Project update

26 February 2025

The 235-metre tunnel is beginning to take shape.

Going underground

This month’s big news at Te Ara o Te Ata is the start of tunnelling.

We broke ground on the 235-metre tunnel at the start of February and in a matter of days the shape of the future passageway was clear to see.

Teams will work two shifts per day, excavating the 9m-high, 13m-wide tunnel, and securing it with shotcrete (sprayed concrete) and rock bolts for stabilisation and support.

Following approximately 11 months of excavation, attention will turn to other structural elements like the portals and egress passage, with fitout of electrical components to follow before road opening.

There will also be the application of cultural elements acknowledging tūpuna (ancestors) of the project's iwi partner Ngāti Tama, the traditional guardians of the northern gateway to Taranaki.

The bulk of the approximately 25,000 cubic metres of material to be removed from the tunnel will become part of the slope leading to its southern entrance, with anything not suitable being used to build up nearby land. None of the excavated material will leave the rohe of Ngāti Tama.

Hinetūparimaunga leads the way

This month’s start to tunnelling was the result of years of preparation.

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.

The 235-metre tunnel will be excavated in two stages: the ‘top heading’ first, followed by the ‘bench’.

Fresh from the City Rail Link in Auckland, a 110-tonne road header was shipped to Taranaki and refurbished for the job. A rotating drill head cuts through the earth, with a conveyor belt feeding spoil to trucks for removal.

The road header is the most efficient and cost-effective option for excavating a tunnel of this length in this location. 

In keeping with tunnelling tradition, the road header has been given a female name, gifted by mana whenua Ngāti Tama: Hinetūparimaunga, named after the atua - guardian of mountains, cliffs, and hills in Māori creation lore.

As depicted in a design on the cutting-head boom, she extends her limbs to brace and protect within the passageway, symbolising strength and shelter.

A yellow background symbolises light at the end of the tunnel, another milestone that we’re looking forward to achieving.

Major cut completed on approach to southern bridge

Away from the tunnel, we’ve also made a strong start to 2025 across the whole project footprint, making the most of a long-awaited dry spell in northern Taranaki.

On the southern side of Mt Messenger, we’ve hit another milestone, excavating almost 50,000m3 from ‘Cut 14’ since October 2024 to open the way to the site of the project's 125m bridge.

Temporary staging will soon be erected so we can begin work on the permanent bridge structure, which will carry the road safely over a wetland.

Picture above, the completed Cut 14 is 38m high and 130m long. It will have steel drape mesh installed, allowing any rockfall to safely funnel down into catch ditches for easy clearance.

On the northern side, work has continued to prepare Cut 11 where the tunnel will emerge and Cut 10, which will allow the new road to curve smoothly away from Mt Messenger towards Waikato.

The graphic below shows the project's 'construction zones', incorporating key sites including both bridges, the tunnel and the site headquarters at the southern foot of Mt Messenger. Also shown is some of the project's 3,650-hectatre pest management area.

A bumper season for kiwi conservation: safe eggs, healthy chicks, and fresh transmitters

The kiwi breeding season has continued to be a bumper one!

Since the start of this year, our kiwi experts have lifted five fertile eggs for hatching at the Gallagher Burrow at Wairakei near Taupō and the National Kiwi Hatchery in Rotorua.

Fourteen young kiwi are being creched at Wairakei and they’ll be released in Parininihi once they’re over 1kg and considered large enough to fend off predators such as stoats.

Between now and the end of May, the 16 monitored kiwi in the project area will be caught to have their transmitters changed.

Kiwi Diane became a minor celebrity when footage of her nighttime activities hit social media last month. She now has a fresh transmitter which enables us to track her movements and condition.

When attached to males, the transmitters also provide valuable information to determine when they’re incubating and when it’s safest to uplift eggs (usually 60 days after laying).

Currently there aren’t any occupied nests within the construction area, but each day before work begins, kiwi with transmitters attached are checked by an ecologist using telemetry gear and a kiwi dog makes sure the area is clear as an extra precaution to help keep them safe.

Treading as lightly as possible on the land has been one of the project’s core goals and we’re proud of the efforts being made to safeguard local wildlife. With more kiwi set to return to the wild in the coming months, we’re showing how construction and conservation can go hand in hand by combining expert monitoring, careful site practices, and strong partnerships.
 
Every successful hatch and safe release is a step toward strengthening the kiwi population in Parininihi for future generations.

Kiwi Diane became a minor celebrity when footage of her nighttime activities hit social media last month.

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.