<p>With the urban population increasing, conurbation is getting more and more crowed, traffic jam happens everywhere. In this case, utilization of the underground space has become an effective way to undertake this set of problems. Tunnel construction is one ...

<p>At the time when it is completed, the Gotthard Base Tunnel in Switzerland, with a total length of 57 km, will be the longest railway tunnel in the world. The complete tunnel system consists of 153.3 km of access tunnels, shafts, railway tunnels, connecting ...