French contractors have been boring tunnels with Herrenknecht technology for almost 40 years. 

Five Herrenknecht machines contribute to the excavation of the new metro line C in Toulouse, France. All are EPB Shields, 9,630mm in diameter, are equipped with some project specific design features like double screw conveyor, sizer or TAP pump.

The project has been divided in four different lots. 

• The joint venture Bouygues-Bessac will work on Lot 4 Montaudran Gare – Saint Sauveur, around 4.3 kilometers.
• The joint venture GIE Material (Implenia and Demathieu Bard) is responsible for Lot 3 Raynal – Saint Sauveur, around 3.9 kilometers.
• Finally the joint venture Eiffage TP/NGE will take care of Lot 1 Colomiers – Laporte Aéroport and Lot 2 Laporte Aéroport – Raynal, in total around 11.8 kilometers.

TBM refurbishment in Thieux

Three machines from the current major project Grand Paris Express – a total of 200 kilometers of new metro for the capital – are now to be reused for the extension of Line C of the metro in Toulouse.

For this project, Herrenknecht’s expertise was not called for in classic rebuilding, but in terms of support, technology and knowledge transfer as the three tunnel boring machines being reused in Toulouse belong to contractor Eiffage Génie Civil. Specifically this means they are stored in Thieux, France, where they were also “reconditioned” as they call it at Eiffage for the Toulouse project.

Eiffage Génie Civil anticipated high groundwater pressure on some sections of the advance. To control this safely, the innovative decision was made to install muck pumps behind the screw conveyor of the EPB Shields. 

In addition, both the shield and the cutting wheel had to be adapted to the smaller diameter in Toulouse compared to Paris. In line with the smaller diameter, the team also installed a new suction plate on the segment erector. Herrenknecht’s control and software expertise was extremely important, as demonstrated by the project-specific adaptation of the control modules.

“Without Herrenknecht, it would  have been very difficult for us to carry out the modifications and reworking  in the given timeframe. Thanks to the collaboration, we were able to complete the three TBMs between May 2023  and February 2024.”
Stéphane Leriche, Materials Director, Eiffage Génie Civil

All five machines are tunnelling in 2025.

Copyright: Hervé Piraud, MRX Communication, Eiffage Génie Civil