The first vehicles should start going over a repaired State Highway One at Pukenui by noon on Thursday, with the stricken road fully opened by late that evening.
State Highway 1 south of Pukenui was closed after a washout between Whalers and Lamb Rds, last Friday, leaving no other appropriate routes between Kaitaia and Cape Reinga.
Locals and visitors have been escorted through forestry roads in convoys over the past two days, and New Zealand Transport Agency had hoped to have the road reopened by tomorrow.
However, an NZTA spokesperson said one lane of the road would open around noon on Thursday with two lanes opened by Thursday evening. While the aim had initially been to have all or part of the road ready by tomorrow, that had not been possible due to the nature of the work.
The route across the washout area will be gravel, not a sealed road and some delays are likely. Convoys through the forest for essential travel only will continue until the road opens on Thursday.
It has been a big job to do, with contractors working 5 metres below the road level on a sandy base, which has made the work tricky and has had safety challenges.
Altogether 11 pipes which are 2.1 in diameter have been laid to form a new culvert under the road and the stream has been diverted to run through the pipe,NZTA's Northland System Manager, Jacqui Hori-Hoult, said.
Backfilling is now well under way to cover the pipes up to road level. About 5,000 cubic metres of material is needed to fill the gap left after the washout created a hole about 20 metres long and 4-5 metres deep.
"The conditions on site and difficult access have meant progress has been slower than anticipated. There is no overnight work for safety reasons, but work will resume at first light tomorrow," Ms Hori-Hoult said,
"The Transport Agency understands the closure is frustrating and we thank people for their continued patience and understanding, especially towards our road crews on site as they work to reopen the road.''