Politicians and bureaucrats are gearing up to find a permanent solution to State Highway 1 over the Brynderwyns, which was closed to traffic after this summer’s storm events.

Two bypass routes to the west of the Brynderwyns are part of a business case for SH1 between Port Marsden and Te Hana, being undertaken by Waka Kotahi NZ Transport Agency.

This comes as the National Party is promising to invest in roads damaged by Cyclone Gabrielle and the Auckland Anniversary floods, including the Brynderwyns, SH1 at Dome Valley north of Warkworth, and SH25 in the Coromandel.

National transport spokesman Simeon Brown said the party would not announce its transport policy until after this month’s Budget, but said it would include improved roading resilience in the regions.

He would not say if National would stick with its 2020 election policy to build a four-lane highway from Whangārei to Auckland, including a tolled tunnel under the Brynderwyns in the following decade.

Meanwhile, Waka Kotahi said the recent storms and impacts on the Brynderwyns will be fed into a review of the two possible bypass routes identified in a programme business case for the Whangārei to Auckland corridor in 2018.

The next step for the crucial connection to and from Northland for people and freight is a business case to assess the options and timing of investment, “including the resilient long-term solution for the Brynderwyn Hills”, a Waka Kotahi spokeswoman said.

The business case will be considered for inclusion in the new 2024-2027 National Land Transport Programme that sets out Waka Kotahi’s funding plans over the next three years.

Since the summer events, the Brynderwyns, about 45km south of Whangārei, have been fully or partially closed to repair numerous slips. It reopened in both directions today.

Waka Kotahi regional maintenance and operations manager Jacqui Hori-Hoult said workers will still be on site removing material from the southern slip sites, with traffic management and a temporary speed limit remaining in place.

Joe Carr, chairman of the Northland regional transport committee, said the Brynderwyns are of huge importance, carrying huge volumes of freight and 790,000 tourists a year to the region.

“When that route is disrupted, it has a huge cost to Northland,” he said.

Carr said the committee would like to see a desktop study into a possible alternative route from the summit of the Brynderwyns heading south to take advantage of the $25m invested in improvements to the northern side.

“It may end up in the rubbish bin, but boy-oh-boy it we could get something like that to go ahead that would be great,” he said.

The committee would also like to see a three-lane highway from Te Hana to the Brynderwyns turnoff and any improvements on the northern side to be four lanes.

Meanwhile, Waka Kotahi is still anticipating the new $880-million Pūhoi to Warkworth motorway will be open before the end of June.

The timing of the road opening will be decided once NX2 – a joint venture between Fletcher and Spanish construction firm Acciona – and an independent reviewer are satisfied all the safety and quality assurances have been met.

The 18.5km route will chop 11 minutes off the current route, be a much safer and more reliable drive for the 24,000 vehicles who use the road every day, and connect to Auckland Transport’s $62m Matakana link road that avoids Warkworth’s infamous Hill St intersection.

In another transport development north of Auckland, Transport Minister Michael Wood has announced the O Mahurangi Penlink project, the $830m road connecting the Whangaparāoa Peninsula with SH1 in Auckland, will be tolled.

There will be a $3 charge during peak hours and a $2 charge at other times. Heavy vehicles will pay double these rates.

“By using a tolling model the community can be assured the road will be maintained to a high level as there will be guaranteed income that will only be used to maintain this road,” said Wood, saying the new road will cost $3m a year to maintain.

The long-awaited link road is due to open in late 2026.