Project update

17 July 2025

Excavation of the tunnel's top section is nearing 100 metres.

Construction continues through winter

It might be winter, but there’s plenty of activity at Te Ara o Te Ata - Mt Messenger Bypass project.

We’re working in one of the wettest parts of the region with average annual rainfall of around 2,000mm. This year, July is proving to be particularly wet – with a whopping 97.6mm falling on 3 July alone!

Due to these conditions, bulk earthworks have wound up until the new construction season, but our tunnel and bridge teams are continuing to work at full capacity.

We recently reached a milestone with completion of a temporary staging bridge at the southern base of Mt Messenger. That’s now being used to construct 'Bridge 01', a 125-metre-long structure which has been designed to carry the new road safely over the Mimi Wetland.

The permanent bridge will ultimately lead to Fill 13, a part of the project that's being built up to reach the southern entrance of the 235-metre-long tunnel.

Almost 100 metres in, our tunnellers are making great progress and the 110-tonne road header machine, named Hinetūparimaunga by our iwi partner Ngāti Tama, is currently excavating 2-metre-long cuts into the 6.5-metre-high top section, or ‘heading’.

The surface is being reinforced with shotcrete and rock bolts for stability and we're on target to break through to the north side in October. After that, we’ll begin excavating the bottom section (bench) to form the full tunnel profile – 9 metres high and 13 metres wide.

Planning is well underway for the 2025-26 construction season beginning in October, as we continue delivering this much-needed improvement to the state highway network.

The recently completed 110m temporary staging bridge over the Mimi Wetland.

Bridge achieves key milestone

As mentioned, our Bridge Team recently reached a key milestone, completing a 110-metre-long temporary staging bridge from which we'll construct the project's 125m permanent bridge (currently known as 'Bridge 01') in Zone 6 (as indicated on the map above)

Work began in March on the 17-metre-high temporary structure.

During assembly, the team has gone to great lengths to protect native vegetation, including using a 200-tonne crane to lift ecologists into the bush canopy where they gently moved trees out of the way so piles could be driven with minimal disturbance.

The staging bridge, and all the piles supporting it, will ultimately be removed on completion of the permanent bridge.

Next up is concrete work for the bridge's southern pier, and then the northern abutment – a tricky job that calls for 2,000m³ of earth to be removed via the staging bridge.

Bridge 01 – which will be slightly curved and on a seven-degree incline, supported by raked (angled) piers – is on track for completion by September next year.

Watch our latest project flyover video

We've just published our latest flyover, taking an aerial journey north above the new alignment. Check it out today on YouTube or Facebook. 

Large equipment has been lifted off the site for winter. This 19-tonne dumper truck is riding the cableway over the northern entrance to the tunnel.

Winter 'demob'

With earthworks pausing for the winter we’ve returned some of our heavy machinery to suppliers to avoid it sitting idle over the wetter months.

This demobilisation work has seen some big loads on the cableway out of Zone 3 at the future northern entrance to the tunnel, including 4 x 19-tonne dump trucks, 2 x 14t diggers and one 20t digger.

Traffic management

SH3 Mt Messenger, and the stretches of highway either side, have seen more traffic management than usual of late.

The existing road is outside the project’s remit, but NZTA contractors have been busy this winter clearing a number of slips.

Geotech specialists have also been called in to deal with an underslip on one of the tight turns halfway up the southern side of Mt Messenger.

Slips such as these highlight the vulnerabilities of the existing route, reinforcing the need for a safer alignment that is more resilient and reliable. 

To keep informed on road conditions, please check NZTA Journey Planner or the regional Facebook page.

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.