SNCF Réseau

Ligne Nouvelle du Sud-Ouest (LNSO) is a major railway programme focused on sustainable mobility and stronger connections across southwestern France. It brings together several infrastructure projects: new lines and stations between Bordeaux and Toulouse and between Bordeaux and Dax, a future line from Dax to Spain, and upgrades to existing railway infrastructure north of Toulouse and south of Bordeaux. The programme is being delivered in two phases. The first includes the Bordeaux–Toulouse and Bordeaux–Dax projects, along with the upgrades near Toulouse and Bordeaux; the second covers the new Dax–Spain line.

The LNSO is designed to complement, rather than replace, modernisation of existing tracks. Its aims include easing rail bottlenecks, supporting everyday and long-distance travel, and creating capacity for freight services. The Agence Ligne Nouvelle du Sud-Ouest, established in 2023, leads and coordinates the programme, while the Société du Grand Projet du Sud-Ouest contributes to its financing through funding from regional and local authorities. The organisation also shares project updates, documentation, studies and information about environmental aims, consultation and local integration.