Difficult ground conditions for workers mean the massive washout which closed State Highway One north of Kaitaia on Friday won't be repaired for traffic to pass until tomorrow.

Traffic should be able to get through the repaired highway around noon tomorrow, when one lane would be due to reopen, with both lanes expected to be open by tomorrow evening.

NZ Transport Agency had initially hoped to have the highway repaired and reopened by today.

NZTA Northland system manager Jacqui Hori-Hoult said difficult ground conditions have slowed efforts to repair the washout.

Advertisement

Contractors have been working five metres below the road level on a sandy base, which has had safety challenges.

''The route across the washout area will be gravel, not a sealed road and some delays are likely,'' Hori-Hoult said.

Crews are working to back fill the large hole with 5000cu m of material. A larger, 2.1m diameter pipe has been laid to provide more resilience across the culvert.

She said NZTA understood the frustration the closure caused and its team on site was working as hard as they could to reopen the road and provide a permanent solution to the drainage challenges in the area.

''It's too dangerous to do any work overnight but work will resume at first light [today]," Hori-Hoult said.

Convoys through the forest - for essential travel only - would continue until the road opens.

This morning's convoy would leave at 7.30am for southbound traffic from the corner of Far North Rd and Trig Rd and at 8.15am for northbound vehicles from 113 Hukarere Rd at the end of the sealed section.