Brynderwyn Hills recovery and enabling works

12 March 2024

Core sampling machine working at night

What's been happening this week

It seems remarkable that we are in the third week of the closure now and heading quickly towards Easter when we will reopen the road for six days from March 28 (12:01 am) to 2 April (11:59pm). 

Despite the weather our recovery operations have continued and are on track at the various work sites. We are making good progress, and the real advantage of the closure is the ability to work both day and night. As you can see in the image above, crews are busy while most of us are sleeping. 

In this image, the crews are drilling down to check the strength of the pavement layers, using a core sampling machine. After drilling to a depth of five metres, the core sample is taken out and examined by an engineer to determine important information about the characteristics and what the ground is made of such as:

• where there may be faults at specific depths
• the depth of the underlying rock along with its strength
• the ability to hold to the planned horizontal nails used to support the wall or road.

We have now inducted over 520 staff to the project and continue to make great headway, having now cut approximately 66,500 m³ of soil! 

Progress in pictures

The photos below show one of the southern sites contributing towards the total 66,500 m³ of soil excavated so far. You can also see this as timelapse footage on our NZTA Northland Facebook page. 

Follow the NZTA Northland page to stay up to date with weekly progress photos and footage. 

Photos of the southern side of the Brynderwyn Hills taken 27 February (top image) and 11 March (bottom image)

Temporary traffic lights on Cove Road detour

We have been asked by some members of the community about the signage and traffic lights set up at checkpoints and one lane bridges along the Cove Road detour. 

The Cove Road route signage turns people off at the Kaiwaka Mangawahi Road intersection and takes them through Garbolino Road, Tara Road, Cove Road, Nova Scotia Drive and back to SH1. The southbound trip is the same in reverse order.

Traffic lights at some bridges on this route temporarily replace the current one-way system, helping to avoid lengthy queues on the give way approach to the one lane bridges. 

At the two checkpoints, traffic lights are used so that staff can ensure truck and trailer units are unable to use Cove Road (Mangawhai Heads to McLean Road section) as directed under the Whangarei District Council and Kaipara District Council by-law. You may have seen one of the checkpoints at the intersection of Cove Road and Mangawhai Heads Road which is also close to a single lane bridge.  

We understand it can be frustrating to wait in a queue but please bear with us while these controls are in place and appreciate our traffic controllers have an important job to do.

Soil nails being installed at another Brynderwyn Hills site in 2023

Stabilising the slopes

One of the key recovery tasks we are undertaking is to stabilise the slopes and build retaining walls to prevent future slips.  One method we are using is known as soil nailing. 

What is the purpose of soil nails? Soil nails are used as a method of stabilising slopes and retaining walls all over the world. They work by drilling multiple anchor rods through unstable shallow ground or retaining wall and anchoring them into the deeper hard rock below. The deep ends of the rods are grouted to lock them into the hard rock while the open ends are capped and often connected with concrete or mesh to help secure the top layer of soil.

How long are they? Soil nails can vary in length depending on how deep the rock is at different locations. Soil nails used on this project will be approximately 15m long. Soil nails are drilled by a specialist excavator attachment.

How do you install them? Soil nails are installed by drilling each hole to the required depth. The holes are flushed during this process to ensure all laitance (weak, fine materials) is removed from the hole and a strong bond can be achieved. Soil nails are then installed and grouted to lock them into the hard rock. The open ends are then capped and often mesh or/and concrete used to cover the unstable face and secure the top layer.

Racing snail in action at the Brynderwyn Hills site

Site housekeeping

A safe site is a clean site. This skid steer with broom (pictured above) sweeps the road 12 hours a day, keeping unwanted material off the road and stopping it from being spread further by work vehicles and preventing the road from becoming slippery in rain. Nicknamed ‘Racing Snail’, it weighs in at 5 tonnes and has a maximum speed of 20km/h.

Meet the team- Shaun Grieve

What is your role? I'm a Principal Geotechnical Engineer taking charge at the Brynderwyns site as the geotechnical lead.

What is your connection to the area? I'm as Northland as it gets – born and raised! Now, I've set up camp in Ruakaka with my family. I wear quite a few hats around here: chairperson at Ruakaka Kura, leader with the Bream Bay Scouts, and an active member of the Ruakaka Residents and Ratepayers Association. Having worked on the Northland State Highway network for the past nine years, my connection to the land here runs deep. I totally get how crucial this road is for the 200,000 folks calling Northland home. 

Why is this project special? This isn't just another road project; it's our lifeline. Northland has always been at the mercy of the weather, affecting our access to crucial services and resources. This project is about safeguarding our connection to the essentials. 

Favourite place in Northland? The northern stretch of Ruakaka Beach – it's my slice of paradise.

Tell us something about yourself Family and community are my world outside of work. Between being a proud Northlander, a family man in Ruakaka, chairing at Ruakaka Kura, leading the Bream Bay Scouts, and contributing to the Ruakaka Residents and Ratepayers Association, my plate's pretty full with things I love.

Key information at a glance

SH 1 Brynderwyn Hills closure status

Closed: 26 February (12:01 am) - 27 March (11:59pm)

Open: 28 March (12:01 am) - 2 April (11:59 am)

Closed: 3 April (12:01 am) - 12 May (11:59 pm)

Three scenic detour routes

Cove Road route: Turn off at Kaiwaka, use Kaiwaka Mangawhai Road, Garbolino Road, Tara Road, Cove Road, Nova Scotia Drive and connect back to State Highway 1. (Restrictions are in place for trucks with trailers on Cove Road between Mangawhai Heads Road and McLean Road).

Paparoa Oakleigh Road route:Trucks and trucks with trailers up to 50 tonnes can use this route.

SH12/SH14 route: HPMV (high productivity motor vehicles) must use this route.

Local routes contact: 

Whangarei District Council 0800 932 463

Kaipara District Council 0800 727 059

State Highway route contact:

NZTA 0800 444 449

More information

For more information on the SH1 Brynderwyn Hills project, contact us at northlandproject@nzta.govt.nz

Visit the project website www.nzta.govt.nz/brynderwyn-hills