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The rail sections can have a length of even 80 meters; in this case their manufacture and transport presents greater difficulties. Their thickness, and consequently their weight, will vary according to the use to which they are destined; generally they have a weight from 30 to 75 kilograms per meter. An important rule in the installation of rails is to leave between the sections a separation of some centimeters, because the variations of temperature will cause expansion and contraction in them. It is precisely this separation between sections what causes the repetitive, characteristic noise that we perceive when traveling on train; and naturally, the length of the sections will determine the frequency of the noise. To connect the rail sections to each other elements such as bondbars, clamps and bolts are used.

Railway tunnel
Tunnel built in the mountains of Colorado.

Two rails, installed side by side above the sleepers, form what we call the railway or railroad. Albeit this one is not very difficult to install, there are some aspects that must be taken into account. In curves, for example, apart from placing shorter rails and placing the rails of the outer side in a more raised position, it is required to adopt the slightest curvature possible to reduce to the minimum the centrifugal force, which otherwise could put the trains in severe risk of derailment. Regarding the width of the railway - known as gauge -, a convention between the European countries set in 1884 a tolerance term from 1.435 to 1.445 meters and adopted this as the standard railway width. To this convention did not adhere Russia, Spain and Ireland, which adopted greater or lesser widths. A reduced width is less costly, regarding both installation and service, allowing as well curves of lesser radius which are more suitable for mountainous terrains.

Pneumatic drill
One of the first types of pneumatic drill.

To conclude these paragraphs it would be worthy to mention the smallest railway, in which rails and sleepers are assembled to form a single, portable frame. This system, called Decauville after its inventor, uses rail sections of about five meters in length that are fixed to metallic sleepers. The intention was to produce prefabricated sections of light and narrow railway, easy to disassemble and transport. The gauge of the railway was initially 40 centimeters, but it was later increased to 50-60 centimeters.

Steam locomotive

The railway on the mountain

In the middle of the 19th century the Austro-Hungarian Empire was crossed by efficient railway lines linking Vienna with other cities, but all of these lines were built in plains, because, like in other countries, the problem posed by steep slopes had not been solved yet. Emperor Franz Joseph I, due to military requirements, required a faster link with the territories under his command, and because of this he projected a direct communication between Vienna and Carinthia. A project from the engineer of Venetian origin Karl von Ghega was well received by the Emperor; the railway would have to cross the Semmering, a mountainous region with an altitude of 980 meters, making use of very daring viaducts in a route of 41 kilometers in length.

The picturesque line connecting Villach, Lubiana, Graz and Vienna was finished in 1854 and happily inaugurated by the Emperor himself. It had 15 short tunnels and the train had to overcome a grade of 500 meters, with slopes of 25 per 1000. For this line it was necessary to research special locomotives that were capable of dragging their convoys along notable slopes, and for such purpose a contest was opened. The winner was the company Maffei, and the locomotive was baptized as "Bavaria". Once achieved that trains were able to climb to the mountains, it was proposed to cross these directly to save kilometers and overcome difficulties that otherwise would be insoluble. So, the most important mountainous massifs began to be perforated through audacious construction works that are worthy of admiration.

The railways with the highest altitudes in the world were built not in Europe but in South America. These are some important ones, ordered from higher to lower elevation (in meters): the Bolivian (4880); Lima-Orova, in Peru (4834); Arequipa-Puno, in Peru (4770); Arica-La Paz, in Chile (4264); Durán-Quito, in Ecuador (4100); Mendoza-Santiago, in Argentina (3489); Jungfrau, in the Bernese Alps (3457); Denver-Río Grande, in Colorado (3453); Djibuti-Addis Abbeba, in Ethiopia (2606); Darjeeling, in the Himalaya (2170); and the Albula-Bernina, in Switzerland (1823).

And these are some of the longest railway tunnels, ordered by length (in meters): Huntington Lake, in California (21760); the Simplon, in Switzerland-Italy (19728); Lotschberg, in Switzerland (14606); Otira, in New Zealand (8450); the Trans-Andean, in Argentina-Chile (8100); Hoosac, in Massachussetts (7640); and Sutro, in Nevada (6000).

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