A government-commissioned working group has recommended relocating Auckland's port operations to Northport, near Whangarei, at a cost of $10 billion.
Of the five options considered, the full shift of freight operations to Northport had the strongest business case, offering a benefit-to-cost ratio of 2:1. The other options range from status quo, to moving parts or full operations to both or either of Northport or the Ports of Tauranga.
The independent working group has reported to Ministers that this move would reduce congestion in Auckland, promote resilience in the supply of goods to Auckland, and allow for a more valuable use of the 77 hectares the Ports of Auckland currently occupies on Auckland's waterfront.
It's the second interim report of the Upper North Island Supply Chain Strategy group. The Prime Minister and Associate Minister of Transport Shane Jones said a decision will be made once the final report is provided and considered.
"We haven't formed a view, and the final report has not been provided to the government. When it does, we'll consider it," Jacinda Ardern said.
But Mr Jones said the report's preference was evident.
"This report clearly outlines the direction of travel: the days of Auckland maintaing a port and continuing to encroach on the harbour, those days are over," Mr Jones said.
"This is the King Kong of infrastructure projects - nigh on $10-billion. It will take some time but it gives substance to our government's position that we are transformational. It's arguably the epic infrastructure project of my generation and future generations."
The report found keeping freight operations in Auckland would cost $9.5 billion, but this option also performs "very weakly" against the criteria, which examines 14 factors, ranging from economic, social, cultural and environmental impacts.
The strategy group, which is made up of six infrastructure, shipping and management experts, said the relocation to Northport would require "rejuvinating" the North Auckland rail line, which runs from Whangarei to South Auckland, and include a rail spur at Northport. It would also require a new inland freight hub in the northwest of Auckland.
Cruise lines would continue to dock in downtown Auckland. It also said the move could impove road safety by increasing freight transport by rail, and would also provide opportunities to develop Northland and the Bay of Plenty.
Mr Jones said the Ports of Auckland is struggling, and the city's affected as a result.
"The city is being terrorised by congestion with the Ports of Auckland. The city's balance sheet is being terrorised because the Ports of Auckland can't even pay a dividend, and it is losing business every week to Tauranga," Mr Jones said.
"The project, when I use the term King Kong, reflects the fact that it is collosal, it is epic, and it has the capacity to future-proof New Zealand's trading export relationship with the international shipping lines and the rest of the world."
A Colmar-Brunton poll found 55 percent of Aucklanders surveyed would prefer Auckland's cargo port is moved, 28 percent want to keep it where it is, and 17 percent aren't sure.
The final report by the group was due to Ministers in September, but Mr Jones said it has not yet been provided.
"When the report has been effectively dealt with by Cabinet ministers, I am absolutely confident everything will be available to the public, but first we must go through the process.
"This is a major, nation-building, transformational project, and I look forward to shepherding it through our processes as a coalition government with my cabinet colleagues."