TT Géomètres Experts has been involved since 2012 in the construction of a new metro line as part of the Grand Paris Express project: Line 17.
What is the Grand Paris Express?
The Grand Paris Express is a major infrastructure project designed to modernise and expand the public transport network in the Île-de-France region. Several new metro lines are being developed. Among them, the automated Line 17 is one of the most strategic. Extending over 26.5 km with nine stations, it will serve key economic hubs including Saint-Denis Pleyel, Le Bourget, Charles de Gaulle Airport and Le Mesnil-Amelot. The line is scheduled to enter service in several phases between 2026 and 2030.
Safety and precision challenges
TT Géomètres Experts teams play a key role in the project, helping to ensure the accuracy of the structures and the safety of the infrastructure. Line 17 passes through densely populated urban and industrial areas, requiring precise and safe excavation methods:
- Work in dense urban environments: limiting disruption while ensuring the safety of existing infrastructure.
- Work in confined environments: complying with specific protocols and requirements through appropriate certifications and authorisations for working in these environments.
- Geotechnical complexity: managing soil conditions and risks associated with tunnel excavation.
- Coordination with other ongoing infrastructure projects, including other Grand Paris lines, RER lines and motorways.
Carrying out this type of work in underground environments involves specific risks and requires specialised working methods.
Our areas of expertise
The TT Géomètres Experts Paris Nord Groslay office has been involved in the project since 2012, initially carrying out underground utility identification, soil assessment and preliminary surveys. Since construction began in 2019, our teams have been working on the project regularly to verify the compliance of structures and ensure the accuracy of alignments:
- Topographic surveys: Verification of structures under construction, including stations, tunnels and viaducts.
- Automated monitoring: Real-time monitoring of ground and surrounding structural deformation.
- Traverse network control: Measurement and adjustment of reference point networks to ensure millimetre-level accuracy of the structures.
- 3D laser scanning and modelling: Creation of detailed digital models for the analysis of underground structures.
Technology supporting precision
Technological advances have improved the accuracy and efficiency of our work:
- Drones and LiDAR sensors for fast and accurate surveys.
- 3D scanning and BIM for infrastructure modelling and project data management.
- Manual and automated monitoring systems to monitor structural movement and anticipate potential risks.
