Rambles on Railways

by Sir Cusack P. Roney

As a rule, the tunnel mileage (except in one country only, Spain) is much less in proportion to total mileage on the various continental railways than it is in England. This is especially the case in almost all the more recently constructed lines, but more particularly so in Germany. Here, the ingenuity of the engineer has been exercised to avoid tunnels wherever possible, and not to seek them. We might cite many instances in proof, but limit ourselves to one, which must be familiar to many—the line along the left bank of the Elbe, between Dresden and the Austrian frontier at Bodenbach, through the beautiful Saxon Switzerland. There are, however, tunnels in Germany, the longest of which is that which has already been mentioned, the summit Tunnel of the Sœmmering Pass, 1,565 yards, just 195 yards less than an English mile.

There are long tunnels in France, both canal[130] and railway, and as regards the first-named class, our readers will hardly be prepared to learn that there has existed for forty-five years in France, an underground passage at Cunhardy called a tunnel, which is in length only 314 yards less than the Great Tunnel of the Alps; yet such is the fact,—the Norieu underground passage which forms a portion of the Canal de St. Quentin, is 13,128 yards long, or 7½ miles all but 72 yards. Its maximum depth below the surface is 86 yards. It is only 4 feet 11 inches wide and is without towing path. It was opened in 1822 at a cost of only £2. 12s. per yard. Seven years were occupied in its construction. But the most important canal tunnel in France, in respect of its width and elevation, is that of Rigueval, which is also on the Canal de St. Quentin. It is 6,237 yards long, 26 feet 2 inches wide, of which 5 feet 3 inches are for the towing path along which horse traction is used. The Tunnel of Manvages, 5,320 yards long, is on the Canal du Marn au Rhin. Of the two other long canal tunnels (both on the Canal de Bourgogne), that of Sousey is 3,873 yards long, 7 feet 3 wide. It has not a towing path. That of Pouilly is 3,630 yards long and 20 feet 2 inches wide, including a towing path of the width of 5 feet 3 inches. The cost of the Sousey was £9. 4s. a yard; of Pouilly £80 a yard.

The longest railway tunnel in France is that of La Nerthe on the Paris, Lyons and Mediterranean Railway, between Avignon and Marseilles. It is 4,638 metres (5,101 yards). It cost £90. 10s. per metre. Its shafts vary in depth from 65 to 623 feet.[131] There are twenty-four of these shafts, which are not over the centre of the tunnel, but about 30 feet on one side. They communicate with it by lateral galleries 10 feet wide, and as high as the tunnel itself. The shafts are all circular, about 10 feet wide, and have all been left open. The gradient from one end to the centre is 1 in 500—10½ feet in the mile. It then falls to the other entrance at the rate of 1 in 1,000. The tunnel of Blaisy on the same line, near Dijon, is 4,100 metres (4,510 yards). It cost £77 per metre. It had twenty shafts during construction, of which ten are now closed. Nine of the shafts are from 515 to 643 feet below the surface. They are not over the tunnel, but about 32 feet on one side, and connected to it by lateral galleries. The Credo Tunnel on the Geneva Branch of the same line 3,949 metres (4,344 yards), £65. 12s. per metre. There are several other long railway tunnels in France. That of Rilly near Rheims, is 3,500 metres long. There were nine shafts during construction, of which four were closed when the railway was opened. Although lined with masonry throughout, the thickness being 20 inches in compact chalk, and 32 inches in that which was seamy, the cost was only £28. 15s. per yard. Hommarting Tunnel (Chemin de Fer de l’Est), is 2,780 metres long, Pissy Poville, 2,400 metres; Tarare is a very long one but we are not sure of its exact extent. The Tunnel of Arschwiller, on the Chemin de Fer de l’Est, is 2,678 metres, and is close to the tunnel of the canal from the Marne to the Rhine, named on the previous page the Tunnel of Manvages. In fact, where they enter the mountain they are at the same level, and a double arched entrance—the intervening pier being only 22 feet thick, and the arches precisely similar—receives them both. The canal tunnel was completed before that for the railway, which latter diverges from the line of the former at the rate of 26 feet in 1,000, so that at the end of the railway tunnel it is 60 feet from that of the canal. The canal then makes a bend and presently crosses over the railway tunnel, as it has a descending gradient of 1 in 200, and at what may be called its diverged entrance, it is 44 feet below the level of the canal. The railway tunnel took nearly eight years to construct at a cost of £38. 10s. per metre forward.

There is also a large number of tunnels from 500 to 1,500 metres long. The price per metre forward varies nearly as much as in England, its maximum being £95, that of Batignolles, near Paris, on the Chemin de Fer de l’Ouest, a short one, only 333 metres (366 yards); minimum £30, that of Terre Noire 1,641 metres, on the Paris, Lyons and Mediterranean.

The longest railway tunnel in Belgium is that of Braine le Compte, 641 metres (705 yards). It cost £46 a metre. There are altogether eighteen tunnels along the 15½ miles of picturesque line of railway between Liege and Verviers; they are all short, none exceeding 400 metres in length; their cost was exactly £50 a metre forward. There is only one long tunnel in Switzerland, that of Hauenstein near Olten, on the railway between Basle and Berne, its length is 2,731 yards, and, notwithstanding the numerous difficulties which attended its construction, its cost was only £80 per yard. It might be expected that in an undulating country like Switzerland there would be a great many tunnels on its railways; such, however, is not the case, the larger proportion of the railways are constructed in the comparatively level valleys, and when engineers come upon rough ground, as a rule, they prefer stiff gradients to very expensive works. This, however is not always the case; witness the passage of the Jura from Pontarlieu towards Neufchatel; here there is the combination of expensive works with a steep ascending and then a steep falling gradient. These might have been greatly alleviated, if not altogether avoided, by a tunnel of comparatively short length; the engineer, it is said, wished to erect for himself, in this work, a monument perennius ære. He has succeeded.

The longest tunnel upon a railway in Italy, now open for traffic, is on the Giovi incline, near Genoa, 3,225 yards, or five yards over two miles. The longest of the two on the Brachia pass of the Apennines, between Pistoja and Poretta, is (as already stated) 3,300 yards; the length of the next longest, on the same pass, is 2,860 yards. A tunnel longer by a few yards than that on the Giovi incline, is in process of construction on the branch which is to connect Naples by a direct line with the Adriatic. The tunnel Maggioni, between Florence and Rome, is 1,170 metres (1,287 yards) long.

The natural undulatory, in many places almost mountainous, character of Spain, has rendered necessary the construction of numerous tunnels on Spanish Railways. The following is an abridgment of much interesting information on this subject, published by the Spanish Government last summer, and translated into French a few weeks ago.

On the line from Madrid to Saragossa, the length of which is 213 miles, there are twenty-six tunnels; the most important of them is Horna, 1,010 metres. The total length of these twenty-six tunnels is 4,791 metres, or 3⅝ miles. On the Manzanares to Cordova Line, the length of which is 243½ kilometres, there are thirteen tunnels, the longest of which is 1,025 metres; their total length 3,092 metres. The Albaceta to Carthagena Line, is 154 miles long; the chief tunnel is that of Almadenes, along the gorge of the same name, its length is 1,056 metres. There are four short tunnels on this line, all in the vicinity of the gorge; their combined length is only 393 metres, making, with the tunnel of Almadenes, 1,449 metres.

The Northern of Spain—Madrid to Irun—is 399 miles long. Although it is not the longest, it is probably the most important railway in Spain, traversing nearly throughout its entire extent, a difficult, and, at places, an extremely hilly country, and finally terminating at the Pyrenees, where it meets the Bayonne and Irun Railway. Thus, on the section from L’Escurial to Avila, 44 miles long, there are sixteen tunnels, the total length of which is 4,408 metres, all of which are associated with numerous extremely difficult works of art in their immediate vicinity, some of the viaducts varying from 95 to 135 feet in height, with other proportional dimensions. It is in this section that the Guaddarama Mountains are traversed, and, until the locomotive crossed the Mont Cenis the summit of this railway was the highest in Europe, 4,505 feet above sea level. On the section between Otzaurte and Beasain, 33 miles long, there are twenty-three tunnels, the total length of which is 10,351 metres. Some of the works of art on this section are magnificent in their character and construction. The tunnels on the other sections of the line are not so numerous; nevertheless, they are altogether fifty-eight in number, with an aggregate length of 22,160 metres, exactly 14 miles.

Turning from the most difficult Spanish railway in point of construction, to the easiest for the greater part of its extent, the Seville, Xeres and Cadiz Line, the length of which is 103 miles, we find that there are no tunnels upon it, although on the section between Xeres and Cadiz there are several extremely difficult works of art.