Mont Cenis tunnel authorizedIn 1857, a bill was passed by the Italian parliament authorizing the boring of the Mont Cenis Tunnel 8 miles through the Alps between Modane and Bardonnêche. Two weeks later, the first blast was fired on the Italian side by King Victor Emmanuel. During 1858 with only hand drilling methods only 1,506 feet was excavated, total, from both ends. However, in 1861, French engineer Germain Sommeiller introduced pneumatic drills capable of 200 strokes per minute which increased progress by 3½ times to 5,364 -ft in 1870. A wheeled carriage on rails carried up to nine air-driven perforators that drilled a pattern of holes for blasting the rock face. Compressor plants at each end were water powered. When opened on 17 Sep 1871, this triumph of engineering was the world's first important mountain tunnel.*«[Image top: Mont Cenis Tunnel entrance arch; bottom: Sommeiller Boring Machines.] |
