Loetschberg base tunnel


Yet In the sixties, the idea to build a base tunnel through the Loetschberg came up. On this time, they were feared, that a new tunnel on the Loetschberg would be a too big competition against the Gotthard base tunnel. In 1971, a commission recommended to build the base tunnel at the Gotthard, and expand the existing Loetschberg line to two tracks. For a long time, there were not made any further plans. Until the project «Bahn200» started.

Because the Rawil tunnel between Lenk and Sion was not built, the wish came up to build the Loetschberg base tunnel including a car transport service instead. Also in view of the increase of 40-ton trucks the Loetschberg base tunnel gets more interesting. Finally in 1991 the parliament approved the construction of the base tunnels through the Loetschberg and through the Gotthard. On September 27 1992 the project came on voting and was accepted clearly by the people of Switzerland. After the government approved the first loan, the planning for the tunnels could start. So, in 1993 the BLS Alptransit AG was founded.

Variants
As with the summit tunnel there were worked out different variants for the new base tunnel. Although the federal government was given a variant, the cantons were able to enter additional options. After checking all the variants and not buildable lines were discarded, there were finally nine variants which should be reviewed in detail. 1993 the comparison of all variants was completed. In early 1995 the preliminary project finally approved.

Downsizing
Shortly after government approved, they wanted to reduce the costs of the NEAT-Project. The construction of the Loetschberg base tunnel should be moved or reduced to a single track tunnel. There was the fear, the tunnel would never been build, if it was moved onto a later date. So, BLS Alptransit worked out a reduced variant. The new project based on a single track tunnel, prepared for the full excavation. With some adjustments, this project approved by government and construction began.

Start of construction
In contrast to the summit tunnel, the base tunnel should be built not only from two sides. Two additional access galleries in Mitholz and Goppenstein (Ferden) were built. With those access points, the construction time could been reduced massively. The construction of the access gallery Ferden in Goppenstein started in June 1996. On September 18 2000 the level of the future base tunnel was achieved. After awarding the construction lot, the excavation for the base tunnel started on Mai 1 2001.

Construction site Goppenstein


As for the summit tunnel, a massive construction site was created in Goppenstein. (Nr. 1 on the map) From Goppenstein, a 4.1 km long tunnel leads to the level of the base tunnel. Due to the limited space in Goppenstein, a lot of machinery and facilities were created at the foot of the access tunnel. Excavated material and concrete aggregates were transported from and into the tunnel with conveyor belts. The transport from and to Goppenstein was mostly by train. There was a loading bay with two tracks near the railway station. A part of the excavated material was deposited in the vicinity. (Nr. 2 on the map)

For the workers there were barracks and a canteen in Goppenstein. But, in contrast of the construction site for the summit tunnel, the number of buildings and workers was significantly smaller. On their free time, the workers could pass the time in the nearby locations. The buildings in Goppenstein were completely demolished and the place renatured. Only an access road and the entrance to the tunnel are still there.

Tunneling
For break out the material, there were two different methods used in the base tunnel. From Steg and Niedergesteln there were two huge tunnel drilling machines with a diameter of 9.43 m in service. The rest of the tunnel was excavated by drilling and blasting. The tunnel from Wengi to Frutigen was built in open-cast mining. The excavated material was brought to two material management centers in Raron and Mitholz. A large part of the material was processed and used for making concrete for the interior construction.

In future, the trains should pass the tunnel with a speed of about 250 km/h. To make that possible, the rough surface had to be filled with concrete until there was a regular profile. To make the tunnel safe for the enormous pressure of the mountain, the concrete lining had to be at least 25 centimeters thick. In addition, the tunnel had to be protected against entering water. For leading the water out of the tunnel, a drainage system was installed. In some places there is much more water came out of the rock. To protect the concrete, an additional sealing foil was cemented.

The breakthroughs
As the tunnel was not excavated only from two sides, there was not only one breakthrough. The first one was on December 13 2002 in the west tunnel between Ferden and Steg. The last and most important breakthrough was on April 28 2005 between Mitholz and Ferden. There was a big celebration for this breakthrough.

Completion and commissioning
For safety reasons a slab track was installed in the tunnel. The railway sleepers are directly embedded in concrete and so, the attached rails could not move. On the parts with two separate tubes, crossovers were created every 300 meters. So in emergency, passengers can escape into the other tube, where they can be evacuated. To go off the train, there is a banquet. Embedded in these banquets, there are many supply and power lines. In addition to the track and overhead line equipment, there was lot of equipment for the signal boxes to install in the tunnel. Those parts were installed outwards in containers which were brought in the control centres.

At the end of the access road from Goppenstein, the emergency station Ferden was built. A train with problems can stop at this well-equipped railway station. There are some special crossovers which are very well ventilated. So smoke could not spread out. Even before the tunnel was completely equipped, the first test rides were done. In May 2007 the tunnel was finished and the first test rides through the whole tunnel were possible. After completion of the testing, scheduled train operations started in December 2007.