Strictly speaking, the LGV's or TGV lines.
The most recent ones built are (2016) (near Nancy) - Strasbourg, (2017) Le Mans - Rennes, (2017) Tours - Bordeaux, (2018) Avignon - Montpellier, with none under construction, as far as I've been able to find out.
Barreau de Massy (Massy Interconnection), a connection near Paris between the LGV Sud-Est (Southeast: Lyon-Marseille) and the LGV Atlantique (Atlantic: Tours-Rennes, LeMans-Bordeaux), a connection much like the existing one between the LGV Sud-Est and the LGV Nord (North: Lille-Chunnel/Brussels).
This will enable bypassing Paris for trains between (1) W and SW France and (2) NE and SE France, much as the present interconnection enables trains between NE and SE France to bypass Paris.
Paris - Rouen - Le Havre. It will extend westward from Paris's Haussmann-Saint Lazare station. Another rail construction project is already going on there, the westward extension of the regional-system RER E line from there to some west-side stations of the RER A: Porte Maillot, La Défense-CNIT, and Nanterre-la-Folie.
Bordeaux-Toulouse. The national gov't has committed most of the funding for that 222-km line.
Marseille-Toulon-Cannes-Nice. Funding has been committed from the EU, the national gov't, and local gov'ts. It will be a mixture of new line sections and upgrades of existing ones, like a new underground station at Marseille Saint Charles and tunnels elsewhere.
Montpellier-Béziers-Perpignan. It will start with an extension of the existing line from Montpellier to Béziers, with a later extension to Perpignan. That will make continuous high-speed trackage on both sides of the Perpignan-Figueres tunnel in the Pyrenees mountains at the France-Spain border.
The most recent ones built are (2016) (near Nancy) - Strasbourg, (2017) Le Mans - Rennes, (2017) Tours - Bordeaux, (2018) Avignon - Montpellier, with none under construction, as far as I've been able to find out.
- TGV - Wikipedia
- France Expands TGV High-Speed Rail to Move Beyond Paris - Bloomberg
- The four high-speed lines that France considers | RailTech.com
- French government commits €4bn to Bordeaux – Toulouse HS project | International Railway Journal
- Funding agreed for new €3.5bn Côte d’Azur line | International Railway Journal
- RER E Line Extension for Rail Network, Paris, France
Barreau de Massy (Massy Interconnection), a connection near Paris between the LGV Sud-Est (Southeast: Lyon-Marseille) and the LGV Atlantique (Atlantic: Tours-Rennes, LeMans-Bordeaux), a connection much like the existing one between the LGV Sud-Est and the LGV Nord (North: Lille-Chunnel/Brussels).
This will enable bypassing Paris for trains between (1) W and SW France and (2) NE and SE France, much as the present interconnection enables trains between NE and SE France to bypass Paris.
Paris - Rouen - Le Havre. It will extend westward from Paris's Haussmann-Saint Lazare station. Another rail construction project is already going on there, the westward extension of the regional-system RER E line from there to some west-side stations of the RER A: Porte Maillot, La Défense-CNIT, and Nanterre-la-Folie.
Bordeaux-Toulouse. The national gov't has committed most of the funding for that 222-km line.
Marseille-Toulon-Cannes-Nice. Funding has been committed from the EU, the national gov't, and local gov'ts. It will be a mixture of new line sections and upgrades of existing ones, like a new underground station at Marseille Saint Charles and tunnels elsewhere.
Montpellier-Béziers-Perpignan. It will start with an extension of the existing line from Montpellier to Béziers, with a later extension to Perpignan. That will make continuous high-speed trackage on both sides of the Perpignan-Figueres tunnel in the Pyrenees mountains at the France-Spain border.