Tunnel construction

Tunnels are constructed where they are needed.

In the case of a road tunnel, for example, the rock to be excavated through cannot be chosen; the tunnel has to pass through the rock formations that are «in the way».

During tunnel construction, unexpected rock conditions and water penetration often present considerable challenges for engineers and miners. For this reason, tunnel construction can not be planned down to the last detail even today, despite significant advances in preliminary investigation of the rock formations.

Tunnel boring machines are generally used in hard, compact rock.

Rocks that are soft and strongly water-bearing are more challenging for the tunnelling engineers and are generally excavated by drilling and blasting. The tunnels are secured continually as drilling advances and may be lined with shotcrete.


Small tunnel boring machines were used at the Grimsel Test Site. The tunnel diameter was 2.3 metres or 3.5 metres. Image: Comet Photoshopping, Dieter Enz

We use cookies to improve your experience on our website. By browsing this website, you consent to our use of cookies. For more information on our “Legal Conditions and Privacy Policy”, click here. Find out more about legal and data protection here
I accept