Passes and Tunnels

Most Alpine passes higher than 6,000 feet (1,800 m) above sea level are blocked by ice and snow in winter. Rail and highway tunnels have been built under the principal passes, allowing continuous traffic the year round. An exception is the Brenner Pass, which at 4,508 feet (1,374 m) is low enough to be kept open all year.

Alpine tunnels were limited to rail traffic until 1964, when the Great St. Bernard auto tunnel was opened. The St. Gotthard Tunnel, opened in 1980, is the world's longest road tunnel; the Simplon, consisting of tubes opened in 1905 and 1922, is one of the world's longest rail tunnels.