New Zealand Transport Authority spokeswoman Frances Adank said the highway was being resurfaced at the site.
About 5.30pm, the traffic jam was about 3km long.
"Loops in the road surface which detect traffic volumes and automatically adjust the traffic signals have been affected by the milling/resurfacing, " Ms Adank said.
"They will be replaced in a few days by the contractor."
The NZTA transport operations centre was manually running signals at peak hours, to ensure traffic got through, she said.
"The traffic signals will be less responsive in the off-peak hours so people might experience slightly longer delays than they are used to.
"We do ask people to be patient while the system is restored."
Related Stories
Comments
"The traffic signals will be less responsive in the off-peak hours so people might experience slightly longer delays than they are used to".
The lights are less responsive anyway, ie at night they don't recognize your vehicle as the only one in the intersection and go through their phasing as if there is other traffic.