Transport leader says 10-week SH1 Brynderwyns closure not justifiable

7:27 pm on 5 April 2024
The southern end of the Brynderwyn Hills road construction project, 2024.

Huge changes to SH1 over the Brynderwyns mean environmental impacts for surrounding native bush and native creatures such as rare Hochstetter frogs. Photo: Supplied/ NZTA

A Northland regional transport leader has slammed NZTA Waka Kotahi's 10-week closure of State Highway 1 over the beleaguered Brynderwyn Range road, north of Wellsford, saying it is a fiasco and not justifiable.

Regional Transport Committee chair Joe Carr said the scale of the resilience work over the Brynderwyns being carried out by the Crown entity was way bigger than needed.

He said the Regional Transport Committee (RTC) supported a lower-key option revealed among 530 pages of information released by the Crown entity under the Official Information Act.

This May 2023 option outlined smaller scale Brynderwyns repairs, proportionate to the risk situation and pending future final SH1 four-laning over the hills from Warkworth to Whangārei, Carr said.

He said the $25 million option would have cost less and closed SH1 over the Brynderwyns for 22 days, rather the planned 70 days. It was also proposed for June, which meant less traffic, tourism and economic disruption.

Regional Transport Committee chair Joe Carr.

Northland's RTC chair Joe Carr from Ōkaihau Photo: Northern Advocate / Michael Cunningham

Carr said the more modest choice had not been available to the RTC before his January Official Information Act request.

NZTA director for Northland/Auckland regional relationships Steve Mutton said its Brynderwyns repair work was being done to the standard to ensure it did not become another Mangamukas in the Far North, where SH1 has been out for months.

He said the smaller-scale option report was not an NZTA document, nor created at its request. It had been created independently by consulting company WSP and Fulton Hogan. NZTA's board had not considered this option, so it had not been supplied to the RTC.

"The NZTA board decided the current Brynderwyn Hills recovery and enabling works plan was necessary to decrease the risk of lengthy unpredictable closures," Mutton said.

Route reliability was among key reasons for this.

NZTA Northland/Auckland regional relationships manager Steve Mutton

NZTA Northland/Auckland regional relationships manager Steve Mutton Photo: NZME/ via LDR

However, Carr said the RTC had asked for the Brynderwyns fix project to be peer reviewed before it went ahead. That had not happened.

He said the scale of the current work threatened the likelihood of getting a better SH1 route alternative as part of future Warkworth to Whangārei four-laning.

Huge quantities of earth are being moved in the road works during the latest Brynderwyns SH1 closure that started on 26 February, 2024.

Huge quantities of earth are being moved in the road works during the latest Brynderwyns SH1 closure that started on 26 February, 2024. Photo: LDR/ Northern Advocate - Michael Cunningham

Carr said there was inadequate geotechnical justification for the claim the Brynderwyns road was at risk of catastrophic failure and therefore needed urgent work, which meant a lengthy closure.

Earlier this year, he sought supporting information for the current works via an Official Information Act (OIA) request.

"The RTC has been running on an information deficit from NZTA around the Brynderwyns project," Carr said.

He sought the full geotechnical report NZTA Waka Kotahi's board had used to justify the work that was currently being undertaken.

In a letter with Carr's OIA response, NZTA chief executive Nicole Rosie said a full geotechnical report had not been done to underpin the Brynderwyns work.

"In making the decision for the short to medium-term solution, a full geotechnical report was not completed," Rosie said.

The cost of the Brynderwyns SH1 project resilience work has climbed to $75m, up 23 percent on its previous $64m bill.

NZTA's Mutton told the RTC meeting in Whangārei on Tuesday that a further $15m had been added to the $64m project.

That $64m figure is up on what the Crown entity's website in February described as a $61m project.

The Waipū to Mangawhai route will bypass the SH1 Brynderwyns road as the roadworks are carried out.

The Waipū to Mangawhai route is one of two where $140 million of upgrades have been necessary because of the state highway closure. Photo: Local Democracy Reporting

Mutton said the cost increases were driven by consent conditions as well as meeting environmental requirements - New Zealand's rare native Hochstetter's frogs needed to be moved as some of their habitat would be destroyed along the road works corridor - and also shifting more dirt than originally planned.

Carr said the huge economic hit Northland was facing on top of construction costs meant the region was losing at least $2m a day, which amounted to $140m over the 10-week closure.

He cited one trucking company operator running 17 trucks who had gone under as a result.

Mutton said NZTA had a duty to ensure a high level of service on the state highway network and to manage the risk of any expected issues.

Excavators at work near Waterfall Corner as part of a major roading project on the SH1 Brynderwyn Hills road.

Excavators at work near Waterfall Corner on the SH1 Brynderwyn Hills road. Major earthworks are a feature of the multi-million dollar resilience work being carried out. Photo: Supplied/ NZTA

SH1 over the Brynderwyns had unique challenges due to its geology and varying terrain.

"The probability of the road closing in any given year due to an extreme weather event has been calculated at 100 percent," Mutton said.

"Without the current recovery and enabling works, we would anticipate six to eight short duration closures (lasting days) and one long duration closure (lasting weeks or months) over the next year."

Carrying out the work would significantly enhance the road's level of service and prevent long duration closures, he said.

"This ensures the key corridor remains reliable, safe and efficient for Northland communities, industries and visitors to the Northland region."

He said the current resilience work did not preclude a longer-term solution for the area, which NZTA was investigating.

Mutton said it was not common for NZTA's board to directly request geotechnical reports.

He said NZTA presented to the RTC about the Brynderwyns in December and continued to regularly meet the committee to provide updates. Its weekly updates were also shared with the RTC.

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

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