Lötschberg Base Tunnel, Lot Mitholz

In the 1990s, Switzerland decided to build two transalpine rail links, the Gotthard Base Tunnel and the Lötschberg Base Tunnel, to relieve traffic congestion. The Lötschberg Base Tunnel, with a total length of 32.5 km, was the first base tunnel in the entire Alpine arc to be put into operation for rail traffic. The Mitholz construction lot extended from the north portal in Frutigen over 17 km to the cantonal border, thus covering half of the entire tunnel length.
 
The consortium, led by STRABAG, broke new technical and logistical ground in a number of key areas. This was the first time that the flexibility of wheel operation was used on such long tunnels in single-track tubes instead of the usual track operation. Furthermore, binary liquid explosives were used for the blasting, offering almost unlimited storage possibilities (a total of 3,500 tonnes were used). A very successful innovation was the use of conveyor belts in blasting drives. This meant that the excavated material in the face area had to be crushed to a suitable grain size using mobile crushing plants. In order to be able to accommodate all the necessary installations, such as power supply, ventilation, blasting vapor extraction and cooling on a mobile basis, “trailing suspension platforms” were used in all three drives, which followed the drive on rails suspended from the roof at a height of approx. 3 m.
 
As planned at the beginning of the first exploratory measures in 1994, the tunnel went into operation on schedule for the 2007 rail timetables.