A re-elected National government would spend $1.75 billion to start building the first stage of South Auckland's Mill Road corridor in late 2028, the party has announced.
The money would be set aside in Budget 2028 for the first stage of the project, which runs between Manukau and Alfriston.
A further $100 million would go to NZTA in 2027/28 to protect the route for stages two and three, from Alfriston to Drury.
National's transport spokesperson Chris Bishop said the south's roading network hadn't kept pace with its growth.
"People travelling between Drury, Papakura and Manukau are funnelled onto an already congested Southern Motorway, while roads like Redoubt Road and the existing Mill Road were built for a semi-rural community, not tens of thousands of new households."
Once finished, the corridor would be a four-lane, 21.5km road running alongside State Highway 1 from Manukau to Drury.
Stage one would include a westbound bus lane at the northern end. It would also add two new and six upgraded intersections between the SH1 interchange and Murphys Rd, three new roundabouts, and new bridges over Puhinui Creek and Cheesman's Bush.
The project returns $3.10 in benefits for every dollar spent if it isn't tolled, or $2.20 if it is, according to NZTA cost-benefit estimates.
National's policy document did not say whether the road would be tolled.
"We've made strong progress on Mill Road stage one over the last three years," Bishop said.
"The NZTA Board has endorsed the investment case, and NZTA is completing the design work and taking the project through the fast-track process to secure the consents it needs."
Scathing assessment of the Government's Roads of National Significance programme (Source: 1News)
The $1.75b cost estimate figure comes from NZTA's 2025 investment case.
National has not set a construction date for the second or third stages.
The party said it would work with Auckland Council, through the new Auckland Regional Transport Committee, to settle their timing in Auckland's 30-year transport plan.
"Landowners, Auckland Council, businesses and communities need certainty about where the future corridor will go, so they can plan and make investment decisions with confidence," Bishop said in a media release today.
The Mill Road project itself has changed shape several times over the past decade.
In 2020 it was one of the largest items in the Labour-led government's NZ Upgrade Programme, at about $1.35b for the full corridor.
Funding options range from fuel tax hikes to borrowing as election-year scrutiny hits transport priorities. This story was originally broadcast in February 2026. (Source: 1News)
Costs rose to over $3 billion, and in 2021 Labour cut the project back to a smaller safety package. The current National-led government campaigned on it at the last election and revived it as a Road of National Significance three years ago.
Amid rising cost estimates, transport officials have struggled to make headway in progressing all of the motorway projects National pledged at the last election. Bishop himself conceded the projects committed to in 2023 were "long-term" commitments.
Labour has questioned how the Government would pay for its roading programme.
SHARE ME