingmoore suggested the government look at a southern route going from Oakdale, west of Camden, to Oberon over the back of Yerranderie above the catchment area.

Ms Townsend said the suggestion had a lot going for it.

"It could be a great tourist attraction and would save the heritage villages in the [Blue] Mountains - it would also make it easier for people to get to Canberra, the South Coast and the new airport from this part of the world," she said.

She said the recent closure of Bells Line of Road highlighted the need for immediate action from the government.

"We need bold new ideas that create greater access and respect our heritage," she said.

Both women said a creative and lateral approach to roads west of Sydney is required.

"Focusing on upgrades to the two current options is not improving traffic flow and has resulted in slower journeys and the inability of large trucks to cross the Blue Mountains easily," they said.

"The Bells Line of Road is winding, mostly single lane, with limited overtaking spots, which can severely reduce traffic efficiency.

"[They are] surely not efficient for the major roads to the west."

They said the current routes service northern and central-western Sydney, with nothing for the south-western end and points south, which are the most rapidly expanding parts of Sydney.

"This proposal would remove the need for traffic heading to the south and south west to go near the new airport," they said.

In terms of the specifics of their proposal, they propose using existing roads to Nattai - the M5 Camden exit or Northern Road from Badgerys Creek, Narellan Road (M5 to Narellan), Camden Bypass, Old Hume Highway (turn into Burragorang) and Burragorang Road to Nattai.

Their proposed roads include a bridge over Warragamba Dam, a sky bridge past the escarpment and off-ramp to Yerranderie (which they said could also have tourism potential).

They are proposing a sky bridge past Kanangra Walls (with viewing platforms), off-ramp to Jenolan Caves (again, promoting tourism), and an upgrade to the road to Jaunter and duplication of Abercrombie Road to Black Springs.

They say the western options include to Oberon, then to the O'Connell Road to Bathurst and then Kings Plains to get to Blayney or Orange, and to Bathurst via O'Connell using Beaconsfield Road and O'Connell roads, with road upgrades required.

Both said there were many benefits to the proposal.

"There is easy access for freight between the Central West and Melbourne, Canberra, Badgerys Creek, Wollongong and the South Coast, with no need to go through Sydney," they said.

"It also allows avoidance of the Northern Road, for south- heading traffic. It provides tourist opportunities and a far more direct route, saving travelling time and faster speeds."

They said the roads that need upgrading under the proposal would benefit anyway.

Both Ms Townsend and Ms Bollingmoore said the proposal could be a private/public development attracting a toll, which they said most would consider acceptable if travel time was reduced.

"It also opens up additional areas south west of Sydney to further development by providing infrastructure," they said.

The pair said they had considered the need to mitigate damage to Sydney's water supply, but said this had been done successfully before in other areas.

They also conceded potential damage to the Blue Mountains National Park and Kanangra-Boyd National Park in opening up previously isolated areas.

Still, they said now was the time to put forward proposals for a third route.

"We need bold ideas and we need to move forward," Ms Townsend said.

"Western NSW businesses and residents should be able to travel to the state capital as most other areas of the state can do now."