Lötschberg Base Tunnel (Lot Mitholz)

The first base tunnel for rail transport in the Alpine arc

To ease traffic congestion, Switzerland decided in the 1990s to construct two transalpine railway links, the Gotthard Base Tunnel and the Lötschberg Base Tunnel. The Mitholz section of the 32,5-kilometre long Lötschberg Base Tunnel extends from the northern portal in Frutigen over a distance of 17 kilometres to the cantonal border.

Under STRABAG's leadership, the consortium entered new technical and logistical grounds. For the first time in tunnels of this length with single-track tubes, the flexibility of wheel operation was used instead of conventional track operations. A total of 3.500 tones of liquid two-components explosive provided virtually unlimited storage possibilities. The use of conveyor belts in drill-and-blast tunnelling proved to be a highly successful innovation. Consequently, the excavated material had to be crushed to a suitable grain size directly in the tunnel face area using mobile crushing plants.

To accommodate all necessary installations, including power supply, ventilation, blast-fume extraction and cooling, so-called trailing suspension platforms were used in all three tunnel drives. These platforms were mounted on rails suspended from the tunnel roof at a height of three metres and advanced together with the excavation works.

As planned from the outset of the initial exploratory investigations, the tunnel went into operation on schedule with the timetable change in 2007.

Scope of Work

• Construction of an approximately 17 km section of the Lötschberg Base Tunnel 
• Use of an innovative rubber-tired transport system in the single-track tunnel tubes 
• Application of two-component explosives during tunnelling operations 
• Removal of excavated material via conveyor belts 
• Crushing of excavated rock using crushing plants 
• Deployment of mobile suspended platform systems