Concerns have been raised over the safety of the The Ara Tūhono - Pūhoi to Warkworth motorway project after risk registers were released to Radio New Zealand under the Official Information Act (OIA).

The August and September risk registers revealed that the project had a "high" to "extreme threat" of landslides due to earthworks being exposed to wet winter weather for longer than expected, thanks to a construction hiatus forced by Covid-19.

"Measures put in place to mitigate the risk of a landslip delaying construction include reviewing the design as more detailed geotechnical data becomes available, especially in high-risk areas," Waka Kotahi told RNZ.

The land on which the motorway is being built is known to have soils that can be difficult to work on, a problem amplified by the delays in earthworks. 

Waka Kotahi are confident the build is of "a high standard, with robust quality controls, which will ensure that the motorway and all of its structures are durable, safe and fit for purpose".

The designs are being reviewed, as are the project's insurance and legal protections, and potential landslide threats.