Project update

10 November 2025

Construction continues at multiple locations

The 2025-26 earthworks season is underway, and our team is busy on multiple sites throughout the project footprint.

The highlight of the last few weeks has been the successful breakthrough of the 235-metre-long tunnel (pictured above and below), after eight months excavating the 6.5-metre-high top section, or ‘heading’. Our tunnellers will now begin the bottom section (bench) to form the full tunnel profile – 9m high and 13m wide.

Elsewhere, the cableway is being put to good use ferrying equipment and materials into 'Fill 12', which will lead to the northern entrance of the tunnel. 

We’re also working on the southern approach to the tunnel. Much of the material excavated during tunnelling is being used to build up the new roadway. We’re also installing a new sediment retention pond in this area, to further protect the surrounding environment during construction.

Further south, the 125m bridge is taking shape to carry the new road across a gully feeding the Mimi wetland. A 110m temporary bridge is being used to construct abutments that will hold the finished deck on either side of the gully.

We’re keeping a wary eye on the sky with a lot of rain in October, but we’re looking forward to summer and another successful construction season, adding to the 300,000 cubic metres of earthworks completed so far.

The highly anticipated top heading breakthrough marked a significant step forward for the bypass project. The excavation of the bottom section is targeted for completion by March.

Tunnellers beat challenges to break through

Last month’s breakthrough of the tunnel was a proud moment for the team at Te Ara o Te Ata - Mt Messenger Bypass.

Specialist tunnellers have been on site since 2023, working alongside designers, planners and surveyors on a comprehensive strategy to handle the challenges of the rugged Mt Messenger formation.

Excavation on the 13m-wide, 6.5m-tall top heading began in February, with each new cut secured by layers of shotcrete – steel fibre reinforced concrete sprayed at high pressure, stabilising the rock face – along with rock bolts for extra stability.

Tunnel Manager Sam Tang says progress on the job has been both steady and rewarding: “We’ve made good headway, particularly in refining our rock bolting system to overcome some early challenges. This kind of adaptive engineering is what makes tunnelling so interesting.”

This job is particularly notable as the first permanent shotcrete-lined road tunnel in New Zealand – a unique and technically significant milestone.

“Typically, road tunnels use precast concrete segment rings for lining, or shotcrete is applied as temporary support,” Sam says. “That’s followed by an in-situ concrete lining as the permanent structure.”

At Te Ara o Te Ata, the project made the decision to use a permanent shotcrete liner – a choice driven by both engineering innovation and site-specific challenges. This approach meets elevated performance standards, including long-term durability and fire engineering requirements, ensuring the tunnel will be just as safe and robust as traditionally lined tunnels.

“Permanent shotcrete lining allows us to maintain the final tunnel profile more efficiently, while still achieving the same structural integrity and safety outcomes,” says Sam. “It’s a proven method internationally, and we’ve tailored it to meet New Zealand’s standards and conditions.”

With the top heading achieved, Sam and the team remain focused on innovation and safety as they work on the 2.5m tall bottom section, or bench. “We’re always striving to improve efficiency while maintaining high standards,” he says.

Protecting our waterways

Delivering an essential infrastructure project while protecting the mauri of the land and waterways is a focus at Te Ara o Te Ata - Mt Messenger Bypass.

The project has come through a wet and windy winter, with our award-winning erosion and sediment controls (ESC) handling more than 16 ‘trigger events’ – periods of heavy rain requiring best practice approaches to prevent runoff from our sites impacting waterways.

An essential part of managing our Fill 12 work area is a sediment retention pond (SRP, pictured above) that began operating earlier this year on the northern side of Mt Messenger. An SRP is a temporary pond for collecting rainwater runoff, where chemical treatment helps sediment sink to the bottom while clean water is discharged.

Designed to manage runoff from a 5-hectare catchment, the 1600m³ Fill 12 SRP is two-thirds the size of an Olympic swimming pool. Built using 15,000m³ of fill material, the SRP will be in place for more than three years, so it has been critical to ensure that it’ll be effective for the longer term.

We’ll build on the success of the Fill 12 SRP this construction season, when we start to install a similar pond in Fill 13, on the southern side of Mt Messenger in the area leading up to the 235m tunnel.

Preparations are underway for this new 380m³ SRP, which will handle runoff from a 2.1ha catchment area until we finish the road alignment.

SRPs are an important part of our erosion and sediment controls that help safeguard the unique northern Taranaki ecology, as the project treads as lightly as possible on the whenua.

Rhi hatched recently at a specialist facility, from an egg uplifted by project ecologists.

Helping our national bird from hatch to release

While we’re delivering a safer and more resilient road, our ecologists are continuing their busy programme of mitigation and restoration.

We’re in the midst of a big kiwi breeding season, monitoring 18 kiwi so that we can safely uplift eggs for hatching in specialist facilities at Wairakei and Rotorua. The team will be busy lifting eggs over the next few months with most of the monitored males either sitting or having completed their first clutch.

Rhi (above) is among recent hatchlings and will be reared to a stoat-proof weight (over 1000g) before being returned to the pest-controlled western Parininihi. Flit (below) is a recent returnee and is now running about in the wild living his best life.

We’re fortunate to have some top kiwi specialists on our team, from kiwi dogs that sweep construction areas to make sure no kiwi are present before work starts, to accredited handlers who are skilled in all aspects of safeguarding this national taonga.

Our expert ecologists work together with mana whenua and project partner Ngāti Tama, actively monitoring and protecting flora and fauna. Only 5% of kiwi chicks make it through to adulthood in areas without predator control, so the ongoing partnership is giving local kiwi a much improved chance of survival.

Top: Work to repair underslip. Bottom: Repair complete.

SH3 Mt Messenger underslip repaired

Repairs to an underslip on SH3 Mt Messenger were completed in October, following damage caused by heavy rain over winter.

Despite challenging weather and ground conditions, crews worked hard to keep the programme on track. 

Thank you to the repair team for their great work and for the travelling public's patience and understanding while this important work was carried out.

SH3 Mangapepeke culvert replacement projects

NZTA will soon be replacing two ageing culverts on SH3 north of Mt Messenger.

The team will be replacing the Mangapepeke No.1 and No.2 culverts near Ahititi with new modern structures to ensure the highway remains resilient, reliable, and efficient for people using the road for years to come.

Workers will be getting underway with enabling works in late November, with the main earthworks and culvert replacement work being planned to start in January 2026.

Due to deep excavation works required, a full road closure of SH3 in the area is being planned for between 16 and 20 January.

The combination of deep open trenches, heavy machinery and space requirements means it is not safe or practical for road users to travel through the site during the 5-day closure while this work is underway.

The road, between Okau Road in Ahititi and the Uruti Community Hall, will fully close for 5 days, from 12.01am on Friday 16 January to 11.59pm on Tuesday 20 January to allow for the work to take place.

NZTA is coordinating this work alongside the regular summer road renewals season and other works on SH3, so road users can expect to see lots of activity between New Plymouth and Hamilton this summer.

More information can be found here and you can keep up to date with this project via this webpage: nzta.govt.nz/sh3-mangapepeke-culvert-replacement

More information

For more information on Te Ara o Te Ata: Mt Messenger Bypass, please visit our website, email SH3@nzta.govt.nz or call 0800 BYPASS.