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Soletanche Bachy to participate in Toulouse metro extension project

After participating in the construction of the existing Lines A and B, Soletanche Bachy has been awarded the contract to build four work packages, as part of a consortium, for the construction of the new Line C of the Toulouse metro and the Line B Connection.

Line C involves the construction of 27 km of line (including 21 km underground) and 21 stations to link the towns of Colomiers, Blagnac, Toulouse and Labège, passing through the city’s historic center and connecting with the two metro lines, the Linéo bus network and local rail services. At the same time, the Connexion Ligne B (CLB) project on the new Line C completes the existing network, with 2 additional stations for the existing Line B.

With this project, Soletanche Bachy is joining the Toulouse urban area’s active policy of linking its main employment and business areas by means of fast, reliable and economical public transport. The project is expected to reduce car traffic and traffic jams in the Toulouse area (90,000 fewer vehicles each day), encourage the use of soft mobility and improve air quality (28,700 tonnes of greenhouse gases avoided in one year).

Soletanche Bachy will also participate in the environmental efforts promoted by Tisséo, Toulouse Métropole and Sicoval, with a particular focus on tree preservation and the reuse of materials, while ensuring the characterization of excavated material, its sorting, evacuation and treatment in local recovery channels.



The packages in detail 

  • Package 4: 4 new stations, TBM tunnel, 3 ancillary structures and a cut-and-cover tunnel

This contract, carried out by Bessac, Soletanche Bachy France and Soletanche Bachy Tunnels, includes the construction of a 4,160-meter-long TBM tunnel with an internal diameter of 8.50 meters, 4 stations (Montaudran Gare, Ormeau, Limayrac-Cité de l’Espace and Côte Pavée), 3 ancillary structures and their connecting branches to the tunnel, and a 650-meter-long cut-and-cover tunnel at the southern end of the package at Montaudran.

  • Package 5: civil engineering for the northern trench of the access structure to the Garage Atelier des Daturas

This contract, carried out by Soletanche Bachy France (lead), involves the construction of a 230 m long trench, enabling the metro to rise gradually from the underground section to the surface, in front of the future garage workshop.

In all, more than 5,000 m² of 500 to 600 mm thick diaphragm wall will be built from April 2023 using a KS grab workshop, combined with more than 4,000 m3 of civil engineering concrete and 16,000 m3 of earthworks.

  • CLB package: underground works for the connection between Line B and the new Line C

These works, carried out by Bessac (lead) and Soletanche Bachy France, concern the 470 m-long underground section, which includes two transition structures for the entry and exit of the tunnel boring machine (TBM), enabling the excavation of a 250 m-long twin-tube tunnel. This tunnel extends the existing line B from Ramonville station, passing under the Canal du Midi.

The invert and cover slab are built using civil engineering, between diaphragm walls.*

For this project, a KS grab workshop will be used from June 2023 to build the 4,600 m² of diaphragm walls, in thicknesses of 500 and 600 mm, for the transition structures.

The tunnels have very tight radii of curvature and steep gradients at the start and end. These parameters call for the use of a compact machine, namely a point-attack TBM.

  • Package 7: foundation work for a viaduct

As part of this project, carried out by Soletanche Bachy Fondations Spéciales, no fewer than 559 piles (8,700 m of drilling) will be installed under the 130 piers of this 5 km viaduct, which will provide an overhead exit for the metro in the South-eastern part of the route between Montaudran and Labège. The project mainly involves STARSOL® piles (average diameter 1.02 m) at depths of between 15 and 20 m. They will require the mobilization of several workshops. The first piles will be drilled from August 2023, for a total duration of 18 months to the end of 2024.

Several technical constraints along the profile will require special techniques:

  • cased bored piles and mud bored piles on a jetty for 6 piers under nautical conditions with stringent environmental requirements,
  • simple bored piles at limited heights in line with EHV power lines,
  • STARSOL® piles with specific, reinforced procedures near the A61 freeway and SNCF railway lines, which will remain in use.

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