(Image: Christian Hartmann/AP/Press Association Images) On
Friday, the gigantic drilling machine Sissi broke through the
last 1.5 metres of rock to complete the Gotthard Base rail
tunnel in Switzerland, the world's longest at 57 kilometres.
Eight 3000 ton drilling machines, each 400 metres long and
fitted with 60 drill heads, worked simultaneously for 8 years to
complete the pair of parallel tunnels 40 metres apart and 10
metres in diameter, connected every 320 metres by a cross
passage. In total, 153.5 kilometres of tunnel was drilled and 24
million tons of rubble removed by a team of 2600 workers. The
machines advanced at a rate of 20 to 25 metres per day, though
in areas where the rock was brittle, miners used explosives,
advancing 6 to 10 metres per day. Eight workers died during
construction. The €9.1 billion tunnel connects Erstfeld, a
municipality in the Swiss canton of Uri, with Bodio in the Swiss
canton of Ticino. The New Transalpine Rail Link, also known by
its German acronym, NEAT, will ease pressu