Engineering Wonders of the World
Volume III

152 ENGINEERING WONDERS OF THE WORLD. SKETCH MAP SHOWING THE POSITIONS OF THE CHIEF ALPINE TUNNELS AND THE ROUTES OPENED UP BY THEM. strokes per minute. Moreover, dynamite was substituted for gunpowder in blasting. These improvements, added to the experience gained from the earlier tunnel, rendered prog- ress much faster than at Mont Cenis — the daily advance a eraging 6’01 yards—and re- duced the cost to £142, 13s. per yard. Bad ventilation caused so much sickness among the men that air loco- motives were introduced to remove débris from the work- ing face. On New-Year’s Day, 1882, the tunnel was completed, and shortly afterwards Switzerland and Germany possessed easy communication with Genoa the summit. From first to last the physical conditions were most difficult, the valleys being narrow and precipitous, and the gradients severe. The approaches are, in fact, as won- derful as the main tunnel itself. The exact length of the tunnel is 16,295 yards. Its section is the same as that of the Mont Cenis. From the northern portal the rails run for 8,127'8 yards up Gradients. . n. . J an incline or 1 in 172, to a level stretch 180 yards long at the centre; which passed, they encounter a decline, 7,970’3 yards long, of 1 in 1,000 to Airolo, at the southern entrance. Work on the tunnel began on September 13, 1872, at the southern end, and on October 24 at the northern end. The system adopted was to run top galleries in ad ance and break them out laterally and downwards to the full section of the tunnel. The Sommeiller air-drills used on the Mont Cenis Tunnel were replaced by the more efficient Ferroux drills, making two hundred Improved Drills and Explosives. and other Italian ports. The time occupied in driving the tunnel had been Success» 88 months, as compared with. the 157 months of the Mont Cenis, though the St. Gothard was the longer of the two tunnels by well over a mile. The cost of this tunnel was rather more than £2,300,000 sterling. While the St. Gothard Tunnel was still in progress, the Austrian Government had put in hand a project for giving Vienna rail com- munication with Paris through Switzerland, as an alternative to the partly German route vid Salzburg, Munich, Stuttgart, and Strass- burg, by prolonging the line to Innsbruck through Landeck to Feldkirch, near the Swiss frontier. Westwards of Landeck the Alps assert themselves, and the line has to climb up gradients of about 2 per cent. and round numerous sharp Arlberg1 . « • Tunnel. curves. At St. Anton it en- ters a summit tunnel, 6| miles long, running due east and west. For 2| miles the gradient