Toulouse metro tunnelling to start soon

12 February 2024

The team responsible for the extension of Toulouse’s metro Line B is preparing to launch the TBM.

A consortium of Bessac, GTM Sud-Ouest TP GC and Soletanche Bachy France has the contract for the construction of the underground structures of Connexion Ligne B (CLB). These include two single-tube tunnels, each 250m long and with an internal diameter of 4.66m, which form a double metro track with a reduced right-of-way under the Canal du Midi.

The TBM, named Clémence Isaure, will install 2,850 tunnel segments. The segments will be made from Bessac’s low carbon Exegy concrete, using locally sourced metakaolin. Bessac says for that, thanks to the support of Vinci Construction and Soletanche Bachy’s materials departments, for the first time 55% of the cement clinker used in the concrete has been replaced by a mixture of limestone filler and metakaolin.

Image credit: Laurent Barranco

This reduces the CO2 emissions linked to the concrete used for the segments by around 40% compared with traditional concrete.

Bessac says the Exegy concrete meets client performance requirements in terms of strength class (C40/50), exposure class ensuring durability of reinforcement (carbon dioxide attack) XC2 and chemical attack XA1.