It is an idea that has been rolled out in election seasons for decades — but the New South Wales Government says its new plan to build a fast rail network is different to previous promises.

Key points: Glady Berejiklian denied the announcement was an election stunt

Glady Berejiklian denied the announcement was an election stunt The Government committed $4.6 million from the Snowy Hydro fund to develop the strategy

The Government committed $4.6 million from the Snowy Hydro fund to develop the strategy Opposition Leader Michael Daley says the pledge isn't feasible without Federal support

The Premier said unlike previous talk of light rail, the NSW Government was pushing ahead without the Commonwealth or the other states.

"I'm not going to wait for the other states and the Federal Government, we've waited too long so NSW will start the process," Gladys Berejiklian said.

But she refused to say whether the project would be dependent on federal funding.

The State Government has identified four potential fast rail routes to and from Sydney that it says could slash journey times by up to 75 per cent:

Northern route — including the Central Coast and Newcastle

Northern route — including the Central Coast and Newcastle Southern Inland route — including Goulburn and Canberra

Southern Inland route — including Goulburn and Canberra Western route — including Lithgow, Bathurst and Orange/Parkes

Western route — including Lithgow, Bathurst and Orange/Parkes Southern Coastal route — including Wollongong and Nowra

The Government said it will start work on the project next term if it is re-elected and it has asked international high-speed rail expert Professor Andrew McNaughton to chair a panel to confirm the most appropriate routes, train speeds and station locations.

Ms Berejiklian said the plan will make it feasible for more people to live in regional centres and commute to Sydney for work, which would also take pressure off the growing Harbour City.

"This is about giving our citizens, now and into the future, the choices about where they want to live, where they want to work," Ms Berejiklian said.

Professor Andrew McNaughton warned the fastest rail technology may not be feasible in NSW. ( Supplied )

She denied the announcement was an election stunt, but conceded it might take many years for a high-speed rail network to be built.

Ms Berejiklian said instead, the first stage might be faster rail — where trains would travel up to 200 kilometres an hour and new rail corridors may not be needed.

"I would envisage that in parts of routes we've identified you would rely on the existing corridor and upgrade or convert it to a faster rail," she said.

"Let's see what Professor McNaughton finds in terms of the stages and what is needed, but New South Wales … has the resources to really kick this along."

The Government has committed $4.6 million from the Snowy Hydro fund to develop the strategy.

Professor McNaughton warned the fastest rail technology is very expensive and might not pay off in NSW.

"I'm usually asked how fast is fast and the answer is as fast as is necessary to get the effects that we want," he said.

"Not as fast as is possible, because that's a vanity project — we're going to do as fast as what is necessary."

Labor leader Michael Daley said the Government's pledge is a desperate stunt.

He said the Government's plan is unrealistic because building high-speed rail is a mega task requiring federal funding and national cooperation.

"The NSW Liberals are now going into the comedy business," Mr Daley said.

"They want us to believe that they can do a fast-rail network in the next term of government.

"Absolute pie in the sky stuff."