Drilling machine, with four steel tipped drills used in cutting the Arlberg Tunnel, Austria. Before the advent of tunnel boring machines, drilling and blasting was the only economical way of excavating long tunnels through hard rock, where digging is not possible. Drilling jumbos are usually used in underground mining, if mining is done by drilling and blasting. Historical jumbos were powered by compressed air. The Arlberg Railway Tunnel (Arlbergtunnel), with a length of 6.6 miles, is the central part of the Arlberg railway in western Austria between the provinces of Tyrol and Vorarlberg. The tunnel runs through the Arlberg massif at the northeastern end of the Rhaetian Alps. It opened on December 21, 1884 as a single-track tunnel. The traffic through the tunnel grew so quickly, that a second track was opened by July 15, 1885.