Loire. Saint-Étienne/Lyon SNCF line: a project to reinforce a weakened embankment

The bad weather of October 17, 2024, is still making headlines… Last fall, the incessant rain caused extensive damage in the Gier Valley and the Pilat Mountains. But since then, other problems have been uncovered. This is the case near Tartaras, where the railway line between Saint-Etienne and Lyon has been disrupted due to a new landslide.

"This line is the busiest in France, excluding traffic in the Paris region. It's therefore only right to carry out the work as quickly as possible and in the best possible manner," explains Didier Llorens, operations manager for SNCF Réseau. And the least we can say is that the project is significant.

With an estimated cost of nearly 5 million euros (including studies) and fully covered by SNCF Réseau, these improvements had been planned for a long time but were scheduled for 2027. "Faced with the reality of the danger that the situation could present, we decided to undertake the rehabilitation earlier," he continues.

After a long and meticulous effort to preserve the flora and fauna, the workers took possession of the site nearly a week ago. "We established the base camp on the Glattard Mill Road in the commune of Tartaras. This makes it easier to reach two sites located a short distance from each other to work on areas between the Cholet and France tunnels, in the communes of Trèves and Tartaras."

The intervention was made necessary due to the proximity to the railway line, a distance estimated at nearly 5 meters. "Train speed has been reduced to nearly 40 km/hour on this section. This allows us to work during the day without interrupting the line's traffic," adds the manager, specifying that "it is however not without consequences for the train schedule." A concrete rock wall will be built over 100 linear meters as well as a facing with shotcrete to prevent the river from eroding the structure. At the base of the construction, a continuous footing, under the bed of the Gier, will provide greater stability to the building.

In the second zone, 200 meters downstream, plant engineering will be used to stabilize the banks. "Specific types of plants will be installed to restore the watercourse's full capacity," explains Didier Llorens, adding: "Rock groynes will also be created to slow the water's speed and send it back to the other side."

Improvements will be made to preserve the flora and fauna, particularly by creating shelters for birds such as the kingfisher. Taking great precautions, the project manager announced that the work should be completed "towards the end of September" to avoid the period associated with the risk of further flooding.