Construction lot H21 Sill Gorge: all tunnelling works completed

Another important stage in the H21 Sillschlucht construction lot was reached at the end of November 2023. After a construction period of around 15 months, the last concrete works for the wall and ceiling elements of the “ Silltal” tunnel were recently finished. This means that all tunnels in this construction lot have been completed.


A brief reminder: The Silltal tunnel is a feeder tunnel to the actual Brenner Base Tunnel and part of the access route that connects Innsbruck main station with the north portal (Viller Berg portal).


The entire length of the tunnel is designed as a watertight structure (“white tank system”), which is  equipped with additional bituminous seals for walls and ceilings due to the required long service life.


The tunnel was constructed using the cut-and-cover method. To this end, the existing slope in the Sill gorge first had to be removed and secured with five anchor beams and 133 prestressed anchors due to its difficult geology. At the same time, excavation work was carried out, during which approx. 67,000 m³ of material was produced. Most of this spoil will later be used for backfilling to restore the original contour of the site. This work began in November 2023 and is expected to be completed in September 2024.


Approx. 13,720 m³ of concrete (including bored piles and excluding the anchors) was used for the concreting work on the tunnel. Approx. 2,000 tonnes of steel were required as reinforcement.



Facts about the Silltal tunnel:


  • Neighbouring structures: railway overpasses over the Sill in the south, retaining wall along the Sill in the north
  • Designed as a single-tube tunnel in the north and a twin-tube tunnel further south
  • Length approx. 133 m (west track), height (track to ceiling) 6.8 m
  • Volume of soil excavated: 67.000 m³
  • Amount of concrete used: 13.720 m³