10 years of Implenia France

One of Implenia France’s first major projects was the extension of Line 11, a major construction project in the Greater Paris area.

The project involved the construction of a 3 km-long tunnel, a 200-metre-long covered cutting and four stations: Liberté, Place Carnot, Hôpital Nord and La Boissière. Two stations were excavated using conventional construction methods, whilst the other two were built using the cut-and-cover method with diaphragm walls. The project also included three ventilation shafts and various ancillary buildings.

The tunnel boring machine, named Sofia, was named in honour of Sofia Amalou, a mobile staff member at RATP.

Further information on this project: Extension of Métro Line 11, Lot GC01, Rosny-sous-Bois, Paris
 

With the T2C contract, Implenia France embarked on a particularly ambitious project: a 4.7 km tunnel between Noisy-Champs and Bry-Villiers-Champigny, supplemented by a 2.2 km-long branch tunnel, the maintenance and logistics station (SMR), a large underground junction structure and several intermediate shafts.

Two tunnel boring machines were deployed almost simultaneously for this project: the first to reach the maintenance site, the second for the main tunnel of Line 15. The two tunnel boring machines were named after two women: Steffie-Orbival, in homage to the first woman to operate a diaphragm wall cutter; and Malala, named in honour of Malala Yousafzai, the 2014 Nobel Peace Prize laureate.

More information on this project: SGP – Linie 15 Süd, Los T2C 

To meet the requirements of the Grand Paris Express and the RATP, Implenia France also set up its own production plant for tunnel segments. The plant in Limoges-Fourches comprises a covered hall measuring 7,000 m² and a storage area of 12,000 m².

Thanks to a CBE carousel with six ring moulds, it can produce up to 105 tunnel segments per day. A humidification system also enables the simultaneous control of temperature and humidity for five rings.

The success of this facility prompted Implenia to install a second carousel in order to serve further contracts from the consortium and new clients.

More information on this project: Tübbingwerk Limoges-Fourches

With the UA53 HI LUMI Project Point 5, Implenia France demonstrated its ability to work in a particularly challenging environment: the excavation of an underground tunnel for technical and electrical installations such as power converters.

The works involved the construction of a 70-metre-deep shaft, a 46-metre-long cavern, a 300-metre-long main gallery, four connecting tunnels and five above-ground buildings.

The proximity to the operational CERN facilities required particularly strict vibration limits. The shaft and galleries were therefore excavated using conventional methods without explosives, so as not to disrupt the highly sensitive scientific experiments currently underway.

More information on this project: CERN – Galerie UA 53 

Work continued in Lyon with the extension of Metro Line B between Oullins railway station and Saint-Genis-Laval – Hôpitaux Sud station. The project involved excavating 2.5 km of tunnel at a depth of more than 20 metres, as well as the construction of two new stations.

The greatest technical challenge lay in the geological conditions encountered: particularly permeable alluvial deposits, which is why a variable-density tunnel boring machine was chosen. Added to this were stringent requirements for settlement control. A laboratory set up specifically for the project developed a new technical slurry that enabled settlement to be controlled in this complex ground.

The tunnel boring machine was christened ‘Coline’ – after its young godmother, who was then in her first year of a BTS degree in public works.

More information on this project: Linie B der Métro Lyon & Verlängerung der Métro B – Hôpitaux Lyon Sud – GC01

To support the extension of Metro Line B in Lyon, Implenia France set up a second production facility for tunnel segments in Ambronay.

This 3,000 m² plant, supplemented by a 13,000 m² storage area, featured an automated carousel with a production capacity of 175 tunnel segments per week.

As in Limoges-Fourches, a humidification system enabled the temperature and humidity of the rings to be controlled.

More information on this project: Tübbingwerk Ambronay, Lyon

Another milestone for Implenia France was Lot 17-1 of the Grand Paris Express.

The construction project comprised 6.1 km of tunnel boring in two phases, 750 metres of covered cutting and the construction of two main stations.

Up to 300 construction workers were employed on this project – a testament to the scale of the human resources required to deliver such an infrastructure project.

The tunnel boring machine, named ‘Florence’, was named after its godmother, Florence Croquant, a member of the site team. This choice also underlines the commitment to raising the profile of women in technical professions and the construction industry.

More information on this project: U-Bahn Linie 17.1 – Paris Grand Paris Express

In 2021, Implenia France continued its work on the Lyon–Turin Base Tunnel project as part of Lot CO08. Working from the Villard-Clément portals, the teams are excavating and lining the two tubes of the base tunnel over a distance of 2,839 metres towards Saint-Martin-la-Porte, including 509 metres of tube lining in previously consolidated ground.

The construction site also includes cross-passages between the two tubes, six niche units, the installation of a conveyor belt for material removal, and the construction of a covered cutting.

Given the heterogeneous, complex and unstable geology, the decision was made to use conventional tunnelling methods.

More information on this project: TELT, CO08 – Villard-Clément 

Implenia France’s story continues in Toulouse – with Lot 3 of the future Metro Line C. The project involves the tunnelling of a 3,814-metre-long tunnel with a diameter of 10 metres in a densely built-up urban environment, as well as foundation, earthworks and civil engineering works.

The teams are also constructing four underground stations at depths ranging from 24 to 39 metres, as well as a ventilation shaft.

And because Implenia France’s tunnel boring machines often have a story of their own, this one is no exception: Marie-Thérèse de Villeneuve-Arifat is named after a Marquise and former champion of the Jeux Floraux de Toulouse, a historic cultural institution in the city. The tunnelling was completed on 14 August 2026.

More information on this project: Métro Toulouse Linie C, Los 3

To support the work on the Toulouse Metro Line C, in particular on Lot 3 – which is being carried out by Implenia France – and on Lot 4, a new production facility for concrete rings has been set up in Toulouse.

The site was designed for the production of very low-carbon fibre-reinforced concrete segments and was sized to produce around 30,000 segments. This production enabled the lining of almost 8 kilometres of tunnel – corresponding to the 3,814 metres of Lot 3 and the 4,160 metres of Lot 4.

This is yet another example of Implenia’s ability to develop industrial solutions tailored to the requirements of major projects – whilst integrating measures to reduce the carbon footprint right from the planning and production stages of the structures.