Police are considering whether to charge the driver of a truck that got stuck on a light traffic detour around the Brynderwyn Hills, causing hours of disruption.
The semi-trailer truck carrying reinforcing steel became wedged at a hairpin bend on Cove Road, near Waipū, about 11.30am on Wednesday.
The road reopened at 2.15pm, almost three hours later, after a Fulton Hogan recovery crew managed to free the truck.
Trucks with trailers are banned from the route, a key detour while a 10 kilometre section of State Highway 1 over the Brynderwyns is closed for repairs.
Police said their inquiries into the incident were ongoing, which included determining whether charges would be laid.
An NZTA spokeswoman said the agency, together with partner organisations such as the Whangārei District Council, was also investigating what had happened - and what needed to be done to ensure there was no repeat.
NZTA was continuing to engage with the freight industry via the Northland Inc steering group.
"As part of this ongoing engagement, we share key messaging and requirements with the industry, who in turn share this with their members. We will continue to do this during the remainder of the closure," she said.
When State Highway 1 over the Brynderwyns closed at short notice in February 2023, large trucks repeatedly got stuck at the same bend, adding to already severe traffic delays.
That prompted the council to pass a bylaw ahead of the current closure prohibiting trucks with trailers, including semi-trailers, from a critical section of Cove Road.
Wednesday's incident was referred to at the time as a crash, but no collision was involved.
A Whangārei District Council spokesperson said the organisation was waiting to see the draft investigation report before commenting.
Road crews run checkpoints at either end of the bylaw area, as well as manned traffic lights at one-way bridges along the detour.
It was not clear how the truck was able to pass through one of the checkpoints before getting stuck, or how the driver was apparently unaware of highly publicised detour rules.
Trucks with trailers of up to 50 tonnes were permitted on the other key detour route, Paparoa-Oakleigh Rd, but the heaviest trucks were required to use SH12 and SH14 around the west coast.