Unlocking the Power of LiDAR and Thermal Drone Technology in Geotechnical and Civil Engineering
Why LiDAR is Changing the Game In…
In early 2023, Auckland’s infrastructure faced a critical challenge when severe flooding caused the collapse of a stormwater culvert beneath Greville Road, a key arterial route connecting Albany to the Northern Motorway. With traffic volumes exceeding 19,000 vehicles per day, the urgency to restore this corridor safely and efficiently was paramount.
Geologix Consulting Engineers Ltd was engaged to provide comprehensive geotechnical support throughout the emergency response and reconstruction. This article offers a technical insight into the challenges faced and the solutions delivered by our team.
Understanding the Ground: Rapid Investigation and Gap Analysis
The foundation of any successful underground infrastructure project lies in understanding the subsurface conditions. Geologix led a focused ground investigation program that included borehole drilling, cone penetration testing (CPT), hand augering, trial pits and groundwater monitoring. These investigations were essential for characterising soil profiles, identifying potential obstructions, and assessing groundwater behaviour.
To strengthen the reliability of the design, we conducted a gap analysis, comparing historical geotechnical data with current site conditions. The challenges we faced arose from the unique setting of the site, positioned in a narrow strip between the a historic closed landfill and the State Highway 1 corridor critical infrastructure. To add to the challenge the available investigation area included many unmarked services including high pressure gas mains, landfill leachate lines and major stormwater pipelines to name a few.
From Field Data to Engineering Strategy
Geologix produced both factual reports, which documented field and laboratory data, and interpretive reports, which translated that data into engineering insights. These reports informed the design of key structural components, including:
- Launch and retrieval shafts for slurry micro-tunnelling. The shafts extended up to 10 m in depth.
- Micro TBM in two drives, highly influenced by the rock mass properties.
- Thrust blocks engineered to resist jacking forces up to 1400 tonnes.
- Settlement mitigation measures and monitoring to protect adjacent infrastructure including the Northern Corridor busway, State Highway 1, Greville Road and the closed Rosedale landfill facility.
Our interpretive work focused on ground stability, bearing capacity, and groundwater drawdown and control, critical factors in designing safe and efficient tunnelling operations beneath a live road.
Designing Permanent Infrastructure for Long-Term Resilience
Geologix was responsible for the design of permanent infrastructure integrated within the shaft environments. This included:
- Manhole chambers up to 10 metres deep, designed to accommodate future maintenance and inspection activities.
- Access structures for safe and durable entry into the stormwater system.
- Permanent thrust blocks and pipe supports, engineered to sustain long-term operational loads and resist jacking forces during installation.
The project also achieved a notable sustainability milestone through the use of low-carbon concrete jacking pipes, developed by Hynds Pipe Systems. This innovation contributed to a 16% reduction in embodied carbon, saving approximately 62 tonnes of CO₂. The adoption of these materials reflects the project team’s commitment to reducing environmental impact while delivering robust infrastructure.
Microtunnelling with Precision: TBM Deployment and Pipe Jacking
A central feature of the project was the deployment of a slurry micro-Tunnel Boring Machine (mTBM) to install a new 2100 mm diameter stormwater pipeline beneath one of Auckland’s busiest arterial roads. The project involved two tunnelling drives—220 m and 50 m, executed from a launch shaft located near the Rosedale Landfill.
The mTBM was selected for its ability to operate in challenging ground conditions with minimal surface disruption. During tunnelling, 2.5 metre-long concrete pipe sections were lowered into the shaft and jacked into place behind the TBM. The jacking frame applied forces up to 1400 tonnes, requiring precise thrust block design and alignment control. Geologix supported this process by monitoring ground and groundwater movement in real time to ensure safe and accurate installation. Reporting on trigger and action items during the construction process.
The TBM operation was supported by a slurry system that managed spoil removal and face pressure, critical for maintaining tunnel stability. The confined space environment also demanded robust safety protocols by the contractor McConnell Dowell. The combination of advanced tunnelling technology, sustainable materials, and collaborative engineering made the Greville Road project a benchmark for emergency infrastructure delivery.
Monitoring and Contingency Support During Tunnelling
Geologix was responsible for implementing and managing the real-time ground movement monitoring throughout the tunnelling phase. This included the specification of settlement markers and instrumentation to detect any surface or subsurface displacement.
Our team also provided groundwater monitoring and reporting during the TBM operations with daily to weekly monitoring, enabling the construction team to respond quickly to any anomalies. This monitoring regime was not only a safeguard, it was a proactive risk management tool that helped maintain control over tunnelling operations in a complex and sensitive environment.
In parallel, Geologix developed and maintained a contingency support framework, ready to respond to unexpected ground behaviour, obstructions, or groundwater inflow. Our engineers remained on-call to interpret monitoring data and advise on adjustments to geotechnical parameters, ensuring safety and continuity throughout the works.
A Collaborative Success
The Greville Road Emergency Works project was delivered under intense time pressure, with multiple stakeholders working in close coordination. Geologix worked closely with other engineering consultants, Healthy Waters, McConnell Dowell, and other delivery partners to ensure the success of the project.
Other successes of the project included:
- Low-carbon concrete pipes, reducing emissions by 60 tonnes of CO2, equivalent to 122 car trips from Cape Reinga to Bluff.
- Re-use of equipment from other projects including the mTBM plant.
- Concrete waste and aggregates were recycled or reused, in particular for shaft backfill under guidance and specifications from Geologix.
- Reuse of stormwater equivalent to 650,000 litres, eliminating 22 heavy vehicle trips to landfill or 360 kg of CO2.
- Solar powered monitoring systems.
- 7000 native trees planted along the site.
This collaboration enabled rapid decision-making, integrated design reviews, and seamless execution across disciplines. The project has since been recognised as a finalist in the 2025 Āpōpō Asset Management Excellence Awards, highlighting its innovation, sustainability, and collaborative delivery.
