The construction: The railway tunnel
Tunnelling
Some 20% of the Lötschberg base tunnel was excavated by tunnel boring machines and the remaining 80% by means of conventional blasting techniques. In Raron (eastern tube) and Steg, two tunnel boring machines were employed. Blasting was used in the other zones due to varying geological conditions or structurally difficult rock varieties.
Material management
About 16 million tonnes of excavated material was accumulated in the construction of the Lötschberg base tunnel, an amount that would require 32,000 freight cars and a train 4100km long. Some 40% of the excavated material was able to be recycled, as a result of which the majority of the additives in the concrete used in the interior of the tunnels came from this recycled material. The materials were procured and prepared in Mitholz and Raron.
Track
The Lötschberg base tunnel is equipped with non-ballasted track, with the sleepers resting on shock-absorbing rubber footings, rather than directly on the concrete base. The advantages of a ballast-free track are that it has a longer lifespan, costs less to maintain, entails less danger of derailment and is more comfortable for passengers.
Overhead traction system
The trains draw their traction current from the overhead traction system. It is important that the current collection quality at the interface between the train and the power cable is high. The overhead traction system in the Lötschberg base tunnel is designed to allow a maximum speed of 250km/h and has power switching at intervals of approx. six kilometres. It needs to be able to conduct 2000 amperes of power into each of the two tubes. This high-current load-carrying capacity is necessary in order to provide sufficient power for six locomotives and for freight trains up to 1.5km in length.
Clearance gauge
The clearance gauge is the diameter required for the train to pass in a tunnel. The Lötschberg base tunnel is designed to allow sufficient clearance for the “Lötschberg Shuttle”, which has a contact wire height of 5.85m. This means that all trains operating in Europe can make use of the tunnel, which is not the case with the Gotthard route.
