According to Infrastructure Partnership Australia, about $700 billion must be spent over the next 15 years to upgrade old key public infrastructure.

Australia currently spends about $60B.

To help raise infrastructure investment, The Wall Street Journal reports the coalition, should it win this year’s federal election, is thinking of boosting investor confidence in infrastructure projects by offering bond guarantees.

According to the paper, the party is hoping this will enable companies to raise more funds for major development projects more cheaply, by leveraging Australia’s top triple-A credit rating.

Under the plan, the Opposition is reportedly looking at creating special purpose bonds, backed by a government guarantee, allowing private companies to borrow at the same rate as the government.

“Separately, new government bonds with a maturity of up to 30 years would be issued to provide a price benchmark for the new infrastructure bonds,” a spokesman for shadow treasurer Joe Hockey told the paper.

“The longest term currently offered is 16 years.

“Tax rebates on infrastructure bonds are another option being considered.”

Sydney-based Citi economist Paul Brennan told the media outlet the proposal would benefit government and investors.

“A new 30-year bond would bring the Australia sovereign curve more into line with the world’s major government curves,” he reportedly said.

“For investors, it would offer an exposure to the highest grade of sovereign debt, without the extremely low interest rates offered by comparable sovereigns.”

The opposition’s announcement comes as government finances are under pressure from declining tax revenues, notably from the mining tax which failed to raise as much funds as expected by the federal government.

This pressure is being felt in the construction industry as government is noticeably withdrawing from public road and rail and building investment.

Another blow to the government’s finance was the repetition of natural disasters, particularly on the east coast, with floods affecting Queensland and bushfires impacting Victoria and New South Wales.

As the mining industry slows down, investing in major infrastructure projects may not only give old infrastructure a facelift, it would also facilitate contractors’ transition from the resources sector to civil construction.

The Opposition’s proposal could also help kickstart commercial construction, currently suffering from low investment.

Commercial construction is the weakest sub-sector of the construction industry, currently underperforming at 28.7 points (50 points indicates the start of growth), according to the latest Australian Industry Group of Performance Construction Index.