The massive slip at Lemons Hill between Kawakawa and Paihia could need a bigger clean-up job than first thought.
Engineers are still assessing the slip that closed State Highway 11, with a question mark now over the initial estimated two weeks before the hillside could be made safe.
The New Zealand Transport Agency's system manager Steve Mutton said the slip appears to be bigger than first thought.
Clearing of vegetation and site preparation work is underway but heavy rainfall expected next week when ex-Tropical Cyclone Gita hits the country could delay the start of larger earthworks.
Traffic between Opua and Kawakawa will continue to detour via SH1, SH10 and SH11 until the Lemons Hill road is opened.