Deepening experience

New Zealand’s collaborative style and openness to international expertise have been a driving force behind many of our largest infrastructure projects, from early hydropower schemes to recent major tunnels like Auckland’s Waterview Connection, City Rail Link (CRL) and Watercare’s Central Interceptor wastewater tunnel. We’re skilled at taking international expertise and tailoring it to the New Zealand context.

I am an expat myself, having come here to deliver the first Earth-Pressure-Balance Tunnel Boring Machine (EPB TBM) projects like Hobson Bay Tunnel (a wastewater outfall), then on to Waterview and now the CRL. Over that time, I’ve witnessed the local industry evolve, developing homegrown expertise tailored to our unique geological and seismic conditions, particularly Auckland’s volcanic fields.

With future projects such as the proposed tunnels in Wellington and the Waitematā Harbour Crossing in Auckland (where a tunnel is one option), blending local insight with global innovation remains vital. That’s why attending the recent Rapid Excavation and Tunnelling Conference in Dallas, Texas, was such a privilege. I presented a paper co-authored with my colleague, Technical Director Shu-Fan Chau on the use of steel fibre reinforced segments for large-diameter TBM tunnels, offering significant advantages such as reduced construction costs and enhanced durability. This approach was used on Waterview but has developed much further in Australia, on Melbourne’s West Gate Tunnel, Sydney’s Western Harbour Tunnel, and Melbourne’s Northeast Link. It is, however, unusual in the Northern Hemisphere, reminding us that while we often draw from global best practice, Aotearoa is also contributing to it.

Across the 120 presentations, there was a huge amount of knowledge shared, and it’s clear that automation, technological advances and robotics are reshaping the delivery of major tunnelling projects. And all the presentations reinforced the importance of collaboration – multidisciplinary teams working together to respond to unexpected situations.

I could see immediate application for the use of crossover machines (tunnelling machines with a hybrid of pipe-jacking machine and segmental-line capabilities) for constrained sites. The machine can be launched in small shafts, building the first 100m of tunnel using the pipe-jacking feature and then switching to the segmental lining, utilising the initial pipe-jacked tunnel to assemble the machine. There were also presentations on designing tunnels across active fault zones, which is relevant to Wellington.

Subaqueous tunnelling also featured prominently, with techniques like ground freezing and Canadian case studies offering valuable insights – of interest as we explore options for the Waitematā Harbour Crossing. Another presentation showed how automation was being used to accelerate the as-built analysis of the concrete rings that line TBM-bored tunnels. Robotics also featured heavily, and Aurecon is seeing this technology being used already on the Western Harbour Tunnel, where the TBM has robotic tool-changing capability.

The potential for AI is huge; however, the relatively small number of presentations on its use likely reflects the fact that the technology is still new. Some of the applications for AI I can see include interpreting geotechnical data to increase the accuracy of predicting subsurface conditions (which could assist with route planning for tunnels). Also, helping with asset management and predictive maintenance.

As the industry increasingly embraces AI, we must be careful to continue to build engineers’ technical capability, as some challenges will always be too complex for the technology. The best results come from human insight and experience, working together with AI and automation.

As New Zealand enters its next phase of major tunnelling and infrastructure development, looking outward for global thinking and best practice remains essential. But our small scale and distinctive geography also give us the licence to innovate. The techniques we refine here don’t just serve local needs; they can offer valuable insights for the global tunnelling community as well.

Tom Ireland is Major Projects Director, Tunnelling at Aurecon and a Board member of the New Zealand Tunnelling Society.

This article was first published in the September 2025 issue of EG magazine.