THE PIERCING OF ST. GOTHARD.

Bruce Herald, Volume XIII, Issue 1209, 4 June 1880, Page 6

THE PIERCING OF ST. GOTHARD.

One of the great engineering works of the present century, the piercing of a second great tunnel through the Alps, was carried to a successful issue on the 28th of February , when the workmen from the two ends of fche excavations under the St; Gothard were able to shake hands with one another miles away from the surface of the earth. Modern progress in engineering science has stripped such enterprises of much of their uncertainty, and, therefore, the conception of works like the St. Gothard tunnel appears to us now a matter hardly deserving particular attention. When, however, between 1850 and 1860, an Italian and a Swiss engineer, Locchini and Mueller, first examined the topography of the St* Gothard, and reached the conclusion that the undertaking was practicable, their statements were received with much doubt. Their work was continued by Wetli, and later, in 1863, Dr A Escher, prominently connected with the Swiss railroad system, caused more extended and elaborate, technical and financial examinations to be made by engineers Gerwig and Berkh, whose labors resulted ia the recommendation of Airolo, on the Italian side, and Goeschenen, on the Swiss side. Meanwhile the Italian Government decided to enquire into the feasibility of the plans proposed, and in 1869 united with the Swiss and German Governments to determine by treaty the basis upon which the three countries would co-operate in pushing the enterprise to an issue. The -Franco-German war caused a suspension of these delibera« 1 tions, and it was only iv October, 1871, tbat the organisation of the St. Gothard Railway Co. became possible. Early in the spring of 1872 bids for the execution of the tunnel were called for. Seven in all were received, of which two only were seriously considered — one made on the part of an Italian company, the other coming from M. Louis Favre of Geneva. The latter was accepted on the 7th of August, 1872. It was somewhat modified during the year following, so that the contract price rose to 9700,000 dol., the time for completion being limited to eight years. The agreement entered into by the parties provided for a penalty of a little less than lOOOdol a day during the first six months following the 7th August, ISSO. If the tunnel should not be completed at that date, this penalty is to be doubled for the succeeding six months, and if the tunnel is not opened for traffic by the first of October 1881, a security of 1,500,U00d01s deposited by M. Favre, would be forfeited. The early connection of the work prosecuted from boih sides will probably secure the contractors against loss by these provisions, and possibly the bonus of lOOdols a day for completion before the 7th of August may be obtained for a short period. It must not be forgotten, however, that while the advance heading i 3 now carried through, the other portions of the work are atill considerably behind. As in all large tunnels, thu work in the St. Gothard advances in sections. Following the Belgian system, a heading near the top of the arch is driven in advance, and this is followed, further back by an enlargement to both sides bringing out the full section of the upper part of the tunnel. The lower bench is then proceeded wich in a similar manner. The tunnel section was thus taken out in two levels at the Goeschenen side, while at the Airolo side three were fouud to be necessary. Excavation is followed by timbering, and this is succeeded by the archiug, so that, entering the tunnel at one porta), each stage is successively passed through. The dimensions of the St. Gothard tunnel are large enough to accommodate a double track of standard gauge, the widtli at the level of the sleepers being 24. 93 feet and the height 19.68 feet. The tunnel is on a tangent for the 1 greater part of its length, only 476 feet at the Airolo end being on a curve of 84 feet radius. The total length, when completed, will be 48,857 feet, or 9.26 miles — cons siderably more, therefore, than either the Mont Cenis (40,084 ft), the Hoosac (25,040 ft)' or the Sutro (20,370 ft). Although the tunnel passed through hard ground throughout, and at Airolo end through a wet and difficult formation, its cost was considerably less than that of earlier works of the same kind, owing to a certain extent, to improved methods of excavations, which also largly reduced the time. Tne i Mont Cenis tunnel, which may best serve to show the advance of modern tunnel work — because cost of labor, etc. , were not so widiy different — cost 15,000,000 dols. and required thirteen years, while the Hoosac cost 13,000,000 dols. and took eleven years from the time when work was properly begun. It should not be forgotten, in the case of the latter work, that the cost cf labor, machinery and materials is vastly greater tban it is in the case of the European enterprises cited. Among the chief egineering features adopted in the construction of the St. Gothard was the use, almost from the outset, of rocks drilling by machinery and blasting with high explosives. Water power being available, M. Colladon, a well known Swiss engineer, was called upon to design an extensive aim compressor plant, which at the present time comprises nineteen compressors, driven by turbines at each end of the tunnel. Experience at the St. Gothard has contributed much toward the introduction of power drills, and various types of the Soinmeiller, Dubois»Francois, McKean and Ferroux drills were successively used, by the aid of which a monthly advance of from 400 to 440 feet was reached, in rock composed chiefly of granitic gneiss and various granitic aud micaceous schists. The commercial importance of this great work for Central Europe cannot be over estimated, while for Switzerland its cornple tion has become a question of vital import* tance, the piercing of Mont Cenis having diverted much of thu traffic to French roads. The St. Gothard railway forms the shortest linu of transit between the Mediterranean and the valley of the Rhine, and will be one of the greatest arteries of trade of the con<tinent, carrying all the transportation and travel between Italy and Switzerland, northeastern France, western and central Gcr--many and northern Europe, It will probably carry the great East India mail between Great Britain and her eastern empire, via Brindisi, Italy and the Suez Canal. Two ot the great Alpino passes have thus been superseded by th;-; work of modern engineer- j ing, and it is only a question of time when I Austria will follow the lead of'hei* neighbors and commence the work of piercing the | Simlon.— ' Iron Age.' |