A motorist has captured the moment a delivery truck careened over the centre line, smashing into the side of a truck, causing it to topple and block SH1 north of Auckland. 

Motorists were forced to detour for 33km after the crash at Topunui, with one driver describing it as “chaos”. 

The main road north was closed for nine hours with some drivers forced on to an unsealed, narrow road. 

The footage shows an NZPost truck travelling southbound towards Auckland from Whangārei yesterday. 

Recorded on the car following behind’s dashcam, the video follows the truck as it drives down a hill, getting dangerously close to the centre line as a truck approaches, narrowly missing it. 

When another truck, a tanker, comes through, the truck moves into the path of the oncoming truck. 

The tanker is shown taking evasive action to try to avoid the truck, causing it to tip on its side across the busy road. 

Photos of the aftermath showed the tanker on its side across the road with milk spilling out from its top. 

NZPost has been approached for comment. 

The milk tanker truck overturned on State Highway 1 between Kaiwaka and Te Hana. 

A police spokesperson said there weren’t any reports of injuries from the scene. 

The truck rolled at Topuni around 10.15am, blocking lanes in both directions near the intersections with Schiska and Otioro roads. 

A detour, which NZTA said was for light vehicles only, required both northbound and southbound commuters to travel through Mangawhai, adding an extra 33km to their journeys. 

One motorist travelling north who encountered the detour said it was “f***ing chaos” on the narrow, unsealed road. 

”The road is one car wide,” they said. 

“There’s hundreds of people trying to traverse Northland’s new state highway. 

”I’d advise anyone coming through not to use it if at all possible.”