NZTA Hawke's Bay system manager of maintenance and operations Martin Colditz said the subsidence looks to be the result of heavy and sustained rainfall and warned: "This will not be a quick-fix and people should expect the road to remain single-lane for some time."
It will need to investigate to understand the underlying cause before it is able to identify and progress design for the appropriate fix.
"Engineering resource is significantly stretched across the country at the moment due to the large number of weather and geological events," Colditz said.
"This means we don't yet have a timeframe for repair, but will keep the community informed as work on this progresses."
It's another blow for the 116km of SH2 from Napier to Wairoa, which included single-lanes and speed limits on the Esk River bridge near the SH5 intersection between Bay View and Whirinaki.
A stretch of the Hawke's Bay Expressway, from Longlands to Pakowhai Rds, was included in the caution.
A police spokeswoman said a slip on the Napier-Taupō Rd reported about 11pm Monday, brought the road down to one lane. It appeared to be fully reopened the next morning.
Pothole repairs were in full swing on a sunny Wednesday, readying for Thursday's predicted freeze.
A Hastings District Council spokesperson said 88 potholes had been reported and repaired over the past week alone.
"There have not been any particularly significant roads affected, they have been spread across the rural and urban network."
A Napier City Council spokeswoman said the council had received four reports related to potholes in the past week, and they were not necessarily rain-related.
