The world's longest and deepest rail tunnel has officially opened in Switzerland, after almost two decades of construction work. The 57km (35-mile) twin-bore Gotthard base tunnel will provide a high-speed rail link under the Swiss Alps between northern and southern Europe.
The tunnel has overtaken Japan's 53.9km Seikan rail tunnel as the longest in the world and pushed the 50.5km Channel Tunnel linking the UK and France into third place.
When my wife and I visited Switzerland in the Fall of 2012, I remember reading brochures about this tunnel. One of the issues is whether or not it was close enough to big dams and the rock was porous enough that water would leak out of the dam's reservoir into the tunnel. There was also concern of lowering the water table under the dam and changing the strength of the rock around the dam enough to cause the dam to break. Evidently these problems did not happen.