BLS will refurbish the Lötschberg Base Tunnel this year following water ingress
In order to avoid further ingress of water and sand in the Lötschberg Base Tunnel, BLS is seeking to refurbish the tunnel as quickly as possible. It is constructing a cavern in the affected area so that the water can flow out and the sand be deposited as sediment. During the four-month construction period from early September to mid-December, the tunnel will remain operational on one track.
In future, sand is to be prevented from entering the Lötschberg Base Tunnel in the runoff from the mountains. To ensure the long-term operational safety of the trains through the tunnel, BLS is refurbishing the affected area in the eastern bore for the dual-track section. The company is excavating a cavern to the side of the tunnel bore and installing a sedimentation tank with a 2,000-cubic-metre capacity. The mountain runoff flows into this sedimentation tank; any sand is then deposited as sediment and the purified mountain runoff diverted to the Raron portal. The sand deposits can be removed from the tunnel in rail wagons. Based on current plans, the cost of the refurbishment will be around 15 million Swiss francs. The project will be funded via the service agreement with the Swiss government.
The majority of trains use the Base Tunnel
BLS has submitted the construction plans to the Federal Office of Transport for approval. Construction is set to begin in April and be completed before Christmas. The eastern bore will be closed during the four-month construction period and trains diverted along the single track through the western bore. The majority of SBB passenger trains will run through the Base Tunnel. BLS is currently working on the detailed timetable with the affected passenger- and freight-transport companies.
Immediate measures have proved effective
In February and March, the eastern bore of the Lötschberg Base Tunnel had to be closed when unexpected water ingress washed sand into the tunnel. As an immediate measure, BLS installed steel sedimentation tanks in the affected area of the tunnel. At present, water is flowing continuously into these sedimentation tanks. A few cubic metres of sand are currently being deposited in the eastern bore, and the tanks are emptied once a week. The sedimentation tanks will remain in place until BLS has rendered the cavern operational. In the less heavily affected western bore, there has been no further water ingress since the second such incident on 13 March.