Creating tunnels for transport and utility networks is an increasing part of the infrastructure sector, particularly in urban areas where the amount of space available for building work is decreasing – the options are often limited to building up or building underground. Chris Emery, Business Manager for Monitoring Solutions Europe, explains how technology is being used to ensure sub-centimetre accuracy on major tunnelling projects.

Recent research carried out by TBM actually found that there was a tunnelling project taking place in nearly every country in Europe, with a particular focus on transport networks. When working underground on projects like these, GPS signals can’t be received and companies must use other methodologies for navigation and guidance instead, with optical instruments being the most common. For example, for both large diameter tunnelling machines, such as those used during the build of Metro systems, and micro-tunnelling machines for areas with a smaller diameter, optical instruments are almost always used. 

This approach is showing no sign of diminishing. Optical instruments are a tried, tested and trusted way of working on tunnelling and navigation projects. Topcon has started working with a number of specialist navigation and guidance providers to help with training processes and to integrate our instruments into their tunnelling systems. For example, we’ve recently partnered with Zed Tunnel Guidance, a manufacturer of advanced guidance systems which now exclusively uses our equipment due to the quality of the Topcon Coaxial Laser. Zed Tunnel Guidance now follows a multi-station solution on its projects, using a number of total stations throughout the tunnel for precision accuracy between the machines, even around corners. Watch this video to find out more about the process.

Workflows for companies like Zed Tunnel Guidance are becoming increasingly automated, with Topcon’s total stations making up only one component of the process. The tunnel boring driver follows live navigation data along the planned trajectory, which is constantly updated in line with As-Built Verifications and digital models. There are automated methods being used as part of the initial inspection of the tunnel too, with some companies trialling the use of drones within the tunnel to gather mass data around existing infrastructure assets. 

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