Project track replacement in the Lötschberg summit tunnel completed
ARGE Marti LBST has been working in the Lötschberg summit tunnel since 2018, replacing the existing ballasted track with a slab track. The over-100-year-old, 14.6 km rail tunnel between Kandersteg and Goppenstein connects the cantons of Bern and Valais. It is the heart of Lötschberg mountain railway from Spiez to Brig. In August 2023, Marti installed the last meters of track, then set and cast the golden crosstie as the symbolic conclusion of the project.
The ballasted track from the 1970s in the Lötschberg summit tunnel had reached the end of its service life. ARGE Marti LBST was therefore commissioned to replace the old track with a new slab track. One particular challenge was that the track replacement had to be conducted during ongoing operations as full closure of the tunnel was not possible. To meet the challenge, logistical solutions and constructions were developed in the run-up to the project. In collaboration with Marti Technik, the team from Marti Tunnel Ltd. developed an innovative transport system.
Custom-built solutions for an optimal construction process
To transport material in the construction phase, the tunneling crew installed a specially designed transport track with a monorail on the tunnel vault. Movable crane attachments on the monorail were then used to remove the old track panels and lay the new ones. Ballast and concrete were transported between the construction section and the work train via a mobile conveyor belt system suspended from the monorail.There were also five different train types used, all specially designed by Marti for this project: The drilling car was used to drill the anchors for the monorail on the tunnel vault. The track-laying train was used to remove the old track sections and install new ones. A ballast train transported the excavated ballast from the tunnel and the concreting train delivered fresh concrete to the tunnel for the new slab track. And finally, the supply train with emergency containers, toilets, stored materials, water treatment system and supply. The trains were driven by three of the company’s own locomotives.
A deceptively tricky project – by no means just «removing a bit of track ballast and then installing some concrete.»
Intensive construction phases and tight spaces
BLS required the use of both tracks during the winter months, so the intensive construction phases for Marti were between Easter and December. The construction crews used the intervening period for maintenance and preparatory work. During the entire construction period, the tunneling crews were confronted with extremely tight and dangerous working conditions, with continuous rail traffic on the adjacent track. The safety of the crews was therefore the utmost priority. Crews worked in three shifts, from Monday morning to Saturday morning. An in-depth look at the different stages and processes is presented in the project film Lötschberg summit tunnel – Installation of the slab track during operations.
Summer 2023 – the final meters of track are in place
On the night from the 15th to the 16th of August, Marti laid and cast the last tracks. The milestone was symbolically celebrated with the casting of the final golden crosstie, and ultimately celebrated by those involved with a project-completion party at the installation site in Kandersteg. The team would later clear the tunnel and the installation site and hand the tunnel back over to BLS.