Projet Savoie Piemont- Crédit A.Pernet
Projet Savoie Piemont- Crédit A.Pernet

Savoie-Piémont: 190 km of European solidarity from Chambéry to Turin


Together with its Italian partner TERNA, RTE is installing a 190-km line of European solidarity.

This new and entirely underground interconnector will link the Grand-Île substation (Sainte-Hélène du Lac) to the Piossasco substation (Turin). It will bolster exchange capacity and electrical solidarity between France and Italy while also supporting the energy transition. Covering a distance of 95 km on the French side, this underground power line melds seamlessly with existing road infrastructure, thereby preserving the beauty of Savoie landscapes and helping to boost the local economy. Yet another building block in the construction of Europe’s power system.


Key points:


  1. Stronger European electrical solidarity
  2. An impressive technical feat 
  3. Unprecedented environmental coherence
  4. Major local economic spin-offs

40 %
increase in power-exchange capacity between France and Italy
190 km
underground interconnector between France and Italy: RTE’s biggest underground project

500 M€
worth of capital expenditure in France and in Italy, amounting to a total investment of 1 billion Euros
35 M€
worth of economic spin-offs for local businesses

190 km of European electrical solidarity 


Together with its Italian partner TERNA, RTE is installing a 190-km line of European solidarity:

Tracé Savoie Piemont

Spanning a distance of 190 km, this new direct-current interconnector will be the longest of the world’s interconnectors with equivalent levels of power and voltage. It is a unique project that primarily aims to bolster mutual exchange capacities, improve the sharing of resources and facilitate cross-border power exchanges.

The interconnector will bring the maximum exchange capacity between France and Italy to 4450 MW. It will also facilitate integration of renewables into the French and Italian power systems.


Optimal and unprecedented environmental coherence:


The connector melds seamlessly with existing road infrastructure. It runs across 66 km of motorway, 18 km of by-roads, 6 viaducts, 3 tunnels and one underground conduit, whilst also running through the Fréjus road tunnel over a distance of 6.5 km.

This environmental coherence is the result of close coordination between all local players over the period of 2010 to 2012 within the 33 affected communities, as well as close cooperation with road and highway agencies (AREA, SFTRF and the Savoie General Council). In France, it is the first time that an underground interconnector has been combined with a motorway in order to minimise the use of space. This unprecedented approach has even required amendments to the highway code.



An impressive technical feat: 


The new interconnector requires the use of the most advanced technologies in order to transmit electricity over such a long underground distance at such levels of power and voltage.

Spanning a length of 190 km in order to connect the Grande-Île substation (Sainte-Hélène-du-Lac) and the Piossasco substation (near Turin), it is the world’s longest underground line using this type of technology. It has broken the previous record established by the 65-km interconnector between France and Spain, inaugurated in February 2015.


Economic spin-offs across the entire valley:


With 500 million Euros’ worth of capital expenditure being committed in France and the same amount in Italy, the Savoie-Piémont project will considerably boost the local economy. Local manpower and contract companies have naturally been used for work on civil structures and on the converter station.

This has amounted to a total of almost 35 million Euros in economic spin-offs (excluding accommodation and meals) for local businesses with 100 to 150 people being hired over the 6 years of civil-engineering work and 80 to 140 people over the 3 years of work on the converter station. In addition, the 90 000 cubic meters of excavation material have also been used by Savoyard businesses.

  1. Public-opinion survey: Running from the 3rd of January 2012 to the 6th of February 2012 included, the public-opinion survey covered the 33 communities affected by the routing of the line.
  2. Declaration of public utility: In France, the declaration of the line’s public utility was signed on the 15th of June 2012 while that of the switchyard was signed on the 28th August 2012.
  3. Detailed design and start of work: In France, the first batch of work started in April 2015. This included work on a converter station at Sainte-Hélène-du-Lac in the Savoie valley, as well as an entirely underground 95-km line starting from the converter station, running across the Savoie valley to Aiton and then running up the Maurienne valley to the border with Italy, through the Fréjus tunnel.
  4. Commissioning: The project is expected to be commissioned by the end of 2021 at the earliest, following the completion of pre-commissioning tests.