Contractors have continued their work overnight on a 100 metre-long detour to bypass the SH1 slip at Maromaku.
The NZ Transport Agency said damage from the recent storm is so extensive it may take some time to fully restore the region's roading network.
Work on SH1 has seen vegetation cleared near the site and work has started on the construction of the diversion. Officials hope if the weather remains favourable the bypass could be opened by the end of the week.
Transport Agency's Regional Journey Manager Jacqui Hori-Hoult said they had to be absolutely sure the ground was stable enough to safely open the by-pass around the washout.
The main alternative route for all vehicles between the Far North and destinations further south remains SH12 through Dargaville and Kaikohe.
The detour can be accessed from the SH1/SH12 intersection at the Brynderwyn Hills, or from SH14 between Whangarei and Dargaville.
It may add up to 2 hours to journey times.
Ms Hori-Hoult said work to widen SH12 at Kaihu, 30 kilometres north of Dargaville, will be completed today.
A 70 metre-long section of the highway was washed away by flood waters.
People using Ruapekapeka Road as a detour are reminded it is unsealed and winding, and extreme care is needed.
It is open only to light vehicles, and there is no access for heavy vehicles.
Mangakahia Road remains closed to heavy vehicles north of Twin Bridges.
South of Whangarei, crews are busy repairing potholes and clearing slips and drains.