A multi-billion investment programme aimed at getting Britain's economy moving is set to be announced.
Most of the money is expected to come from the big British pension funds, as well as Chinese investment.
However, £5bn will be paid for by further cuts in the present spending round.
Various road schemes around Britain and rail lines in Newcastle and between Manchester and Leeds are thought to be among 40 projects earmarked for help.
It comes ahead of Tuesday's autumn statement in which Chancellor George Osborne will outline spending plans.
The government says the initiative, called the National Infrastructure Plan, would see it and private investors support both social and economic schemes over the coming decade .
The Treasury hopes two-thirds of the £30bn earmarked for infrastructure schemes will come from the National Association of Pension Funds and the Pension Protection Fund.
The remaining £10bn from taxpayers would come from savings in current spending, the government said, although it is not clear where those savings would be found.
BBC business editor Robert Peston said only £5bn of this would be spent in the next two or three years, adding that £25bn of the allocated money "won't be available for years".
Our correspondent said the move to aid investment in major infrastructure projects was "important for improving the productive potential of the British economy, making it more competitive".
TUC's 'Plan B'
The 40 highlighted projects for support from the plan include the TransPennine Express line between Leeds and Manchester, the Metro system in Tyne and Wear as well as improvements to the M25, M3 and M56.
Meanwhile the TUC has issued its own plan aimed at reinvigorating the UK's economy.
It has called for a number of measures including cutting VAT, reversing the public sector wage freeze and giving a one-off increase in child benefits before Christmas.
It said its proposals could be implemented in the next six months.
TUC general secretary Brendan Barber urged the government to "change course" and introduce "immediate measures to support jobs and promote growth".
"The chancellor's economic plan A has sent unemployment to a 17-year high and the UK's economic outlook is the gloomiest it's been since the end of the recession," said Mr Barber.