Costings released by shadow treasurer Joe Hockey and opposition finance spokesman Andrew Robb on Thursday reveal the Coalition will spend $2.56 billion on projects to duplicate the Pacific Highway by 2017 – the same amount as Labor has budgeted for.

But the Coalition is promising to finish the job "years" ahead of Labor because it says it will eventually contribute $5.6 billion to the highway. The bulk of that money, it emerged on Thursday, will not be paid until later in the decade.

The Coalition's costings also confirm its position of refusing to pay for urban public transport projects.

Major rail projects in Brisbane, Melbourne and Perth are likely to be delayed for years or mothballed because of this insistence, but it will have little immediate impact in Sydney where Labor has been unable to successfully fund a public transport project.

NSW Roads Minister Duncan Gay has said the Pacific Highway – 669 kilometres of road from Newcastle to the Queensland border – will be turned into a dual multi-lane divided highway "seven years" earlier under a federal Coalition government.

Mr Gay said last week the entire highway was likely to be duplicated by about 2020. Governments had previously aimed to complete the project by 2016.

Deputy Prime Minister Anthony Albanese said the funding represented a cut because it would allow the state government to drop its funding for the highway to 20 per cent of the federal funding.

"After years of rhetoric on the Pacific Highway, all the Nationals have come up with is a $2 billion cut to the Pacific Highway, which will put the full duplication into the never-never," Mr Albanese said.

A spokesman for federal Nationals leader Warren Truss confirmed the Coalition's target of finishing the project "within the decade", which is when the $5.6 billion in funding would be paid.

The spokesman said the federal Coalition would contribute an extra $1 billion a year in each of the 2017-18 and 2018-19 financial years.