The Culoz–Modane railway, also commonly referred to as the Maurienne line (Ligne de la Maurienne), is a major international railway line in southeastern France. It connects the town of Culoz in the Ain department to the border station of Modane in the Savoie department. The line serves as the French section of the international rail link between Lyon, France, and Turin, Italy, via the Fréjus Rail Tunnel.
History
The line was originally conceived by the Victor Emmanuel Railway company to connect the disparate parts of the Kingdom of Piedmont-Sardinia. Construction began in the 1850s, with the section between Culoz and Saint-Jean-de-Maurienne opening in 1856. Following the Treaty of Turin in 1860, which saw the annexation of Savoy by France, the railway came under French jurisdiction and was eventually integrated into the Chemins de fer de Paris à Lyon et à la Méditerranée (PLM) network. The final section to Modane, including the Fréjus Rail Tunnel (also known as the Mont Cenis Tunnel), was completed and opened for traffic in 1871.
Route and Technical Characteristics
The railway spans approximately 135 kilometers (84 miles). From Culoz, it runs southward toward Chambéry before turning east and following the valley of the Arc River through the Maurienne region.
The line is characterized by its significant alpine gradients, particularly on the section between Saint-Michel-de-Maurienne and Modane, where the tracks ascend toward the entrance of the Fréjus Tunnel. To manage the steep terrain, the line features numerous engineering structures, including extensive tunnels, viaducts, and reinforced embankments.
Electrification
The Culoz–Modane railway was a pioneer in heavy-load mountain electrification. Due to the difficulty of operating steam locomotives on steep inclines and within long tunnels, the PLM electrified the line between 1925 and 1930. It initially utilized a 1,500 V DC third-rail system, which was unique for a mainline of this scale in France. This system remained in operation until 1976, when it was replaced by standard 1,500 V DC overhead catenary to ensure compatibility with modern rolling stock.
Current Usage
The line remains a critical corridor for both passenger and freight transport within the Trans-European Transport Network (TEN-T). It facilitates high-speed passenger services (TGV and Frecciarossa) between Paris and Milan, as well as regional services (TER Auvergne-Rhône-Alpes). It is also a primary route for rail freight crossing the Alps.
As of the 21st century, the line's strategic importance is being supplemented by the construction of the Lyon–Turin high-speed railway, which includes a new base tunnel intended to bypass the steepest sections of the original 1871 route.