A New South Wales MP is calling for the duplication of a notoriously dangerous road linking Sydney's south-west to Wollongong using funds from the state's budget surplus.

Picton Road carries around 40,000 motorists a day, with 22 per cent of all users being freight trucks carrying loads to and from ships at Port Kembla — the largest vehicle import hub in Australia and the state's primary coal cargo facility.

But the road is expected to come under unprecedented pressure as more than 16,000 new homes are constructed to the west and freight volumes in and out of Port Kembla continue to grow.

Wollondilly MP Jai Rowell is calling on his own Government to start planning now for its duplication.

"In the future, with Wilton Junction becoming the fifth largest regional town in NSW — at the moment it's a paddock — if we don't go ahead with the duplication of Picton Road this region will become another M5 land-locking car park," Mr Rowell said.

"The Government is investing in the duplication of the M5, and that is much needed, but we'll just recreate those problems we currently have there locally," he said.

"We do have a surplus at a state level and I am calling on the Government to spend some of that surplus here in the Wollondilly and in the Southern Highlands."

The Wilton Junction project is progressing through the planning process with the first homes expected to be built next year.

The ABC understands duplicating Picton Road would cost NSW billions of dollars.

Mr Rowell says he intends to raise the issue in parliament imminently.

He acknowledged challenges in duplicating a major road through protected catchment lands which supplies water to millions of people in Sydney and the Illawarra.

"Nothing is impossible, and if we are going to take our fair share of growth which we are, and I am supportive of that, we need to take our fair share of infrastructure upgrades," he said.

Picton Road connects the outskirts of Sydney to Wollongong. ( Supplied: Ozroads )

No current plans to duplicate

NSW Roads and Maritime Services had previously raised the idea of duplication, according to Mr Rowell, but the Government agency would neither confirm nor deny if talks had taken place.

A spokesman said RMS "is developing short and long-term plans to further improve the safety and efficiency of Picton Road".

"Since 2009 the NSW and Federal Governments have spent more than $60 million aimed at improving safety and reducing crashes along Picton Road, including speed related and head-on crashes, crashes on a wet road surface, and crashes from vehicles running off the road," a statement read.

It is understood the RMS has discussed the potential for extra lanes on Picton Road to improve traffic flows and alleviate future congestion.

Despite the safety improvements along the 37-kilometre stretch, Picton Road has been the scene of at least 18 fatal accidents and 60 crashes involving serious injuries over the past decade.

"It is simply not enough with the volume of traffic that is starting to come that way," Mr Rowell said.

"These are band aid solutions to a real need that is on our doorstep.

"You can't expect this much growth without these types of upgrades and, of course, people need to travel to Wollongong to access work and employment.