Spending on roads, rail and other major infrastructure will be fast-tracked under a new funding approach to be unveiled by the Turnbull Government in May's budget.

Key points: Government expected to fast-track infrastructure spending in budget

Government expected to fast-track infrastructure spending in budget It's also planning to take equity stakes in big infrastructure projects

It's also planning to take equity stakes in big infrastructure projects The Government is moving its focus away from housing affordability

The ABC's 7.30 program understands much of the $50 billion infrastructure plan from last year's budget is going to be brought forward.

7.30 can also reveal the Government is now intent on taking equity stakes in big infrastructure projects, including taking a share in tolls raised on roads part-funded by the Commonwealth.

It is understood the focus on infrastructure in the budget is in part due to the Government wanting to play down expectations it could fix the housing affordability crisis.

Taking its toll

Prime Minister Malcolm Turnbull is said to be keen on the Government taking equity stakes in big infrastructure projects. ( AAP: Dan Peled )

The Prime Minister has also grown weary of states taking credit for infrastructure projects part-funded by the Federal Government.

According to Cabinet sources, Malcolm Turnbull has regularly cited the Toowoomba Second-Range Crossing in south-east Queensland as a case in point.

The Federal Government put more than $1 billion into the project, which is 80 per cent of the total cost.

Yet when the road is finished in late 2018 the Queensland Government will likely claim much of the kudos.

The State Government will also be the beneficiary of a toll, with drivers paying up to $30 a vehicle to use the 41km link.

A rethink inside the Federal Government, led by Mr Turnbull, will see the Commonwealth adopting an approach that resists handing over money on major infrastructure projects without strings attached.

This will mean more loans instead of grants and it could see the Government assuming an interest in the second Sydney airport at Badgerys Creek.

The Federal Government will also demand a cut of any proposed tolls on roads it helps fund, as the Prime Minister has proposed to do with Melbourne's Western Distributor.

Good debt, bad debt

Treasurer Scott Morrison mentioned using "good debt" to pay for infrastructure. ( ABC News: Matt Roberts )

Treasurer Scott Morrison's speech about "good debt" and "bad debt" has helped lay the groundwork for a big infrastructure spend in the May 9 budget.

"It can be very wise for governments to borrow, especially while rates are low, to lock in longer term financing and invest in major growth producing infrastructure assets, such as transport or energy infrastructure," Mr Morrison said.

"But to rack up government debt to pay for welfare payments and other everyday expenses, is not a good idea."

Peter Newman, one of the Prime Minister's advisers on cities policy, said infrastructure projects did not always offer good debt, nor were they always popular.

"There's some very bad examples where Tony Abbott dropped big road projects on us that we didn't need. They were just designed to create jobs out of digging up places," Mr Newman said.

"I'd like to think that every bit of infrastructure needed to pay for itself, so why not make infrastructure funding from the Federal Government but based on a loan and therefore you get private development around it that helps to pay it back.

"That's a good way to do it because you're getting better cities at the same time as better infrastructure."

Next wave of growth

The Government is moving its focus away from housing. ( ABC News: Angela Ross )

Financial analyst Martin North said that after focusing on housing, the Government was looking to catch a more promising wave for growth.

"When the mining boom came off, essentially they were looking for the next wave of growth engines and effectively the one selected was households and household debt," Mr North said.

"You want to be investing in the future, you want to be investing in growth, because if you can get enough growth than you've got the ability to repay the debt.

"If you haven't got growth, what happens is the debt just goes down the generations and never gets paid off."