Gotthard base tunnel
A byword for innovative railway engineering
The Gotthard base tunnel essentially consists of two 57 km single-track tubes connected by crosscuts every 325 m and with 2 multifunction stations at Sedrun and Faido. The trackbed of the NEAT Gotthard route has large curve radii (at least 3200 m as opposed to approx. 300 m on the current mountain route) and gentle gradients (max. 12.5‰ compared to 27‰ on the present route).
The two base tunnels at Gotthard and Ceneri are the core elements of the NEAT Gotthard route. To the north and south, the base tunnels connect with the existing SBB network via several kilometers of overground line that includes passing loops. The only immediate main line connection at a tunnel portal is at the southern end of the Ceneri base tunnel.
Gotthard base tunnel track
A ballastless low vibration track (LVT) system has been installed in the Gotthard base tunnel. Prefabricated concrete sleepers (W14 rail fastening system with Zw700 elastic rail pad) embedded on top of resilient pads in rubber boots were used to support the rails. Once the fastened track had been precision aligned, the sleepers were set in concrete. Instead of individual blocks, continuous concrete sleepers were used for the switches.
The installation method developed by the contractor delivered high laydown rates (more than 100 m "gross" of completed LVT per day), while at the same time satisfying the client's exacting quality requirements (e.g. positional accuracy: mean deviation of ±0.5 mm with a standard deviation of ≤1.0 mm). The excellent track positioning was confirmed by the results of high speed trials at velocities of up to 275 km/h conducted in November/December 2015.
Hydraulic switch systems
Hydraulic switch systems (VAE Hydrostar) new to Switzerland are being used in the Gotthard base tunnel. The main components are placed between the rails rather than beside the track, so avoiding costly ad-justments to the lateral conduit blocks in the tunnel. Using these switches along the entire NEAT Gotthard route simplifies maintenance and spare parts management.
When the contract documents for the railway engineering works were signed in 2008, the general consensus was that the Gotthard base tunnel would be opening in December 2017. Thanks to the impressive progress made on the remainder of the tunnel drive and various measures to expedite rail engineering operations, it was possible to bring forward the scheduled completion of the Capricorn project by one year. This called for extensive coordination and liaison, which also impacted the overground lines as well as the connections to the existing line.
Gruner Ltd was involved in the railway engineering works as part of its GBT and CBT track, installation and maintenance support mandate. During the shell construction phase, the company provided project and site supervision services within the Gotthard Base Tunnel North engineering consortium as well as environmental consultancy expertise.
Read more about the Gotthard Base Tunnel.