Gotthard Base Tunnel: Bauer expertise for the longest and deepest railway tunnel in the world

Switzerland is becoming smaller: On June 1, the Gotthard Base Tunnel was ceremonially opened in the presence of state guests from across Europe. Over 1,100 guests and 300 media representatives took part in the official maiden journey through the tunnel, which is 57 kilometers long and runs up to 2,300 meters below the Alps. It is the longest and deepest railway tunnel in the world. The Swiss subsidiary of BAUER Spezialtiefbau GmbH and BAUER Umwelt GmbH were also involved in the construction project of the century.

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The twin-tube Gotthard Base Tunnel ran from Erstfeld to Bodio. Construction work started in 1999: the tunnel was excavated from five different starting points simultaneously. The northernmost starting point was in Erstfeld, from this point the tunnel was extended towards the south. In 2005, BAUER Spezialtiefbau Schweiz AG carried out the specialist foundation engineering works here for the ARGE VGE Lot 1. The main works consisted of bored piles with diameters of 1,200 and 1,500 millimeters, which were drilled to 33.5 meters under extremely difficult conditions, i.e. in boulder-like landslide material. A BAUER BG 40 rotary drilling rig was used for this. BAUER Spezialtiefbau Schweiz AG installed permanent anchors up to 70 meters long in the pile wall. For this, bore holes were drilled through the boulder-like unconsolidated rock through to the solid rock. As a first step, the excavation pit served as a starting pit for the tunnel boring machine. After completion of the drilling works, the tunnel was constructed in this area using the open-cut tunnelling method, then the excavation pit was refilled.

From January 2011 to August 2013, BAUER Spezialtiefbau Schweiz AG also constructed foundation piles for a 1,060 meter long viaduct between Lugano and Bellinzona. For the static basis of the structural design, test piles were constructed beforehand and static pile load tests were carried out. A total of 313 cast-in-place concrete piles with a diameter of 1,200 millimeters and lengths of up to 29 meters were drilled and concreted.

BAUER Umwelt GmbH was also involved in the construction of the tunnel. The company was commissioned – partly as a joint venture – with the construction and operation of two water treatment plants: in Amsteg, Switzerland, where the resulting mountain water had to be treated before its introduction into the river, and in Faido, where Bauer installed a nitrite treatment plant due to the high nitrite concentration resulting from the explosives used in the tunnel driving.

The breakthrough in the east tunnel took place on October 15, 2010; the west tunnel on March 23, 2011. Test operation began in October 2015. At the start of June, AlpTransit Gotthard AG handed over the operation of the tunnel to Swiss Federal Railway (SBB). After further testing, the tunnel will be put into operation as the heart of the new Alp Transit on schedule on December 11, 2016. Traveling by train on the north-south line will soon be much more attractive for people as well as goods from the whole of Europe.