Motorists say confusing road markings are confusing drivers on Auckland's Northwestern Motorway.
Some have reported swerving into other lanes or had other motorists swerve into them.
Recent roadworks have seen old lane markings covered up with black paint, but at peak times, they shine in low sun so it has become difficult to tell the difference between the old and new markings,
"When the sunlight's on that gloss finish... you can't really work out that it's a black marking," said one commuter, who preferred not to be named.
The man said he'd had a large truck veer into his lane. He'd also driven across two lanes himself, as had a car in front of him.
"I have noticed some vehicles doing the same as me where their... brain has interpreted the wrong set of lanes and they've swayed over to another lane."
The markings between the St Lukes off-ramp and the causeway seemed unsafe, he said.
He said orange paint had previously been used to distinguish the new from the old markings on the same stretch of road. It would make sense to do that again or to give the black paint a matte rather than a gloss finish.
NZ Transport Agency's Auckland highway manager Brett Gliddon said the agency had carried out several inspections to identify the areas where the shadow marking on State Highway 16 needed to be addressed.
They had been treated by water-blasting to remove the paint markings that were no longer needed.
"However this can still result in a roughened texture which can be difficult to differentiate from new markings. We will continue to monitor and carry out more remedial work.
"The best solution is to resurface the road, which will happen over the next few months."
Because of the extent of the work it would take several months to carry out. It was being done overnight to minimise the impact to traffic during the day, said Mr Gliddon.
"We understand the shadow marking can be confusing for motorists and we're working hard to improve this."
He asked that motorists to complied with the reduced speed limit of 80km/h through the area until NZTA could resurface the road.