Northland: SH1 Brynderwyns viaduct proposed by transport leaders

9:43 am on 11 September 2023
Works on the Brynderwyns section of SH1, a month after Cyclone Gabrielle. Huge efforts by hundreds of kaimahi (workers) was needed to repair the road.

Works on the Brynderwyns section of SH1, a month after Cyclone Gabrielle. Huge efforts by hundreds of kaimahi (workers) was needed to repair the road. Photo: Supplied/ Waka Kotahi NZTA

A kilometre-long Brynderwyns viaduct is the best fix to solve "unacceptable" State Highway 1 closure issues, Two Northland transport leaders say.

Northland Regional Transport Committee (RTC) member Simon Reid said a Waka Kotahi NZTA-funded viaduct up the hills' southern flanks would bring a cheaper and easier solution to repeated closures.

Reid, who is also Whangārei District Council (WDC) infrastructure committee chair, said there had been too much talk and not enough action to find a solution.

He is proposing the viaduct, along with fellow RTC member and Whangārei Deputy Mayor Phil Halse, and said the option would see the viaduct built on the Brynderwyns' southern flank, replacing SH1's existing winding corners, and located to the east of the current route.

Northbound vehicles would head off SH1 at the foot of the Brynderwyns' southern side. The start of this viaduct route would go over part of Atlas Quarries' property.

On the Brynderwyns' south side, the new viaduct idea would direct traffic north over a quarry (to the right and back of this photo), instead of the existing SH1 route (left).

On the Brynderwyns' south side, the new viaduct idea would direct traffic north over a quarry (to the right and back of this photo), instead of the existing SH1 route (left). Photo: Local Democracy Reporting/ Northern Advocate - Tania Whyte

Vehicles would head up the viaduct that transitioned into roading then crested the Brynderwyns. They would then rejoin the existing SH1 at its summit, via Artillery Road's current track on the Brynderwyns' northern side.

The same would happen in reverse for southbound vehicles.

Northland transport leaders Simon Reid (left) and Whangārei Deputy Mayor Phil Halse at the Brynderwyns SH1 summit where their proposed viaduct would run.

Northland transport leaders Simon Reid (left) and Whangārei Deputy Mayor Phil Halse at the Brynderwyns SH1 summit where their proposed viaduct would run. Photo: Local Democracy Reporting/ Northern Advocate - Tania Whyte

Reid said it was unfortunate the government had failed to add the viaduct to the two western SH1 Brynderwyns route alternatives in recent national priority roading announcements.

"This announcement included two western bypass options, produced years ago, but failed to mention the third viaduct option, presented to Waka Kotahi NZTA at a recent RTC meeting."

In 2017, Waka Kotahi NZTA sought public feedback on two alternate indicative route options to the west of SH1 over the Brynderwyns. This project was placed on hold in 2018.

Reid said the viaduct was a local solution to an issue that needed fixing.

"This simple, practical solution involves a new road alignment on the south side of the Brynderwyns, connecting to a viaduct and a new road to the summit," Reid said.

It could be built in two years, less than a quarter of the time of the other alternate route options recently put forward by Waka Kotahi NZTA.

The two years compared with the projected 10 to 15 years for the other options, Reid said.

He said the Waka Kotahi NZTA-funded SH1 viaduct project could be Northland made.

"It could be completed solely as a Northland regional project, with all work done by Northland-based companies who are capable and keen.

"With the support of Waka Kotahi NZTA this viaduct option would save millions of dollars, bypass consultants and offer a high-quality solution that overcomes the Brynderwyns' constant SH1 closures."

A sign at the Brynderwyns in March this year, a month after Cyclone Gabrielle hit.

A sign at the Brynderwyns in March this year, a month after Cyclone Gabrielle hit. Photo: Local Democracy Reporting/ Northern Advocate - Michael Cunningham

Constant closures were unacceptable. A solution was needed more quickly than appeared to be happening, he said.

"Northland needs a guarantee the Brynderwyns fix will be completed ASAP.

"We need immediate forward action on the Brynderwyn problem," Reid said.

The viaduct was a well-supported and thought out locally, offering the best solution.

In response to the new viaduct call, Waka Kotahi NZTA regional manager system design Randhir Karma said all alternate SH1 Brynderwyns options would be reassessed, against government investment objectives at the time, should that development work recommence.

But he warned Brynderwyns options were not currently on the table.

"We understand how important it is to the community to get certainty around when this project may be built.

"However we do not currently have funding to progress this work further. When funding does become available this project will be prioritised against other projects and programmes across the country," Karma said.

In 2017 Waka Kotahi NZTA sought public feedback on two shortlisted indicative route options to the west of SH1. This mahi was placed on hold in 2018. There has been no further work on the mahi's Whangārei to Te Hana business case since.

"Prior to public consultation on two shortlisted options in 2017, Waka Kotahi assessed a number of options against the investment objectives of the time. These options were published on Waka Kotahi NZTA's website," Karma said.

He said Northland's RTC proposal was one of two received by his organisation since 2017.

Local Democracy Reporting is Public Interest Journalism funded through NZ On Air