The bridges on the railroads
The history of the origin and classification of railway bridges
Much trouble delivering to the builders of railroads large and small rivers, like mountains impossible to see side. Help them to cross the bridges. Raised pillars over the water, they serve as a secure base for the railroad. On the approaches to the river embankment erect, she then picks up the railway track to the bridge.
The bridges are divided into beam, arch or suspension. The construction of bridges, especially big ones, is time consuming and complex task, requiring precise engineering calculations, a high professional skill. Along with viaducts, overpasses and flyovers bridges are one of the main types of artificial structures on the railroad.
The first railway bridge girders with cast of the original form was built under the leadership of J. Stephenson in 1824 in the UK on line Stockton—Darlington. In 1829 Stephenson also built the first “slash” crossover in Rainhill (Rainhill). Before starting construction, Stephenson manufactured and tested a model bridge made of wood in full size.
The earliest suspension bridges appeared in America. The most famous is built in 1852-1856, bridge across Niagara (Niagara). The superstructure of this bridge had a length of 251 m and a height above the water level of 74 m.
On the Saxon-Bavarian railway was built the bridge across the river Belaya Soroka, near the city of Aceta (Jocketa). First the bridge wanted to build in four levels, but due to construction difficulties was limited to two.
In the middle of the XIX century a railway was built connecting Venice to the mainland, located at a distance of 4 km from the Lagoon was blocked by two bridges: train for two ways built in 1841-1846. and walking the length of 4070 m and a width of 20 m, built in 1931-1932 Railway bridge, inaugurated in 1846 had a length of 3601 m and consisted of 225 on arches 75 000 piles, buried in the bottom of the lagoon.
Railway bridge built on the line Augsburg— Nurnberg (Augsburg—Nurnberg) over the river ISAR in the 1850s was restored in 1912.
Overpasses became known as the bridges are built over roads or Railways to ensure the movement of vehicles or pedestrians on the crossing paths, i.e. two levels. The overpass for the railroad was built through the valley of the Sankey tank (Sankey) is already on the line from Manchester to Liverpool. The first pedestrian overpass appeared on the line from Paris to Orleans in 1843
Overpass esta in French-cade — pile, beam — construction bridge type, is arranged for the passage of vehicles at a free space beneath the spans. Trestle suit instead of large mounds in the cities where they are less hampered by the streets and not impede the passage and the passage beneath them, and on the approaches to large bridges over rivers with wide floodplains of flood water.
To build a bridge on the railroad for each river and stream is not required. Small rivers and streams flow through the roadbed of the railway through the pipes.
From the history of bridge construction
In prehistoric times by primitive people for crossing water obstacles used fallen, and later a specially laid across barriers of trees.
The first mention of artificial structures belong to the early 3rd Millennium BC In ancient Egypt, Babylon and Assyria developed the construction of artificial structures, which flourished later in Ancient Rome.
During the new era and then in the middle ages the profession of bridge Builder enjoyed universal respect. An example is Trajan’s column in Rome. The Roman ruler Marcus Ulpius Traianus (Markus Ulpius Traianus), known to history as the Emperor Trajan, 113, may 18, visited the Senate, where he gave a speech. In memory of this event, the Senate decided to build a stone column. A lot has changed since then, but Trajan’s column with a height of 38 m centuries later, remains a historical monument. On the column depict not only episodes of Trajan-Dacian wars, but the pontoon bridge, and major bridge over the Danube, built by order of Trajan Apollodorus Damascus (Appolodorus) in 101 g. the Emperor praised the construction of these structures.
The network of roads with many artificial structures have reached in Ancient Rome, 80,000 km. Only in Rome itself there were about 500 km of water pipelines with a lot of aqueducts, tunnels, retaining walls, etc. Dozens of such buildings have survived in the territories of Italy, France and Spain.
The first historical mention of the building of bridges in Russia refer to 997, But the bridges built previously. In the “Russian truth” (1020) mentions that in the army of Grand Prince of Kiev Yaroslav the Wise (C. 978-1054) were special units “mosti-ers”, who were engaged in the construction and repairs of bridges, crossings, etc.
At that time the main material used in bridge construction was a tree. The oldest wooden bridge is the bridge through the river Euphrates in Babylon, built over 2000 years BC the Supports of this bridge were made of brick, and the superstructure is made of cedar. In 607 BC in Ancient Rome through the river Tiber was built a wooden “pile” bridge. To this period belong the grandiose pontoon bridges over the Bosphorus and the Danube, built for the troops of the Emperor Darius. Wooden girder bridge on stone piers with a length of over 400 m across the Rhine was built by Caesar in 55 BC in just 10 days. The Emperor Trajan for the transition of the Roman legions from Dacia in the Danube lands was ordered for one year to build a bridge across the Danube. It is this bridge over the gorge “Iron gates” erected in the valley of the Danube. This unique wooden arch bridge with a total length of about 1 km were spans of 36 m (!). Truss wooden arches were lying on a rectangular marble pillars. Similar bridges later (400-700-s BC) were built in Cologne and Mainz (Mainz).
Were often built and pontoon bridges. In Russia under Vladimir Monomakh was built floating bridge across the Dnieper; in the time of Dmitry Donskoy — through Volga. Later, along with wood, and built stone bridges, heavier and durable.
Among the architectural monuments of the middle ages may be mentioned the stone bridge in the South of France through the river Lot (Lot) in Coarse (Cahors), built in 1308-1355, Bishop Raymond Panelli. The bridge consisted of six Gothic arches, a feature of which was the fact that piers are built three watch towers with a height of about 40 m each. These towers were used as defensive structures. According to the legend of success in the construction of the bridge provided the Bishop friendship with the devil.
Interesting bridge over the river rhône near Avignon (Avignon), built in 1177-1185. Holy Benezet (Saint Benezet) — one of the inspirers of the creation of Monastic of the society of French “bridge brothers”, which was approved in 1286 Bridge had 21 arch with spans of 34 m at a height of 13 m. all the foundations of the piers were of a width 8 and a length of 30 m. the Bridge had triangular bulls head icebreaker. The 1669 flood destroyed a significant portion of the bridge. Till our days survived only four arches, considered to be an architectural monument and serve as a symbol of the city of Avignon.
In 1225 g. over the river Werra near the city Kreicburgas (Creuzburg) in Germany a bridge was constructed with a chapel (Werrabrucke), which was partially destroyed in 1945 and fully restored in 1950
The first metal bridges are mentioned in China, where else BC they used bronze and cast copper. The widespread use of metal in bridge construction applies to the second half of the eighteenth century when the industrial revolution in England allowed us to obtain sufficient amount of homogeneous iron.
The first cast iron arched bridge (extant, by the way, to the present day) was built in England in 1774
The bridge consists of spans, which are the basis for the path, and the pillars that support the superstructure and transmit the pressure on the ground. The bridge with approaches, fortification and regulatory structures and the vertical channel of the river is a bridge. Abutment of the bridge are called abutments, and the intermediate — “bulls”. Bridge bearings is divided into spans. Supports consist of a base and a visible part (body) and are monolithic or modular. The footings can be constructed at a shallow location, strong soil on a natural basis, and in soft ground — on stilts.
The scheme of the bridge
1 — foundations, 2 — stationary bearing part; 3 — span structure, 4 — movable support part 5 —”bulls”, L — total length of bridge, l p , is the estimate of the span l 1 +l 2 + l 3 — hole bridge networks — horizon high waters; SMOA — horizon low (medium) water