A major slip at the largest fill site of North Auckland’s Penlink project has forced the NZ Transport Agency to delay early opening plans for parts of the new corridor, which had been set to provide earlier access to State Highway 1 from Stillwater and Ara Wēiti.
While the $830 million project remains on track for full completion in 2028, NZTA has confirmed that it will now open as a single completed corridor rather than in staged sections.
Cracking in the ground was first identified in December last year, prompting a halt to activity while geotechnical assessments were carried out. Subsequent testing revealed a deep shear plane layer significantly weaker than expected, making it unsuitable for continued earthworks.
Due to ongoing movement at the slip site, emergency works were declared in March to fast-track remediation and protect surrounding infrastructure and private property.
Transport services regional manager Stephen Collett acknowledged the impact of the delay.
He says the delay will be frustrating to residents and road users that wanted to use the road to access State Highway 1 earlier.
“As the project uses a cut fill balance approach for earthworks, the material at this location is unable to be stored elsewhere until we can implement a solution. Until the solution can be implemented, earthworks are unable to continue at the previous pace along the alignment.”
Despite the setback, Collett says the project is still expected to open in tandem with the Wēiti River bridge.
“Despite the delay, O Mahurangi remains on track to open in line with the Wēiti River bridge, giving people the complete benefit of the project from day one. This will ensure a seamless and more connected journey to and from State Highway 1,” he says.
Meanwhile, construction continues in other sections of the site. Key progress includes:
- Beams and decking placed for the future overbridge at State Highway 1.
- Formation of ramps from State Highway 1 now underway.
- Decks poured and barriers installed along the Duck Creek Road alignment.
- Completion of the western abutment of the Wēiti River bridge and progress on both land-based and in-river piers.
- Landscaping initiated along the corridor.
- More than 600,000 cubic metres of earth—equivalent to 250 Olympic swimming pools—has been moved.
Once completed, the Penlink corridor is expected to enhance regional resilience, support growth, and improve travel times across the Auckland region.
