A second Auckland harbour crossing has been announced today by Prime Minister Chris Hipkins and Transport Minister David Parker.

Two new three lane road tunnels under the Waitemata Harbour, one going in each direction, and a separate light rail tunnel that will link to the existing Auckland Light Rail corridor is the proposed plan for the second Auckland harbour crossing.

The twin road tunnels would not be contingent on the light rail tunnels, with phasing options for the road tunnels to be considered by Waka Kotahi NZ Transport Agency, including whether to build both tunnels at once or separately.

In either case, additional busway, driving and cycling and walking capacity will be created at each stage.

Separately, a future light rail tunnel is proposed from the Wynyard Quarter, under the harbour east of the Auckland Harbour Bridge, and on to six new stations on the North Shore.

This too would be phased. Construction would not be expected to begin until after at least the first of the two road tunnels is completed.

Cross section of the harbour crossing. Image: Supplied.

“This is a bold plan for Auckland’s future that delivers a modern transport network that will connect all parts of the city,” says Hipkins.

 “Reducing congestion requires improvements to both roading and public transport, giving the public choice.     

 “Under this proposal the network will become joined up, allowing Aucklanders to travel from the north to the south, east and west on public transport - freeing up room on the existing Harbour Bridge and in the new road tunnel for those who want to drive.

 “A second harbour crossing is needed as soon as possible, and construction is planned to start by the end of this decade and why we are proposing a phased approach, ensuring additional capacity is achieved after each stage."

Hipkins says the recent wind-related bridge closures of the Harbour Bridge, and the increasing frequency of flooding on the approaches north of the bridge, illustrate the city’s vulnerability to interruptions.

"These new tunnels future-proof the city’s transport network by reducing reliance on the Harbour Bridge while creating fast new options for getting in and out of the city.

“A project such as this must be delivered in stages, like the Waikato Expressway was, so that the cost and roll-out of each element can be managed carefully and responsibly."

The Government has asked the New Zealand Transport Agency - Waka Kotahi to accelerate work on essential first steps towards realising a transport plan of this scale.

“We could afford the Harbour Bridge in 1959, when Auckland’s population was only 430,000, so we can afford a second crossing that will modernise transport for the city’s residents and the millions of people who visit every year."

The proposed benefits of a crossing. Image: Supplied.

David Parker welcomes another key element of the preferred option, extending the Northern Busway across the bridge into the city centre.

“The Northern Busway is among New Zealand’s most successful public transport projects – it has vastly improved the daily commute made by thousands of North Shore residents into the city centre each day," says Parker.

"Without it the northern motorway and the bridge would already be completely clogged at peak times.

“The twin-tunnel connection would allow the busway to be extended across dedicated lanes on the Harbour Bridge into the CBD. This is essential to maximising the value of other important investments such as City Rail Link currently under construction"

Parker says the Government is instructing Waka Kotahi to speed up work to protect the route and acquire land along the emerging preferred option corridors.

“The Waka Kotahi recommended option also includes raising State Highway One north of the Harbour Bridge to protect it from flooding caused by storm surges and sea level rise."

The emerging preferred option. Image: Supplied.

Parker says in his opinion, one of the problems in Auckland transport planning has been too much uncertainty.

"All harbour crossing options land in the same area south of the bridge, near to Victoria Park. This is the anchor point for everything.

“It is clear to me that the critical connections between the new tunnels, the Auckland Harbour Bridge, SH1 (south and north), SH16 (to the port and to the west), the City Rail Link, the Northern Busway, the much needed North Western busway, and any light rail options should be secured now."

Parker says much of the land is already owned by the Crown.

"Securing remaining land is important for all future options. The draft Government Policy Statement of Transport to be released in the coming weeks will prioritise and fund this.

“Waka Kotahi will also report back to Cabinet next year with a detailed plan for how the elements of the cross harbour plans can be phased and funded.

“With a project of this scale we will need to keep an open mind to funding options. We are seeking advice from Waka Kotahi on this."

Breakdown of the indicative costs of the constituent parts of the project:

• Indicative cost of road tunnels: $12-15 billion
• Indicative cost of SH1 improvements: $1.0-1.5 billion
• Indicative cost of Northern Busway upgrades: $0.5 billion
• Indicative cost of walking and cycling improvements: $0.5 billion
• Indicative cost of light rail tunnel (CBD to North Shore): $8.5-11 billion
• Indicative cost of light rail tunnel (North Shore to Albany): $12.5-16 billion
• Indicative overall cost: $35-45 billion