Transport officials have warned the government the Auckland Light Rail project is too big and too complex for any public agency to deliver.
Documents released to RNZ show Cabinet ministers want a public sector entity to oversee the major transport project.
But officials say if that's the case, expertise within an existing agency will need to be bolstered or an entirely new organisation will need to be established.
Auckland light rail came to a screeching halt at the end of the last parliamentary term because New Zealand First refused to support it.
Two project proposals received by the government from NZ Infra and the New Zealand Transport Agency were taken off the table and light rail was referred to the Ministry of Transport for further work.
A July briefing, released to RNZ under the Official Information Act, set out how the Ministry and Treasury plan to move the project forward, in order to advise the current government.
That advice will enable ministers to determine a course for the project over the next parliamentary term, it said.
The briefing stated that within the first six months of the government's formation, Cabinet will need to make arrangements for the delivery of the project, "including the nature of any decisions needed to enable the establishment of a delivery entity (or entities) and the roles of the key agencies".
Ministers will also need to look at funding options and creating a clear timeline on the delivery of the project.
The paper stated Cabinet wants Auckland light rail to be delivered by a public agency, but Ministry of Transport officials stated its view the project's size and complexity meant no existing agency had the ability.
"The capability and capacity demands of a project of this scale and complexity are almost unprecedented in New Zealand, and no current entity has the necessary capabilities to deliver the project. All options will be considered, including building expertise within an existing entity of establishing a new one," the briefing stated.
The risks of the projects design and construction and who can best manage that risk will need to be considered when deciding who is best placed to deliver light rail, officials said.
"Given the complexity of the project and its significant funding requirements, we anticipate that there will need to be robust governance and assurance to manage Crown risk, including a detailed approach to change management and contingency management," the paper said.
Transport officials explain how, without further funding, their work to progress the Auckland light rail project was likely to be delayed and their advice to the government will be "heavily scaled back".
The briefing stated that ministers had previously agreed in principle for the $4.64 million allocated to establish a Green Transport Card in the 2019 budget to be used instead on the Auckland light rail project.
In the July briefing, however, officials said because the project was dead in the water at the end of the last Parliamentary term only $1 million was needed.
It is not clear if the revised funding reallocation was signed off by the former Minister of Transport and Finance Minister.
'Bizarre process'
Public transport advocate Matt Lowrie, editor of transport blog Greater Auckland, said like the City Rail Link, it was a huge project needing experience and a separate entity would be needed to deliver that.
Looking at the documents, he told Morning Report it has been a "bizarre process" until now.
"We really need to see what's been proposed, where they are going to do and when they are going to do it; that's really the key."
He hoped the new agency would be accountable to the government, Auckland Council and Aucklanders.
"We should be able to do that," he said citing projects like Waterview in the past; but it was important to avoid being in a situation like the Transmission Gully.
"Having it under the government would make sense, and having it as a separate delivery agency would make a lot of sense as well."
Even if there was an agreement to move forward, he said it would take a few years to design and consent everything, before shovels are in the ground.