35-Mile-Long Tunnel in Alps to be World's Longest

Crews are blasting through the Alps as they work to build what will be the world’s longest tunnel, the Gotthard Base Tunnel between Zurich, Switzerland, and Milan, Italy. The 35-mile tunnel will host trains running through the Alps. “For such a huge project, you have to construct from different sites, because if you start at one portal and then on the other end, you need 20 or more years for the construction of the entire system,” said Heinz Ehrbar, chief construction officer with contractor AlpTransit.