A surge of container-laden trucks on State Highway 1 between Auckland and Whangārei is expected over the coming days.
From tomorrow, 800 trucks will carry nearly 1200 containers of Christmas cargo south from Northport.
They are from the ship Constantinos P, which was diverted to Northport because of delays in unloading in Auckland.
The Transport Agency says up to a dozen trucks will leave Northport hourly, from 6am to midnight for about seven days.
Empty trucks will then make the return journey for another load.
Road Safety Forum chief executive Nick Leggett told Morning Report the road was not up to a standard that it could take that number of trucks on a regular basis, but this was a special case.
"What we're seeing is these people who usually move in and around Auckland every day - they might go to Auckland port four or five times a day to drop containers - are now being turned into long-haul drivers.
"They'll be going to Whangārei which is a round trip of about 300km. There are different pressures and it's moving into peak season. There's pressure in terms of the freight that's coming off the ship and getting it to where it needs to go as quickly as possible."
Leggett said it was good hear officials say they would keep an eye out on the route.
"I think the drivers will be really aware that they've got to monitor their fatigue and look out for other road users and so will their employers."
The advice for other motorists remained the same as usual - keep to the speed limit, be cautious, and don't drive under the influence or while fatigued.
Leggett urged those receiving the freight and road users to be patient as the supply chain around the world had been challenged by the pandemic.
"As I say it's a special case, these containers have to be moved ... the silly season always causes silly behaviour around about Christmas and I think we've just got to be watching out."
Freight owners will also have to face up to added costs as the extra kilometres of driving are counted up.
Leggett said the extra costs of taking freight from Northport to Auckland showed why Northport was not a viable option to move freight operations to, as had been recommended last year in a working group report to the government.
"Our position has always been that we didn't support the move to Northport. You might say this is an audition for Northport but equally it could be the nail in the coffin in the sense it is very distant from the Auckland destination of most freight."
Although 50 to 60 containers could be put on rail, he said, the infrastructure to carry out the transport wasn't there.
"The railway line between Whangārei and Auckland is currently closed until mid-January so the infrastructure, both road and rail, is not up to scratch."
He said this would be an interesting test for Northport.
"Northport have never had a ship this size, and they don't really have the infrastructure to get these containers off. We're very supportive of this happening obviously and the trucking industry does what it always does - which is stand up and move the freight."