Promoters of public-private partnerships (PPPs) in New Zealand say the structures of prominent project failures in Australia are not being contemplated here.

Commentators in Australia are warning that investors have been turned off by the collapse of the Lane Cove Tunnel project in Sydney, following the earlier collapse of the Cross City Tunnel project, and it may affect the ability of Australian governments to raise funds for public infrastructure.

PPPs are being contemplated in New Zealand, but mostly for so-called social infrastructure like prisons and schools, rather than for toll roads.

The failed toll road projects in Australia have been compared to other financial booms that have gone bust. Consortiums were allegedly chosen on the basis of upfront payments to government and were overly optimistic about traffic volume and valuations. Arguably roads and tunnels that provided organisers with large fees were built that were not needed

Stephen Selwood, chief executive of the New Zealand Council for Infrastructure Development, said there was almost no appetite for the sort of structure used for the Lane Cove Tunnel in New Zealand or even in Australia now.

Lane Cove was a demand-risk toll road. Consortiums effectively competed for the right to levy a toll with upfront payments to government in the structure of the bids. The structure arguably incentivised bullish behaviour on the part of the private sector.

Toll roads were still possible in New Zealand and one was being considered for the Tauranga Eastern Motorway.

But the model of the Government levying the toll and taking the risk on traffic demand was more likely.

This was known as a service and availability PPP model.

"The private sector carries the risk for construction, operation and maintenance of the road and is paid for the provision of that service and gets its return over time in the form of service payments.

"The private sector still lends to the project, carries the risk on the project, and gets paid for delivering an open road if you like," he said.

He said the latest project in Australia, Peninsula Link in Melbourne, was a service and availability PPP with no toll.

He doubted that investors would be put off by the project failures in Australia.

"Most investors in these sorts of schemes are sophisticated investors and they will be knowledgeable of the various models.

"Superannuation organisations are looking for this type of investment. Where it might impact is if they were to issue a public bond or shares," he said.

In New Zealand, HRL Morrison and Co has formed the Morrison&Co Public Infrastructure Partnership Fund (PIP) to help build social infrastructure assets in New Zealand. It has ruled out toll roads.

The fund did not want to comment today but it has engaged Craigs Investment Partners to investigate the establishment of a retail fund to invest in the PIP fund.

The Guardians of New Zealand Superannuation are the cornerstone investor in the PIP fund, with a $100 million investment. Institutions are also expected to invest in the fund.

Mr Selwood said prisons and schools were being considered for public private sector partnerships here.

"Nothing has gone seriously to market, even including the prison. It is still every much in scoping. But our expectation is that the PPP market will begin in New Zealand in the social infrastructure area.

"We'd expect something this year," he said.