Port of Tauranga is holding up its inland port at Onehunga as part of the answer to avoiding further reclamation of the Waitemata Harbour for port business.
Each day, up to six freight trains carrying 106 containers make the 224km journey from Ports of Tauranga to MetroPort, located at the industrial epicentre of Auckland.
In the past year, 180,000 containers were handled at the inland site - at prices competitive with what Ports of Auckland would charge, says Port of Tauranga commercial manager Graeme Marshall.
This month, the port company announced it had spent $37.2 million acquiring a further 6.8ha next to its MetroPort operation, which chief executive Mark Cairns said would be key to expanding access to and from international markets for Auckland.
The area of industrial land is almost the same size as Ports of Auckland's latest plans to extend Bledisloe Wharf into the harbour.
Mr Marshall said it was important to have a conversation about whether the money being considered for investment in Auckland would be better spent on an improved rail corridor to give better distribution in and out of the Auckland market.
The company believes that with some "relatively minor expenditure", up to 15 trains a day carrying 150 containers could travel between Tauranga and Auckland - about 820,000 containers a year.
In a series on port expansion this month, Port of Tauranga corporate services manager Sara Lunam said Tauranga could handle 100 per cent of the container growth Auckland is planning for, plus its own growth in the foreseeable future.
She was responding to an email from a concerned Aucklander, Michael Cooper, who said the Tauranga company was aware of the plans by Ports of Auckland to expand into the "stunning Waitemata Harbour".
Mr Cooper said his family had a long association with the Waitemata Harbour - his parents grew up in St Heliers, where he learned to sail. He and his wife swim every day at St Heliers through the summer.
"Reclamation is a no-brainer from so many points of view, particularly when the options on offer from Port of Tauranga and Marsden Pt are analysed," Mr Cooper said.
Ports of Auckland head of communications Matt Ball said there was no need for Tauranga to worry about taking Auckland's container growth.
"We've got plenty of room for it."
Ports of Auckland has a 15ha inland freight hub at Wiri that allows customers to drop off and pick up their cargo there instead of trucking it through central Auckland.