The Mt Messenger Cableway can carry loads of up to 20 tonnes at a time.

Te Ara o Te Ata cableway certified

It’s not every day you see a 16-tonne excavator flying through the air.

But that’s exactly what’s been happening at the site of the future Te Ara o Te Ata: Mt Messenger Bypass, signalling completion of the project’s innovative cableway.

The 1.1 kilometre cableway will transport workers, machinery and materials safely north into the remote heart of the project area.

The structure is a key part of our work to create a safer and more resilient 6km section of SH3 in North Taranaki, while also delivering major long-term environmental gains including pest management over 3,650ha of surrounding forest.

Central North Island Regional Manager of Infrastructure Delivery Rob Partridge says it’s great to have the cableway completed, so the Mt Messenger Alliance can make a fast start to works in the next construction season, starting in September.

Mr Partridge says the cableway helps to minimise the impact of bypass construction on the surrounding environment – one of the project’s main priorities.

“As we close out the current season the team will be using the cableway over the next few weeks - transporting workers and materials for the establishment of areas for storage and the delivery of large machinery such as excavators.

“We’ll get these preparatory works done now so we can really make some good progress after winter in the area north of the project’s 235m tunnel.”

The cableway can carry up to 20 tonnes and rises to 64 metres at the highest point from the valley floor.

It can also be adjusted to serve different purposes, for example – on one trip it might be transporting an excavator, while on the next trip the gondola cabin could be attached to transport people to site.

“In addition to our goal of building a safer, more reliable and more resilient stretch of road, restoration and environmental protection is very much at the forefront of the project.

“The project’s enduring pest management commitment over 3,650 hectares is part of a broader environmental programme for Te Ara o Te Ata, which seeks to leave the area in a better condition than its current state.

“The programme will also deliver large areas of restoration planting, to offset the native vegetation removed to build the road and lessen the effects of construction on the local ecology.

“Thirty-two hectares of forest, wetland and riparian planting will be undertaken, comprising approximately 120,000 plants. A further 100,000-plus plants will be planted along the roadside margins and embankments, with all seedlings grown from locally sourced seed.

"The cableway is allowing us to start work in this area of the new route alignment much sooner than would otherwise have been possible,” says Mr Partridge.

Four of the many kiwi being cared for by the Mt Messenger Alliance ecology team... clockwise from top left: Leonardo, Toa, Donna and Ouenuku.

Caring for kiwi at Mt Messenger

Helping native species thrive once more is among the key goals of Te Ara o Te Ata: Mt Messenger Bypass and nowhere is this more visible than in the project's care for kiwi living in the nearby Parininihi forest.

Since the project's inception, ecologists from the Mt Messenger Alliance have been finding, monitoring and fitting transmitters to kiwi - not only to ensure they are kept away from construction areas but also to help boost their numbers after many years of population decline.

The chief cause of this decline is the high presence of pests in the area, such as rats, stoats and possums - which the Alliance is targeting through ground and future aerial pest management operations over 3650 hectares of adjacent bush.

The combined efforts could see an increase in the local kiwi population of more than 1200 birds over 30 years.

Of late the ecologists' kiwi work has seen the return to the local ngahere of young birds hatched from eggs that were found by the team and taken to offsite sanctuaries - to allow the hatchlings to grow in a predator-free environment and reach the 'stoat proof' weight of 1kg where they are regarded as being large enough to fend for themselves.

Pictured (at the tender age of 24 days) in the top left corner of the image above, Leonardo hatched on 9 October last year and was returned to Parininihi on 17 April after six months of safe growth at the Crombie Lockwood Burrow in Wairakei.

Toa, top right, is another chick hatched from an egg found near the project area and recently returned to Parininihi after achieving ‘stoat proof’ weight at Wairakei.

Hatched on 3 March this year, Donna (bottom right) is currently creched at Sanctuary Mountain Maungatautari (Maungatautari Ecological Island Reserve), and will be returned to the Parininihi area once she is 'stoat proof', likely in the next few months.

And last but by no means least, Ouenuku (bottom left) is a mature female kiwi who has been monitored by the project since 2019. She was caught recently for a transmitter change and a health check before being safely returned to her habitat.

Steel drape mesh and rock bolts are already in place on this cut in the southern half of the new alignment.

Four-pronged approach underway to manage rockfall risk on Mt Messenger Bypass

The Mt Messenger Alliance has a quartet of measures in place to manage the risk and consequences of rockfall from the 19 cuttings of Te Ara o Ata: Mt Messenger Bypass.

All cuttings along the new 6km route are within the 'Mount Messenger Formation', which is typically characterised by soft rock comprising a continuum of silty, fine-grained sandstone to silty mudstone.

The cuttings will range from 5m to 60m in height and 30m to 450m in length. All single slope cuts (i.e. those without benching) will be at an angle of approximately 63 degrees.

Project Design Manager Sharon Parackal says the Alliance and Waka Kotahi agreed the protection measures following a slope risk analysis to identify potential hazards such as rockfalls or landslips, and to assess the likelihood and consequence of such hazards occurring.

"As a result of our analysis we agreed that where cuttings are more than 20m high we'll install steel drape mesh across the full height and width of the cut surface."

The mesh will ultimately cover 60,000m2 of cut face and is ‘open ended’ to allow any rockfall to funnel through into catch ditches beneath.

Catch ditches will run the full length of all the project's cuttings, regardless of the cutting height, and are wide enough to allow a small excavator to move within (generally, a metre deep and four metres wide).

"Where an unstable soil layer is present above the rock cuttings, we’ll install soil nails to maximise stability," adds Sharon.

These works are already in evidence with 580m of drilling completed for soil nails, and mesh installed over 707m² of cut faces.

The fourth measure will be the installation of rock bolts to provide greater stability for areas of cut that are considered more likely to break up. More than 225m of drilling for rock bolt installation has already been completed.

Rock fall trials and assessments continue throughout construction to ensure the set standards are being met and any required adjustments in methodology can be made.

More information

For more information on the Awakino Gorge to Mt Messenger Programme, contact us at SH3@nzta.govt.nz

Visit our website www.nzta.govt.nz/a2mm