Photo: Courtesy of ALP Transit The first of two record-breaking tunnels on Switzerland’s twin-bore, 57-kilometer-long Gotthard Alpine rail crossing broke through on Oct. 15. The breakthrough finishes the east drive of the Gotthard twin tunnels, which are among several being built through the Alps. The west tunnel’s breakthrough is scheduled for next spring. The joint-venture Tunnel AlpTransit Ticino (TAT) made the breakthrough at the tunnel’s midpoint, connecting to the awaiting “Sedrun” stretch. The tunnel is expected to start rail operations in late 2017 at an estimated cost of $10.3 billion.
Arch dams, classically curved monoliths situated in narrow valleys, are not as common as other types of dams, such as embankment dams and gravity dams. ENR takes a look at some of the biggest arch dams in the world, both completed and under construction.