The Brynderwyn Hills may be bypassed by State Highway 1, but a tunnel under the hills has been ruled out because of the cost.

Feedback is being sought on options for upgrading SH1, south of Whangarei, including bypassing the Brynderwyns and four-laning the highway to Te Hana.

The NZ Transport Agency (NZTA) wants public feedback on options for upgrading the stretch of SH1 to improve safety and journey reliability.

It's part of a series of initiatives NZTA is planning to improve the road alignment to reduce the number of deaths and serious crashes and provide more predictable journeys on the key route between Northland and Auckland.


The Brynderwyns, which have just undergone an $18 million upgrade on the northern side, has long been an issue for motorists, and NZTA has two possible bypass routes to cut out the winding route over the hill, but has ruled out a tunnel.

"Upgrading this section of highway to four lanes, creating a safer alignment and separating traffic will significantly reduce the high number of fatal and serious injury crashes in the area, many of which involve drivers crossing the centre line and colliding with oncoming traffic. It will also provide a more reliable and resilient freight connection to the port," NZTA system design manager Brett Gliddon said.

The proposed options for the wider route between Whangarei and Te Hana are predicted to save 280 deaths and serious injuries over 30 years, representing an estimated 80 per cent reduction in deaths and serious injuries from the existing route, based on current crash records.

Mr Gliddon said a tunnel under the Brynderwyns was considered as one of the long list of route options and was discounted because of the high cost of construction and ongoing operational safety and maintenance costs.

He said the recent $18m Brynderwyn upgrade was "online" (work to improve the existing highway) which has focused on improving safety on the north side of the Brynderwyn Hill. In contrast - the bypass will be "offline" (a new stretch of road in a new location), a divided dual carriageway entirely separate to the current route.

"This project [northern side of the Brynderwyn Hill] has delivered safety improvements to a section of the State Highway that had a high number of fatal and serious 'head-on', crossing the centre of the road, and 'run-off road' casualties in comparison with the national average," he said.

"The project has made this stretch of SH1 considerably safer and more reliable, by widening the existing road corridor, removing tight corners towards the top of the hill and installing a median wire rope barrier and side barriers on the northern side.

"The Brynderwyn Hills bypass is a longer term project with timing still to be determined and the existing SH1 over the hills is going to have an increasing level of local, tourist and freight traffic in that time.


"Even in the future, when the bypass is complete, the existing route over the Brynderwyn Hills will still be used. Having two routes in the future will meet the needs of freight, tourism and local road users with safer, more resilient and more reliable journeys."

Options for consultation include upgrading the existing road to a four-lane expressway, upgrading the existing highway for southbound traffic and building two new lanes to the west for northbound traffic, or building a new four-lane expressway either to the west or east of the existing highway.

Two options for a future bypass of the Brynderwyn Hills are also being looked at. A bypass of the Brynderwyn Hills will provide greater resilience, improved safety and will reduce the cost of travel, particularly for heavy vehicles using this section of SH1, NZTA says.

Bypass option A would run from the intersection of SH1/SH12 to the west of the Hills to Finlayson Brook Rd, while option B would go from Mountain Rd, north of Kaiwaka, west to Finlayson Brook Rd.

Public feedback is also being sought on options between Whangarei and Port Marsden Highway (SH15). Almost 22km of SH1 will be upgraded to four lanes between Whangarei and Port Marsden Highway (SH15) with construction planned to start in 2019.

"SH1 is a vital link between Northland and the rest of the country for freight, communities and tourism. Around two million tonnes of freight moves between Northland and Auckland each year and tourism in Northland accounts for $1 billion a year. Improving the region's freight connections will be a game changer for the wider Northland economy," Mr Gliddon said.

Three public information days will be held this month to explain the shortlisted options, answer questions and give people an opportunity to provide their thoughts on the plans: at Kaiwaka Memorial Hall, from 3pm to 7pm on August 15, Mata Hall, from 3pm to 7pm on August 17 and the i-Site at Whangarei Town Basin from 10am to 2pm on August 19.

Te Hana is where the northern Auckland motorway network will start, once the Puhoi to Wellsford Road of National Significance (RoNS) is finished in 2021 and planning is currently under way on the Warkworth to Wellsford RoNS section.