The government has chosen the partially-tunnelled option for the much-delayed Auckland light rail project.

Infrastructure minister Grant Robertson and transport minister Michael Wood, who was tasked with bringing the project back on track, announced the decision along with earlier construction of a second Waitematā Harbour crossing.

The second crossing will be brought forward to 2023 to align with light rail and new rapid transit to the North Shore and north-west of the country's largest city.

Auckland's population is projected to increase to 2 million by early next decade, Robertson said, requiring well-planned and connected infrastructure.

“We are not going to repeat the mistakes of ad hoc planning and a scramble to build infrastructure when it is too late – this rapid transit system is about making sure Auckland is able to flourish as it grows.”

Partially-tunnelled light rail was the preferred option of the Auckland Light Rail group, which unveiled three short-listed options last year.

According to advice released by the group, the project linking the city centre and the airport – which features a tunnel between Wynyard Quarter and Mt Roskill roughly following the route of Sandringham Rd rather than the above-ground option on Dominion Rd – had an estimated cost of $14.6 billion.

The street-running option favoured by groups like Greater Auckland, which would have run down Dominion Rd, was costed at $9b.

Light rail had the potential to double development in the rail corridor, enabling up to 66,000 homes by 2051.

The selected option would see transport available every five minutes from about 18 stops, cutting travel times between the CBD and the airport in half.

The press release from Robertson and Wood suggested the project could create up to 97,000 jobs. A business support package would be developed alongside affected businesses.

After surfacing at Mt Roskill, the light rail option chosen by the government would run alongside the SH20 motorway to the airport.

With the city rail link, Wood said the project would allow faster trip times and reduced emissions. Light rail would form the spine of a new fully integrated transport network, he said.

“Addressing future disruption is front of mind for the Government, and designing a support package alongside business will be a major part of this engagement in 2022.

“We are making a commitment to businesses in the area that significant disruption will be addressed through a comprehensive package, including direct financial support.”

Consultation on options for the second Waitematā Harbour crossing will begin this year, with a preferred option selected in 2023.