World's longest tunnel under Swiss Alps

August 25, 2015 17:08 IST 7 of 8
Workers in the Gotthard Base Tunnel install steel to stabilize the tunnel walls, in Sedrun, Switzerland, July 26, 2007. Crossing the Alps, the world's longest train tunnel should become operational at the end of 2016, consisting of two parallel single track tunnels, each of a length of 57 km (35 miles). Credit: Reuters