{"id":23236,"date":"2017-11-06T16:47:26","date_gmt":"2017-11-06T15:47:26","guid":{"rendered":"https:\/\/www.ferrovial.com\/blog\/en\/?p=23236"},"modified":"2025-12-12T00:23:50","modified_gmt":"2025-12-11T23:23:50","slug":"megatunnels-ii-earth-is-neither-created-nor-destroyed","status":"publish","type":"post","link":"https:\/\/www.ferrovial.com\/blog\/en\/2017\/11\/megatunnels-ii-earth-is-neither-created-nor-destroyed\/","title":{"rendered":"Megatunnels II: earth is neither created nor destroyed"},"content":{"rendered":"

In the 2nd<\/sup> century AD and driven by his insatiable thirst for mining, Roman emperor Trajan gave orders for the course of the river Sil in the northeast of Iberia to be diverted. This was done by excavating a 120-metre tunnel between the provinces of Lugo and Ourense, an area which has come to be known as Monte Furado<\/em> (the hill with a hole).<\/p>\n

Not far from that very spot, work on the 8.1 km Espi\u00f1o tunnel<\/a> \u2013 part of the high-speed rail link between Madrid and Galicia and a fine example of innovation on various counts \u2013 is nearing completion. Between the two lie almost 2000 years of fascination in the search for overcoming nature\u2019s obstacles<\/strong>, a history full of spectacular infrastructures which the world now calls megatunnels.
\nConstruction of the Espi\u00f1o tunnel for the Madrid-Galicia high-speed rail link.<\/p>\n

\"Espi\u00f1o<\/a>

Construction of the Espi\u00f1o tunnel for the Madrid-Galicia high-speed rail link<\/p><\/div>\n

But what is a megatunnel?<\/h2>\n

It\u2019s not a word that appears in the Oxford English Dictionary, or in engineering manuals. \u201cThe prefix mega, in addition to being a unit of measure, is obviously very much linked to the media, due to the idea of grandeur it conveys to the listener or reader,\u201d explains Juan Carlos Guerra Torralbo, a civil engineer<\/strong> and head of geotechnical projects at Ferrovial-Agroman.<\/p>\n

Yet this engineer, having seen so much in so many tunnels in his more than 25 years of experience, has his own definition. \u201cI think a megatunnel could be defined as an underground construction made artificially by man to allow the passage of vehicles, people, goods and services, and which, given its special characteristics, can be classified as an extraordinary piece of building work.\u201d<\/p>\n

Thus, a megatunnel would be something out of the ordinary, a deviation from the norm, and, as such, something that captures our attention<\/strong>. So here are some of the largest tunnels running beneath the surface of the Earth, leaving Monte Furado as little more than a hole in the hill.<\/p>\n

Kilometres below the ground (and the sea)<\/h2>\n

Almost 54 km long, the Seikan tunnel<\/strong>, linking the Japanese islands of Honsh\u00fb and Hokkaid\u00f4, was for years the world\u2019s longest tunnel. Built in 1988, the tunnel runs 100 metres below the seabed, and 240 metres below sea level.<\/p>\n

\"Seikan<\/a>

One of the entrances to the 54 km Seikan tunnel \/ Wikimedia Commons<\/p><\/div>\n

\u201cToday, the honour of being the world\u2019s longest tunnel is held by the Gotthard Base Tunnel, in Switzerland<\/strong>, which runs for 57 km at a depth of 2km under the Alps, linking Zurich and Milan in under 3 hours,\u201d says Guerra Torralbo.<\/p>\n

Europe also has its own massive projects, such as Eurotunnel<\/strong>, built in 1994 under the English Channel and running for just over 50 km. Or the Marmaray tunnel<\/strong> in Istanbul, the deepest in the world, which crosses the Bosphorus Strait at a depth of 1,800 metres to connect Asia and Europe.<\/p>\n