Since the completion of the Mont Cenis Tunnel, a still greater piece of rock boring has been begun and finished in the great tunnel of the St. Gothard Railway. The construction of a railway to connect Italy with Switzerland, was a project conceived as far back as 1838, when the first railway company in the latter country was constructed. The route of the proposed line was a matter of much debate, not alone on account of difference of engineering opinions, but also by reason of the various competing interests that would have to be reconciled and induced to co-operate in the work. The St. Gothard route was only one of the several schemes that were advocated, and the first decisive step appears to have been taken at Lucerne, where, in 1853, a meeting was called by the authorities of the canton to consider the merits of the project; the result being that the Lucerne Government addressed to the Federal Council a representation of the advantages this route would afford. More discussion ensued, and it was only when Switzerland appeared likely to have no share in the traffic between the Milan district and the more northern parts of Europe that, in 1861, the partizans of the St. Gothard route appointed a provisional committee to take action in the matter. This committee had plans prepared, and sent a deputation to obtain the assent of the Italian Government. The canton of Tessin, through which the projected line, or its then surviving rival, was designed to pass, became a lively scene in the game of speculation, for promoters rushed in to secure, if possible, concessions which they might sell at a very advanced price to the winning party. For this purpose came to that poor Swiss canton Jews and Christians from every land. The St. Gothard route gained the day, and a Union was, in 1863, formed by the concurrence of the two principal Swiss railways and fifteen of the cantons most interested in the scheme. Difficulties and delays were, however, encountered before the necessary compacts could be concluded with the neighbouring states—and then there came the war of 1867. So that it was not until the latter part of 1872 that the construction of the line was actually entered upon. Before the great work of piercing the St. Gothard had been completed, the undertaking was embarrassed by financial difficulties arising from the fact of the lines on the Italian side costing more than double the estimated amount. The Swiss Government, however, voted a special subsidy, and the work, which had been suspended for a while, was proceeded with; much attention being paid to its economical prosecution. In 1881, when the line was opened, the mails were carried between Zurich and Bellinzona in seven hours, instead of in thirty hours as previously required for transit by the excellently appointed mail carriages under the Federal Administration.
Fig. 187a.—Map of the St. Gothard Railway.
Besides the great tunnel, the St. Gothard line has some unique devices in railway construction which cannot fail to interest the reader. Several of the passes over the Alps have been made use of from time immemorial. We know that Hannibal led his Carthaginian hosts over one of them, and that they have been traversed by Roman legions, as well as by Germanic hordes. But, although the St. Gothard is the most direct of all the routes, it never afforded a passage to armies or migratory tribes. The road through this pass was not formed by the use of any elaborate appliances for overcoming the natural obstacles: it was rather the work of simple peasants and mountain shepherds, with such rough constructions in wood as might give a sufficiently secure passage across the torrents and gorges. The old road keeps beside the Reuss from the head of the lake of Lucerne until it reaches the highest level of the pass, where the water-shed occurs. It then descends steeply, with many twists and windings, to the banks of the Ticino, and it follows the course of this river to its embouchure at Tresa, on Lago Maggiore. The railway follows the same course, except that it cuts off the higher part of the pass by the great tunnel piercing the mountain. The scenery throughout could, perhaps, be nowhere equalled for the variety of its wild grandeur.
The great tunnel of the St. Gothard passes from Gœschenen, on the Reuss, beneath the col of the pass, and emerges close to the village of Airolo, on the banks of the Ticino. The length of this tunnel is rather more than nine and a quarter miles, so that it is about one and a half miles longer than the Mont Cenis Tunnel. Its northern end is 3,638 feet above the sea level; its southern end is higher, namely, 3,756 feet; but there is an intermediate point in the tunnel higher than either-–3,786 feet—and from this there is a uniform incline in each direction. The tunnel is 300 yards beneath the lowest part of the valley of Andermatt, and the summits of the mountains it traverses are at least a mile above it. The motive power by which the rock-drilling machines used in driving the tunnel were actuated was, as in the case of the Mont Cenis Tunnel, compressed air; and the power used for compressing the air was, in this case also, a head of water,—but this was not applied in the same way. The waters of the Reuss at the northern side, and those of the Tremola and of the Ticino at the southern side, were taken at a considerable height in very large cast-iron pipes, and were made to act upon powerful turbines that gave motion to the compressing machines. These were capable of compressing the air so that its volume was reduced to one-twentieth, and the pressure it then exercised would, of course, be equal to that of twenty atmospheres, or about 300 lbs. on the square inch,—or more than three times as much as was made use of in the Mont Cenis Tunnel. The compressed air, carried through pipes to the head of the workings in the rock, was there allowed to exert its force on the pistons of the perforators in the manner already described. There was, in fact, a continual repetition of exactly the same cycle of operations of boring, charging, firing, etc., that are mentioned on page [355]. A large quantity of the compressed air was always allowed to rush into the work immediately after each blasting, in order that the smoke and other products might be driven out and the atmosphere rendered fit for respiration. In attacking the mountain simultaneously from each side it was, of course, essential that the tunnels should be driven in precisely the same direction, and therefore the positions of the points of departure had to be determined by very careful surveys. At Gœschenen, the gorge of the Reuss did not naturally admit of a sufficient distance of vision to fix the direction with the required accuracy, and it became necessary to pierce a thick mass of rock with a special tunnel for the purpose of taking a sight sufficiently far back. At Airolo, again, the tunnel had to enter the valley by curving towards the village; and here a provisional gallery had to be driven in the straight line.
PLATE XVI.
THE NORTH MOUTH OF THE GREAT TUNNEL, ST. GOTHARD RAILWAY.
Several contractors competed for the work of constructing this great tunnel, and it was at first supposed that an Italian company, which was managed by some of the principal engineers engaged on the Mont Cenis, would be almost certain to obtain the contract. The promoters, however, intrusted the work to a private individual, M. Louis Favre, of Geneva. This gentleman undertook to complete the tunnel in eight years, at the price of 2,800 francs per mètre for the work of excavation merely, exclusive of masonry, etc. This cost would be not far from £101 per English yard. The contract was signed on August 7th, 1872, and on September 12th of the same year M. Favre commenced operations at the southern end, and the work at the northern end was begun on October 9th following. The operations were carried on with great energy, and even during the period of the Company’s financial difficulties there was no stoppage of the works between Gœschenen and Airolo. It has been suggested that it was largely due to the regular and successful progress of this great piece of rock boring that the Company were enabled to re-establish themselves on a basis that ensured the completion of the whole undertaking. The contractor, on his part, did not fail to encounter many physical difficulties. At the southern end much trouble was caused by torrents of water gushing from the soil, many of these being of great volume and force; in fact, the work was here carried on for nearly a whole year in the midst of water—for the ground for the first mile consisted of glacial and other deposits, which were intersected by subterranean water-courses. Reaching the solid rock was here a relief. But at Gœschenen little of loose formation was met with; but the rock encountered was of extreme hardness—consisting, indeed, of almost pure quartz, which had the effect of quickly blunting the points of even the best tempered tools. But another kind of difficulty had to be overcome when the workings got beneath the vale of Urseren. Here, at several places, layers of argillaceous matter were found between the masses of hard rock. These layers were easy enough to pierce through, but on account of the pressure of the rocks in which they were interspersed, they were squeezed out and gradually protruded within the tunnel, which would soon have become entirely obstructed. At first a very massive lining of timber was tried, but it was soon found that this must be replaced by a solid vaulting of stone. The first vault failed to sustain the pressure, and so did the second, although the thickness of the material was more than a yard. In some places these operations had to be several times repeated, and from this cause the cost of parts of the tunnel has been nearly £1,000 per yard.
Fig. 187b.—The Uppermost Bridge over the Maïenreuss.