Lötschberg tunnel eaten away by sulfurous mountain water

Installed a few years ago as part of the tunnel renovation work, the new concrete lining of the Lötschberg peak tunnel is already being eaten away by sulfurous mountain water. The railway company BLS will probably renovate the track at the two damaged locations by the end of the year, it announced on Tuesday.

Observed last summer on the concrete track, the damage is located, on the one hand, approximately 3.5 kilometers from the northern entrance to the tunnel, near Kandersteg (BE), and on the other hand, approximately 4 kilometers from the southern entrance, near Goppenstein (VS). The high sulfate content in mountain water causes surface cracking and spalling of concrete. In certain places, the anchoring of the rails is weakened. The areas were stabilized to ensure safe train operations, before repairs began.

Concretely, the damaged track will be replaced by sulfate-resistant concrete, over a length of approximately 50 meters. Where the current concrete occasionally shows superficial cracks and bursts, over approximately 60 meters, the track will be repaired and impregnated. Finally, on approximately another 80 meters, where the roadway is wet due to sulfur water, the concrete will be cleaned and impregnated.

“According to the current state of knowledge, repairing the damage costs between two and three million francs. BLS assumes that the repair of this damage is largely assured,” the railway company said on Tuesday. The latter says it can carry out repairs without interrupting train operations. The work, which will last four to six weeks, will be carried out outside holiday periods.

The renovation of the Lötschberg tunnel has made headlines since work began in 2018. In addition to engineering problems, the construction site caused the death of thousands of trout due to the illegal disposal of contaminated ballast into the lake. . On the cost side, the work carried out in this 15-kilometer tunnel should have cost 105 million francs and be completed at the end of 2023. The project was then re-evaluated at 180 million francs.