3D innovation for the tunnels of tomorrow

At the 2026 World Tunnel Congress in Montreal, Arnaud Hochart and Guillaume Lefrançois, geology and underground mining experts at Implenia, presented an innovation they had developed in collaboration with the teams at the TELT CO08 construction site: the use of 3D photogrammetric models generated directly at the tunnel face to improve geological mapping and the management of underground works.

Developed on the basis of a solution already used in our Swiss projects and subsequently adapted to the operational requirements of the Lyon–Turin project, this approach demonstrates in concrete terms how digital transformation is advancing in tunnelling.

A new approach to geological surveying at the tunnel face

In tunnels excavated using blasting techniques, monitoring the geological conditions at the tunnel face is crucial for adjusting temporary support measures and ensuring the safety of the tunnelling operation.

Traditionally, these analyses are based on manual surveys carried out by geologists on site: sketches, direct measurements and visual interpretations. This is a tried-and-tested method, but one that has certain limitations, particularly in terms of safety, reproducibility and data consistency.

To address these challenges, the teams at the TELT CO08 construction site integrated a photogrammetry solution that enables the rapid creation of a georeferenced 3D model of the exposed working face.

The principle: a series of calibrated photographs of the working face is taken to reconstruct an extremely detailed 3D model that can be used directly for geological and geotechnical analyses.

An innovation for real-world conditions on the construction site

One of the biggest challenges was to integrate this technology without slowing down the drill-and-blast tunnelling cycle, where every minute counts. Photogrammetric surveys are now carried out in less than five minutes, using 30 to 50 photographs taken immediately after excavation. This speed makes it possible to integrate the survey into ongoing construction processes without disrupting tunnelling operations.

The teams also developed specific solutions tailored to the requirements of tunnelling:

• a laser-based system for georeferenced surveying without the need for target markers at the tunnel face,
• autonomous high-performance lighting,
• and a processing workflow that is compatible with existing geotechnical tools.

The result: realistic, precise and easy-to-use 3D models that facilitate an understanding of geological structures.

From a mapping tool to a strategic tool

Originally introduced to improve geological mapping, photogrammetry quickly demonstrated a much broader potential.

Today, 3D models enable:

• the analysis of discontinuity families,
• the identification of rock wedge configurations,
• the improvement of structural analyses,
• the early detection of certain geological anomalies,
• support in the adaptation of support measures,
• the verification of the correspondence between planned and actually installed support,
• the assessment of over-profiles and excavated volumes.

A specific example presented at the WTC concerned the early identification of a large shear zone near a future cross-cut. By integrating the geological data into the project’s 3D model, the teams were able to anticipate difficult conditions and prepare appropriate support measures even before the zone in question was reached.

A building block on the path to the tunnel’s digital twin

Beyond geological monitoring, this innovation is gradually contributing to the creation of a genuine digital tunnel environment.

The 3D models are now being used to:

• create more consistent as-built documentation,
• improve quality control of the shotcrete,
• analyse excavated volumes,
• facilitate collaboration between site supervision, geology and management,
• and integrate geotechnical data into the project’s BIM environment.

This digital continuity also opens up new possibilities for maintenance, immersive visualisation and the asset management of underground infrastructure.. 

A concrete example of digitalisation in tunnelling

In their presentation at WTC Montreal 2026, Arnaud and Guillaume demonstrated how a technology that originated from a specific operational need on the construction site can become a collaborative and strategic tool for large-scale underground projects.

This approach highlights the growing importance of digital technologies in tunnelling:

• better safety,
• higher data quality,
• decision support,
• optimisation of resources,
• and the preservation of knowledge throughout the entire life cycle of the structures.

Developed directly from practical experience on the construction site, this approach demonstrates how an operational innovation can gradually evolve into a strategic tool for the tunnels of tomorrow.