Case Study: Gotthard Base Tunnel

Gotthard Base Tunnel overview – for additional information see video link. Images obtained from SBB.ch, Herrenknecht.com, Lombardi.ch, TunnelTalk.com. 

The Gotthard Base Tunnel, constructed from 1999 to 2010 and open to traffic in 2016, is one of the most ambitious tunneling projects in the world. The 35.5-mile tunnel passes deep under the Swiss Alps, with over 6,500 feet of overburden in some areas. In addition to the high stresses from tunneling at such great depths, additional concerns such as geothermal gradient become relevant – in some places, the rocks along the GBT were well over 100 degrees F.

In order to accelerate the excavation process, the GBT was drilled from both ends using a combination of hard rock TBM and drill and blast technology. Accomplishing this required the use of state-of-the-art technology including strategically placed surface GPS stations and emergency shafts and tunnel ventilation and communication systems. However, a common theme in tunneling projects, no project is without issue – nine workers lost their lives during construction of the GBT.