Project update

2 February 2026

Tunnellers celebrate completion with the 110-tonne roadheader machine.

Progress update – tunnel completed!

Refreshed after a well-deserved Christmas break, our team has made a cracking start to 2026, across all our work zones.

First up, a major milestone saw completion of the project's 235m tunnel on 28 January. The tunnel team have done a great job in the challenging Mt Messenger formation and are currently in the process of wrapping up their operations.

The end of tunnelling will see the departure of the project’s iconic cableway, as we’ll now be able to use the tunnel to move machinery and materials into the northern part of the bypass alignment – something the cableway has made possible for more than 3 years.

There’s been extensive planning to ensure a safe and efficient removal process and we'll be starting to disassemble the tower, cables and associated infrastructure in the coming weeks.

Meanwhile, earthworks for the north and south abutments (concrete substructures that will connect the bridge to the land) have been completed at each end of the project's 125m bridge.

The recent focus has been on the south pier and abutment, installing micropiles for the pier and concreting the formwork which will anchor the bridge deck to the road. As shown in the image below, the bridge has two angled piers, or legs, at each end that will minimise impact on the wetland below and a tributary of the Mimi Stream.

2026 will be an exciting year at Te Ara o Te Ata - Mt Messenger Bypass and we’re looking forward to keeping you updated on our progress.

The tunnel team take a breather outside the northern tunnel portal following the completion of excavations and lining on 28 January.

Light at the end of the tunnel

Excavation of the tunnel bench, or bottom section, concluded the final chapter of one of the project’s most technically complex phases.

The tunnel is a vital part of the new bypass, carrying State Highway 3 safely beneath the summit of Mt Messenger and providing a more comfortable driving experience with a less narrow, winding and steep alignment than at present.

The 9m-high x 13m-wide tunnel is the first in the country to have its permanent lining applied during excavation, with steel fibre-reinforced shotcrete sprayed at high velocity to provide immediate and enduring stability.

Tunnelling through the Mt Messenger Formation has required careful planning and adaptability. The papa sandstone that forms the mountain behaves differently to harder rock found elsewhere, demanding a cautious approach early on.

As the tunnel advanced, detailed surveying and constant monitoring allowed the team to modify their approach, optimise excavation methods, and safely accelerate progress.

This ability to learn, adjust, and innovate has been a defining feature of the tunnel works. From refining rock bolting designs to fine-tuning daily excavation cycles, the team combined engineering expertise with on-the-ground problem-solving to keep work moving safely and efficiently.

Equally important has been the collaborative Alliance model that underpins the project. Designers, surveyors, tunnellers, safety specialists, and environmental teams have worked side by side throughout the process, sharing knowledge and solving challenges collectively.

This integration has been a significant factor in delivering such a complex piece of national infrastructure.

With tunnel excavation and lining complete, the focus will turn to portal structures, services installation, and completion works that will ready the tunnel for its role in improving safety, resilience, and reliability for the region.

The tunnel stands as a testament to teamwork, problem-solving, and a commitment to achieve lasting benefits for Taranaki.

Farewell to a landmark

One of Taranaki's most striking features will soon disappear from the top of Mt Messenger.

The project's cableway has played a pivotal role on the job, but with the tunnel’s completion, the team will soon have direct access to works on the northern side of the mount.

Extensive planning has gone into a cableway demobilisation programme scheduled to begin in early March and take around six weeks to complete.

The complex process will be carefully sequenced with support from a specialist crew from Austria. To safely remove the main 60mm cable, the team will first construct a temporary 18.5m-high tower partway up the gully north of the tunnel. This will support the cable’s weight while it’s progressively lowered using three cranes and two winches.

Hardware will be removed from the northern anchor point, while at the southern end of the cableway both steel components and concrete will come out. This area will later be excavated as part of Cut 13, a 55-metre-high cutting on the new road alignment.

The cableway was an award-winning innovation installed in 2022 to enable earthworks in the most inaccessible part of the project footprint. It was the first time a cableway had been used for road construction in New Zealand and quickly became a familiar landmark on the Mt Messenger journey.

Capable of transporting up to 20 tonnes of equipment per trip, or 8 people via a gondola, the system has provided vital access to the project’s deepest fill area, which will use 600,000m3 of earth from project excavations to build up a smooth driving surface immediately north of the tunnel

The cableway has done a fantastic job helping deliver the new road and we’ll be sad to see it go, but we’re looking forward to a successful demobilisation as one of our key milestones for 2026.

Large pipes will allow passage of aquatic wildlife below the future bypass.

Keeping water and wildlife moving below

When the new bypass is finished, aquatic wildlife will be able to go about their business deep below the surface thanks to a carefully engineered system of giant pipes.

Sixty-nine 2.5m diameter pipes will be installed for the 240m-long Culvert 15 north of the tunnel, with a further 25 pipes of 2m in diameter earmarked for the 140m-long Culvert 16, south of the tunnel.

Together, they form critical links in the project’s drainage and environmental protection systems.

A roading culvert is a drainage structure built under a road allowing water to flow from one side to the other, preventing flooding, erosion and damage to the road surface while also supporting the heavy loads of vehicles overhead.

At Mt Messenger, these culverts must also meet strict environmental requirements. Each pipe is fitted with a built-in fish passage system, using specially designed baffles to slow water flow and create resting zones. This allows native fish and other aquatic life to move upstream and downstream, even during periods of high flow.

Installation is a precise operation. A trench is excavated, then the pipes are placed using diggers. The pipes are carefully aligned and joined to form a continuous channel. Protective layers of gravel and engineered earth fill are added around the pipes to stabilise them and prevent sediment entering the waterway.

In the case of Culvert 15 north of the tunnel, the pipes will eventually be covered by earth fill measuring 30m in height, sitting well beneath the finished road but accessible at each end for inspection and any necessary maintenance.

By combining robust engineering with environmental safeguards, the project is ensuring Mt Messenger’s waterways remain healthy long after road construction is complete.

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.