SH1 Mangamuka Gorge slip repairs

Project update

30 October 2024

A section of completed pavement repairs between Slips A9 and A26

SH1 Mangamuka Gorge slip repairs – October 2024 update

Kia ora koutou,

We are excited to announce that the road through Mangamuka Gorge will fully reopen to traffic in both directions at 12:01 AM on Friday 20 December 2024.

The team continues to work at pace, making great progress as we get closer to reopening. In the past month, we’ve ticked off some big achievements, all 1,337 piles are now complete (see below for some interesting info on the scale of piles), we’ve finished 80% of the anchors and completed repairs on 3 more critical slip sites. That takes the total completed critical slips to 9 out of 16, with the remaining 7 slip repairs in the final stages. This includes installing safety barriers, drainage systems, and rebuilding the road surface.

Thank you for your continued support!

Additional works required after the holiday break

After the holiday break, we will need to come back to do some additional work to complete the repairs. The road will stay open while we do this, but some sections will operate under reduced speed limits or stop/go controls.

We're finalising the details of the remaining work and will provide more details in next month's newsletter.

Media

Listen to the latest interview with our Project Director Mark Ware as he gives an update on the project and its progress:

Te Hiku Media: Mangamuka Gorge on Target for Reopening in Time for Christmas

Upcoming events

Join us at the Kaitāia Markets on Saturday 2 November to hear more about the progress we're making on the slip repairs on State Highway 1 through Mangamuka Gorge. 

We'll be at the markets at 11 Matthews Avenue in Kaitāia from 7am to 12:30pm – come along and ask your questions!

Keep an eye out on our social media channels for any updates:

NZ Transport Agency Waka Kotahi – Northland Facebook page

Click on the image above to hear from Kylie Harris - PR Manager, CLL Services and Solutions, as part of our worker profile series featuring a few of the team working on the project (filmed earlier this year).

Behind-the-scenes project videos

If you missed them over the last couple of months, check out our behind-the-scenes project progress videos. These updates provide a glimpse into various aspects of the project and the people involved, with more uploaded every month.

Voices of Mangamuka Gorge: Kylie Harris

Voices of Mangamuka Gorge: Pene Subritzky

Voices of Mangamuka Gorge: Brenda Reichardt

Voices of Mangamuka Gorge: Howard Mills

How local workers are shaping the future of Mangamuka Gorge

Rebuilding Mangamuka Gorge: complex engineering for extreme weather

Mangamuka Gorge nightworks

Planned Northland Summer Maintenance 2024-2025

Largest ever summer work programme across Northland

This summer, NZTA will invest in one of the largest road rebuilding programmes for state highways in Te Tai Tokerau Northland's history. In addition to regular maintenance, we'll be resurfacing and resealing many state highways across the region.

Overall, we'll be rebuilding 36.5 lane kilometres, resurfacing 16.1 lane kilometres, and resealing 157.9 lane kilometres, totalling 210.5 lane kilometres of improvements. This work will take place on state highways from Te Reinga Wairua (Cape Reinga) to State Highway 16 north of Woodhill and State Highway 1 north of the Johnstones Hill Tunnels.

These upgrades are crucial for making your travel safer and more enjoyable. We’ll do our best to minimise disruption, including working at night or during off-peak hours. To reduce congestion during the holidays, all renewal work will pause from Friday 20 December 2024, to Monday 6 January 2025.

A big thank you to the roadworkers who will be improving our roads throughout the summer! The warm temperatures and dry air will help ensure a quality finish. Please drive safely through work zones, follow all signs and instructions from roadworkers, and give them a wave to show your appreciation for their hard work.

For details on where the work will be happening, visit: Northland state highway maintenace programme.

*Lane kilometres count the number of lanes on a road, providing a more accurate picture of the work being done, including passing lanes. For example, a four-lane, 10-kilometre stretch of road has a total of 40 lane kilometres.

Slip A11 – Drainage and road surface installation under way and is now complete

Progress update

With the completion of piling on all the critical slips, the piling crews have now left the site and multiple anchor and pavement teams are making great progress throughout the gorge.

In addition to reinstating the road around the slip sites, the pavement teams are also repairing areas where we have installed new culverts.

Slip A47

Rehabilitation works: 31/31 permanent piles complete.

Lagging is now underway. The pavement teams are also now onsite to reinstate the road surface around the slip site.

Pouring the last piles.

Slips A1 and A2

Rehabilitation works: 40/40 permanent piles complete. 13/40 anchors complete

Two anchor crews are on site and are making impressive progress with the drilling and installation of casings, anchors and testing the anchors.

Anchors being installed and tested.

Slip A3

Rehabilitation works: 40/40 permanent piles complete. 42/42 anchors complete.

The guardrails have been installed. Reinstatement of the road will complete all works on this slip.

The guardrails have been installed.

Slip A4

Rehabilitation works: 36/36 permanent piles complete. 36/36 anchors complete.

Slip repair is complete, with just the reinstatement of the road left to do.

Ready for the road resurface to be reinstated.

Slip A5

Rehabilitation works: 25/25 permanent piles complete. 25/25 anchors complete.

The guardrails have been installed. The site has been milled and ready for the reinstatement of the road surface.

Slip A6

Rehabilitation works: 54/54 permanent piles complete. 44/44 anchors complete. 

Slip repair is complete. Reinstatement of the road is underway with the installation of the subbases and subsoil drains.

Road surface installation. Subsoil drains are being installed to improve drainage under the subbase.

Slip A7

Rehabilitation works: 54/54 UC (Universal Column) piles complete.

Lagging and backfilling is complete and awaiting anchors. This will be part of the work completed in the new year, under temporary traffic management. The anchoring system required for this slip is much smaller and shorter than the larger piled walls.

Piling, lagging and back filling is complete and ready for road reinstatement.

Slip A8

Rehabilitation works: 68/68 permanent piles complete.

This slip repair is now complete. Bore drainage has now been drilled under the road to complete this slip repair, and the team are now tidying up the work site below the road. The milling machine has milled the top surface off the road and the wearing course membrane has been laid ready for the asphalt reinstatement.

The road has been milled and the bitumen membrane has been laid ready for asphalt.

Slip A9

Rehabilitation works: 53/53 permanent piles complete. 42/52 anchors complete.

Roading repairs are underway with the reinstatement of the subbase and base courses. The anchor teams will return to finish their work once this has been completed.

Base course installation.

Slip A26

Rehabilitation works: 74/74 permanent UC (Universal Column) piles complete.

The installation of the concrete panels is now complete. Road reinstatement is underway with the wearing course membrane now laid. This is the last layer to be installed prior to asphalting.

The wall is now complete. The wearing course membrane has been installed and ready for asphalt.

Slip A10

The drainage, stabilisation of the existing gabion wall, road reinstatement and guardrail installation are now complete. This section now only requires line marking to be ready for reopening.

Road reinstatement and drainage is complete, and the guardrail has been installed.

Slip A11

This area has experienced movement during the winter months, and our geologists and TARP sensors are continuing to monitor it closely.

Road reinstatement and roadside drainage is complete, and the slip features have been hydroseeded to help minimise the effects of surface water causing erosion.

The final repairs will be completed in the new year to stabilise the slope further, including removing additional loose material and vegetation

Roadside drainage is now complete. The rip-rap rock inset into the concrete is designed to slow the flow of water to prevent it overflowing onto the road.

Slip A12

Rehabilitation works: 38/38 permanent piles complete. 37/38 anchors complete.

The slip repairs are complete, guardrails have been installed and the asphalt has recently been laid.

Now the road surface is complete, the final anchor will be installed in the next month and a smaller anchor rig is available to avoid damaging a large Puriri tree adjacent to the wall.

Asphalt installation is now complete.

Slip A13

Rehabilitation works: 41/41 permanent piles complete. 28/42 anchors complete.

The pavement teams completed the reinstatement of the road from slips A12 to A13 in one continuous section.

The anchor teams will return to complete the last remaining anchors with added protection to ensure they do not damage the new road surface or barriers.

Asphalt installation is now complete.

Slip A27

Slip repair is complete.

The stencil design will be installed over the next month on the wall.

Worker of the month

This month, we’re profiling our Stakeholder Manager, Paul Nicoll (or Paulie as he is better known). Paulie will be a familiar face to many of you as he’s often out and about in the community sharing info about the project at local markets or is the friendly face answering queries. With 20 years of experience in events, arts and placemaking, Paulie has followed in the footsteps of his dad and Opa back into project management and infrastructure working for our Engineer to Contract, Stellar Projects. His creative background equips him with a diverse skill set, allowing him to work across the various areas of infrastructure development and engagement.

Paulie is now a proud Waipapa local, having escaped Tāmaki Makaurau and relocated with his wife and 4-year-old son to be closer to his in-laws. When he’s not on-site, you can find him on a boat, tinkering in the shed, or exploring the outdoors with his family.

Paulie has been instrumental in sharing the project’s journey and has played a key role in responding to inquiries from the public, hapū, iwi, and various organisation with interests in the gorge.

Reflecting on the project, Paulie shares, “The amazing thing about this project is how positive people are about it. Our team has worked hard to share as much as possible, including the technical details without overcomplicating things. The feedback and questions we receive have been incredible—even when I’ve occasionally missed the mark, we’ve been politely corrected, which is something I’ll take away with me.”

In addition to his communication efforts, Paulie has been working diligently in the background, managing project administration as our Engineer's Representative Assistant.

While Paulie will feel a tinge of disappointment when it’s time to move on, he’s genuinely excited about seeing the project completed and the positive impact it will have for the Far North community.

Worker of the month – Paulie Nicoll recording the asphalt installation on Slip A12.

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