Slip 9 on the northern end of the gorge. This slip requires the most complex engineering solution and will take approximately 8 months to fix.

SH1 Mangamuka Gorge April progress update

Kia ora koutou,

Work in the Mangamuka Gorge is tracking well and the team has begun installing piles at five out of the 15 slip sites to strengthen the road so it’s stable enough to accommodate the large machinery needed to carry out slip repairs.

Additionally, drainage work has been completed at seven of the most critical slips which will prevent any further movement, capture, and divert rainfall efficiently and help to protect the environment we’re working in.

There are almost 90 crew members working on site at any given time across several worksites operating in parallel. As you can imagine, the gorge is buzzing with activity!

As we’re working in a constrained environment with large machinery, multiple worksites, and lots of people, we’re doing everything we can to ensure the safety of the crew and the integrity of road. This means movement of materials around site needs to be carefully planned.

Most crew members live locally and are working hard to get the gorge reopened for their friends and whānau who rely heavily on this part of the state highway for work, recreation and to stay connected to their communities.

We’re incredibly grateful for their hard mahi and the positive culture they’ve created on site.

SH1 Mangamuka Gorge is planned to reopen and be fully operational by May 2024. We are actively investigating options for restricted light vehicle access over the summer holiday period and will provide more information on what’s possible closer to the time.

What's coming up?

Our crews are continuing to install piles across seven of the slip sites and will also complete the capping beam (which ties all the piles together) on the northernmost slip.
There are approximately 700 piles to install across all sites so it will take some time, as some of the piles are drilled as far as 20m deep into the ground.

Click the image above to listen to the Te Hiku Radio interview

Project Director Norm Collier has a kōrero with Te Hiku Radio

Recently, our Project Director Norm Collier sat down for a chat with Te Hiku Radio to give a progress update on the slip repairs.

During this interview, Norm covers off how we’re fixing the slips, working with hapū, the excellent team culture created by locals working on the project and more.

Click here to listen to the interview.

Need more information for your local community group?

Our latest flyer ensures you and your community are kept up to date.

If you would like some printed copies to hand out to your whānau or community group, send us an email at northlandproject@nzta.govt.nz with your name, mailing address and the number of copies you need. We’ll then pop them in the post directly to you.

To view the electronic version of the flyer, click here.

One of the pupurangi (Kauri Snail) found during a biodiversity walkover

Caring for the environment

Protecting and enhancing the environment we’re working in is critical to us and our partners as the Maungataniwha Ranges are home to a diverse range of native and endangered flora and fauna. Just a few of the ways we’re minimising our environmental impact on the gorge includes:

Preventing Kauri Dieback
Kauri trees need to be protected from Kauri dieback disease – a fungus which damages the tree’s root system and can kill it.

We have multiple cleaning stations within the gorge and our people are required to clean any footwear and equipment that may touch the ground before and after being on site. We’ve also got a plan for how we manage the safe movement of soil and vegetation into and out of our work sites.

Protecting native species
We work closely with New Zealand Environmental Management and hapū to regularly survey any native or endangered species which may be at risk of impact by our work and relocate them away from our construction sites. Recently, we found several pupurangi (Kauri Snails), hura (New Zealand giant centipede), copper skinks, multiple wētā species and North Auckland worm. These species were all safely moved them deeper into the forest.

Stormwater and sediment management
Effective stormwater and sediment management plays a major role in protecting the environment through construction. We’re installing silt fencing, rainwater capture drains and sediment tanks to ensure any stormwater runoff is collected, diverted, and treated before it reaches the local waterways.

More information

For more information on the SH1 Mangamuka Gorge slip repairs, contact us at northlandproject@nzta.govt.nz

Visit our website www.nzta.govt.nz/mangamuka