Transport Minister Simon Bridges has confirmed a rail option will be part of an alternative Waitemata Harbour crossing that he says will "future-proof" the proposal.



Bridges said the move was necessary because of the rapid growth in Auckland over the next 20 years.

The Transport Agency (NZTA) believes an additional crossing would cost $4 billion to $6 billion, and would be needed between 2025 and 2030. A construction start date will depend on a number of factors, including the rate of freight and traffic growth.

"I have asked the NZ Transport Agency to recommence work on what will be a critical transport link for Auckland and the upper North Island. The preferred route for the additional crossing is a tunnel east of the Auckland Harbour Bridge between the Esmonde Road interchange on the North Shore, and Victoria Park Tunnel and Central Motorway Junction in central Auckland," Bridges said.

Advisors were "preparing for the designation process and are putting together a business case focusing on the timing of construction and potential funding options.

In June 2013 Prime Minister John Key threw the Government's support behind a tunnel in preference to a bridge, but the process was subsequently stalled..

"This is all about future-proofing both Auckland and New Zealand as best we can," Key said at the time, putting a figure of $4.6 billion on the preferred six-lane road tunnel, with capacity for a future rail link.

Bridges said that with increasing demands on Auckland's transport network, the Government would continue to work closely with local government to provide a resilient network and wider transport choices.

The business case will look at a range of public transport options, including heavy rail. NZTA and Auckland Transport will be working together on this part of the project, including any necessary route protection for public transport.

"The Government knows that investment in all modes of transport will ease congestion and bring lasting benefits for Auckland and for New Zealand as a whole," Bridges said.