The 20th century was the time of the great luxury trains, the great express trains and the famous transcontinentals; all the manufacturers, either American or European, demanded from their own teams of engineers, draftsmen, technicians and operators a greater and more intelligent collaboration, oriented to improve the production and adapt it to the requirements of the moment. In 1964 the railways around the world reached not less than 1236000 kilometers, distributed like this: 453000 in North and Central America, 108000 in South America, 400000 in Europe, 175000 in Asia, 70000 in Africa and 50000 in Australia.
Italian locomotive Model 691, introduced circa 1930.
The stations
The station is the heart of the railway traffic, and the railway infrastructure of a country can be compared with the circulatory system on the human body. The most important stations do not know rest. To have an idea of the gandiosity of their traffic one can look at the most important railway junctions such as New York, London, Paris, Milan or Cologne. In these large stations there is little difference between nighttime and daytime. In general, a train station comprises all those facilities that manage the arrival, departure, transit and composition of trains. Stations are always built in a flat, level surface, because the vehicles, whether locomotives, cars or freight wagons, have to stay stationed without being braked.
Locomotive of the class T1 4-4-4-4 Duplex Drive, introduced in 1942 for the express trains of the Pennsylvania Railroad.
When the distance between two stations is about six or seven kilometers, no more than 15 or 20 pairs of trains can transit; a pair refers to one going and one returning train. In those stations fitted with double tracks up to 90 pairs of trains could transit, if conditions are favorable. Not every station serves the same purpose. Basically, we can differentiate three types of stations: terminal stations, which are used for changing the course of trains; transit stations, through which trains simply transit; and switching yards or shunting yards, where trains are assembled or disassembled as required. Each of these stations, regardless of their importance, apart from the transit tracks, is provided as well with auxiliary tracks or side tracks for empty cars and wagons that are in expectance of being used.
In the terminal stations the tracks are truncated and departures have always a direction which is opposite to that of arrivals; trains end and start their march here. The largest stations have a particular structure based in a wide tunnel or covered terminal gallery which gathers all the tracks and in which all the services end. Transit stations are those where trains arrive, pick up travelers or freight and then leave. Switching yards are constituted by particular facilities whose purpose is to decompose and recompose the convoys - wagon by wagon by means of small locomotives built for that purpose - according to what is required. These facilities are very different from the normal stations; they comprise tracks for arriving trains, tracks destined to the reorganization of convoys according to the different directions or stations, and also other tracks to park the already formed trains in expectance of their departure.
French Diesel-electric locomotive, whose maximum speed is about 140 kilometers per hour.
The classification of stations is made as well based on their importance: small, medium and large. Small stations are generally for transit only, as they have one or two tracks and a single sidetrack, necessary to allow crossings, and a small platform for operating freight. Medium stations are provided with additional tracks, either transit tracks or side tracks, a better platform for operating freight and also a railway yard for storing locomotives and a storage for accessories. Large stations are abundantly provided with every kind of facilities and services.
In terminal stations, to avoid obstacles and nuissances in the communications of the cities, tracks are placed at a higher level than roads, crossing them by above. These stations are usually divided in two or three sections by pedestrian crossings. The international stations of the largest railway junctions must be equipped, more than any other, with effective recomposition means and links with the different services, while in frontier stations are indispensable the facilities for customs inspection and a rigurous security service against smuggling.
Engineering works in the railway
Which are these works? Simply put: tunnels, bridges and viaducts. The first ones were already mentioned in former paragraphs so there is no need to retake the matter. So in this section only the other two will be mentioned. Railway bridges are made either of masonry or steel (the most modern ones), but rarely of both materials simultaneously. Both masonry and steel offer great robustness, but the second one can present a lighter and slenderer line. Masonry bridges were mastered by the Romans already two thousands of years ago, but modern bridges are made exclusively of concrete, preferably of the reinforced type. Bridges in general can have from one to multiple arches or spans. Viaducts are essentially bridges, but longer and hence more audacious. They are made to cross entire valleys, connecting the slopes of two mountains with a structure of multiple arcades with very tight arches to provide a greater robustness to the construction.
Unites States was the first country which built audacious steel bridges; one of the most notorious because of its length and structure is the Poughkeepsie crossing the Hudson River, built for the Pennsylvania Railroad, which has a length of 1500 meters and five arches with a span of 160 meters each. Also in United States, an international bridge of not less daring conception linked the country with Canada, above the Niagara: it was the New York Central Great Western, finished in 1856, with a length of 256 meters and a height of 76 meters; apart from the railroad there was a normal road running above. Later this bridge was replaced by an arch bridge made of steel. Now in Europe, an example of a typical viaduct could be that built in France from 1901 to 1909 by the company Cail, crossing the Sioule Valley at an altitude of 132 meters.