New Zealand’s largest transport project
The City Rail Link (CRL) in Auckland marks a major milestone in the development of New Zealand’s transport network. Led by Link Alliance, this project is set to transform the city’s transport system. It involves the construction of two twin tunnels, each 3.4 km long, dug up to 42 metres below the city’s streets. They connect Britomart and the city centre to the existing western line near Mount Eden, thereby improving the connectivity and capacity of Auckland’s rail network.
Carrying out such a project in an urban environment presented a major challenge. The construction of the tunnels and stations required constant monitoring of the structures and their surroundings to ensure the work proceeded smoothly and to manage the associated risks.
A large-scale monitoring system
The Sixense teams set up a monitoring system that was one of the largest ever deployed in New Zealand.
The system included, in particular:
- more than 3,500 monitoring prisms;
- 44 automatic total stations;
- 76 fixed inclinometers;
- geotechnical instruments;
- piezometers for monitoring groundwater.
Thanks to this comprehensive instrumentation, the teams were able to ensure continuous monitoring and tracking of the behaviour of the structures and their surroundings throughout all phases of construction.
Innovative solutions supporting the project
Among the challenges faced was noise monitoring in Auckland city centre. To address this issue, Sixense deployed Nora, its artificial intelligence-based acoustic monitoring solution, capable of distinguishing between construction-related noise and surrounding urban noise pollution. This approach has improved acoustic monitoring on the project.
Other specific challenges were also addressed. Monitoring of the tunnel canopy tubes was carried out by installing an inclinometer unit fitted with In Place (IPI) horizontal inclinometers, ensuring precise monitoring of the structure. Furthermore, monitoring of the North Auckland Line (NAL) led to the establishment of a topographic network with real-time 3D monitoring, enabling the analysis of track deformations and the calculation of various parameters such as torsion, inclination and gradient.
An international benchmark in infrastructure monitoring for Sixense
Through the City Rail Link, Sixense confirms its expertise in monitoring complex infrastructure and its ability to support the most ambitious rail projects worldwide.
