Engineering Wonders of the World
Volume III

162 ENGINEERING WONDERS OF THE WORLD. vated.* The highest point above sea-level in the Simplon Tunnel is 2,313 feet, as compared with the 4,299 feet of the Arlberg, the 3,786 feet of the St. Gothard, and the 4,245 feet of the Mont Cenis tunnel. Thanks to this very moderate elevation, and to the absence of severe curves on the approaches, the run through the Alps is made at so good a speed that Milan has been brought within 25| hours of London. In connection with the new Simplon route another great project, the Loetschberg, is in hand. From Brieg a line will run parallel to the old railway to Lausanne The Loetsch= for m|]es then turn north- berg Tunnel. wards, plunge under the Loetschberg through an 8|-mile tunnel, and find its way down the Kander Valley to Frutigen, which already has railway com- munication through Thun and Berne with Germany and Northern France. It will there- fore be a rival to both the Lausanne and the St. Gothard routes. The tunnel, which, has a maximum height above sea-level of 4,084 feet, was begun in October 1906, and, to fulfil the contract, must be completed by September 1911. It will accommodate two tracks. The approaches will include some very stiff gradients, espe- cially on the Frutigen side, where there is a. 9|-mile stretch of 2’7 per cent., and to obtain this much tunnelling and looping is required. The alternative of a longer, lower * Proceedings of the Institute of Civil Engineers, vol. clxviii. level tunnel was given due consideration, but abandoned on account of the decision to use electric haulage, which is more economical than steam on steep grades. It is anticipated that the extra power needed will not cost as much as the interest on the extra capital re- quired for a low-level tunnel. Before closing this article we must refer to the tunnel through the High Tauern Alps, in the Austrian Tyrol. The completion of this tunnel in January 1909, and of the railway between Bad ^auern ~ ~ . Tunnel. Gastein and Spittal on tne Drave, has opened a route of international importance between Munich and Trieste, vid Salzburg, Gastein, and Villach, and has short- ened the journey from Salzburg to Trieste by 154 miles. The whole of the new track is remarkable for its engineering features, which include many viaducts and a number of tun- nels, among which the Tauern is the most notable. This has a length of 5| miles, and was driven through a mountain composed of felspar, gneiss, quartz, and detonating shale. The last gets its name from its breaking off at the face with loud explosions when exposed to air. The hardness of some of the rocks, inroads of water, and the peculiar behaviour of the shale caused much trouble and delay ; but all difficulties were overcome by the perseverance characteristic of the engineer, and the galleries met on July 12, 1907. The error in direction and level was extremely small. Note.—For the photographs of operations inside the Simplon Tunnel we are indebted to Mr. Francis Fox, M.Inst.C.E., and for help in their reproduction to Mr. W. L. Law and Mr. W. T. Perkins.