Unusually, Switzerland’s latest batch of tunnels are not being built deep under mountains but run just below the surface of the relatively flat Emmethal in the north central area. They are part of the country’s Rail 2000 project, SBB’s (Swiss Railway’s) contribution to Second Railway Age projects throughout Europe for fast trains, and its first railway construction for 100 years. The new line will carry 200km/h trains from Geneva to Basel and then Zurich, using mostly upgraded existing track but with a key 45km long new-build stretch through the Emme valley. Primarily Swiss contractors are building 11 projects ranging from 400m to 3160m. Construction methods vary from excavation within battered slope trenches to use of diaphragm walls for the 1580m long crossing of the Emme river and secant pile support for concreting work in some hillsides. Tunnels are mostly for twin track line enclosed in a waterproofed concrete arch with a 7.5m internal height and 11.3m width. The new line is due to open in 2005.
