Lötschberg Base Tunnel

thumb|upright=1.44|right|The north portal in [[Frutigen]]

thumb|upright=1.44|right|South portal near [[Raron]]

The Lötschberg Base Tunnel (LBT) is a railway base tunnel on the BLS AG's Lötschberg line cutting through the Bernese Alps of Switzerland some below the older Lötschberg Tunnel. It runs between Frutigen, Bern, and Raron, Valais.

The Lötschberg Base Tunnel was built as one of two centrepieces of the New Railway Link through the Alps. Construction of the LBT began in 1999 and achieved breakthrough during 2005. It was completed in June 2007 and the first train operations began in December 2007. This initial project was estimated to cost SFr4.3 billion ($3.59 billion).

The LBT was saturated within a few years of opening due to a single-track section. Without a second bore, its overall capacity is greatly reduced. During 2016, a planning contract was awarded for the completion of the second track of the LBT, which has been estimated to cost 1 billion Swiss francs. The resulting plan was presented in spring 2019. In early 2024, Parliament decided to complete the second bore, with an estimated cost of SFr 1.7 billion.

Construction

Initial construction

The LBT was principally constructed to ease lorry traffic on the Swiss road network by providing faster routes for rail-based freight as an alternative. Reportedly, between the 1980s and 2000s, traffic on the north-south European axis (North Sea Ports to/from Northern Italy and along the Blue Banana) had increased more than tenfold, necessitating infrastructure investments to better cope with rising demands.

In 1994, early drilling was conducted in the area. It was largely excavated using a combination of traditional techniques, including drilling and blasting. Roughly 80% of the tunnel was built using these conventional practices. The excavation process reportedly used of explosives, while the material extracted would have filled a freight train that was in length – one-tenth of the Earth's circumference. The LBT overran its budget of roughly $2.7 billion by around $840 million, which has impacted its operation. Initially, only regular freight services traversed the LBT, along with a minority of international and InterCity passenger trains (without stops between Spiez and Brig); passenger trains continued to operate on the old timetable (the travel time between Spiez and Brig was considered to be 56 minutes until December 2007, even if actual travel time through the LBT was only about 30 minutes). Since February 2008, the LBT has been routinely used for normal InterCity routes. Travel time between Visp and Spiez is about 28 minutes, of which 16 minutes is spent inside the LBT.

Additional phases

As a consequence of spiraling costs attributable to the overall NRLA project, it was decided to redirect funds from the Lötschberg tunnel to the Gotthard Base Tunnel. This funding decision leaves the LBT in a partially-completed state for a protracted period. Once fully complete, the LBT will consist of two single track bores side by side from portal to portal, connected about every with cross cuts, enabling the other tunnel to be used for escape.

The construction process was divided into three phases, of which only phase one has been completed to date:

Phase one: construction of about 75% of the length of the western tube and the complete east tube of the main tunnel, the Engstlige tunnel, the two bridges across the Rhône, and the branch bore from Steg. Tracks are laid in the eastern tubes of the LBT and Engstlige tunnels, and for some in the western tube of LBT, starting from the south.
Phase two: laying of tracks in the bored but not equipped part of the western tube of LBT, and in the western tube of Engstlige tunnel.
Phase three: construction of the remaining of the western tube, laying tracks on the Steg branch, and connection of this branch to the Brig-Lausanne main line towards Lausanne.

Currently, from south to north, 40% of the tunnel is therefore double track, 40% is single track with the second bore in place but not equipped, and 20% is only a single track tunnel with the parallel exploration adit providing the emergency egress. This unused western bore has been used by maintenance crews as a means of accessing the active eastern tunnel; an adjacent exploratory bore driven during the early 1990s has also proved useful for such purposes. The resulting plan was presented for review in early 2019, and a decision between funding only phase two or both phase two and three was initially expected in 2023. The first option would naturally have been cheaper and would have taken two years less to build, but it would have provided a much lower capacity and would have required an eight-month full closure of the line.

The of single track without any passing loop greatly complicates operations. Typically, trains using the LBT are scheduled together in batches that run in one direction, separated by intervals which must be longer than the last train in a batch needs to cross the single-track section; trains more than seven minutes late are either routed via the old line or must wait for the next available timetable slot in their direction in the LBT, incurring long further delays in either case. In addition to cleaning the tunnel interior, removing the sand and excess water via suction, and the flushing out of its drainage system, temporary steel tanks have been installed in the bore with regular inspections of the tunnel with a particular focus on this issue. Furthermore, solutions to prevent reoccurrence in the long term have been identified and are to be compiled into a plan for approval by the Federal Office for Transport during late 2020; if approved, sections of the LBT shall be modified accordingly.

Travel speeds

Regular freight trains:
Qualified freight trains:
Passenger trains:
Tilting passenger trains:

Geothermal energy

Warm groundwater continuously drains from the LBT. The warmth of this water flowing out of the tunnel is used to heat the Tropenhaus Frutigen, a tropical greenhouse producing exotic fruit, sturgeon meat and caviar.

References

External links

Official project site
Official site of the "ARGE Bahntechnik Lötschberg" the general contractor for the railway technology
AlpTransit Portal of the Swiss Federal Archives
Site with a movie documentation about the engineering and the works (railway technology)
Rail Technology in the Lötschberg Base Tunnel
Image Gallery on a contractors site