Road and railway tunnels shorten travel distances, speed up transportation and facilitate smoother traffic.
The intensity of tunnel building works began to rise in coherence with railway transport development in the 19th century; however, record-high numbers of tunnel construction projects are being reached at the present day. For instance, it is hard to imagine life in big city agglomerations without underground railways, where more and more newly-built structures are being moved under the surface. Various building methods are employed; some of them are older techniques going through certain improvements, while some others are newly created. Thanks to state-of-the-art technologies, today it is possible to construct tunnels even in poor geological conditions, under the water level of rivers and the sea and cover distances that were not imaginable in the past.
The world’s longest railway tunnel is the 57-kilometres-long Gotthard Tunnel in Switzerland.