After the advent of railway transport, there was a need to stretch paths through rivers. Starting from this time, bridges intended for this type of transport began to be massively built around the world. They are also often erected when creating traffic intersections at intersections with highways. A modern railway bridge is a complex engineering structure that allows trains to overcome any obstacles (for example, ravines, gorges, canals, straits, and even urban infrastructure).
Start of construction in Russia
In 1773, Ivan Kulibin created a project for a bridge with trellised trusses, and after a quarter of a century, he first proposed the use of metal structures in the construction of such facilities. In the future, after the advent of railway transport, these ideas played a very important role in the development of domestic bridge building. Even then, the engineers were aware of the fact that it was necessary to make increased demands on such an object as a railway bridge , using more durable materials. Moreover, it was very important to ensure the protection of rolling stock from derailment.
At the end of the nineteenth century, the construction of bridges began to use metal, concrete and reinforced concrete structures, while their supports were built of stone. The shape and design of such structures subsequently repeatedly changed in connection with the development of technology and the emergence of new design solutions.
Types of railway bridges
Currently, railway bridges are usually classified according to several main characteristics. If the length is less than 25 meters, then they are considered small, from 25 to 100 meters - medium, from 100 to 500 meters - large, more than 500 meters - extracurricular.
Depending on the number of tracks, single-track, double-track and multi-track bridges are distinguished. According to the way the load is perceived, the supports are arched, beam hanging, frame, screw and combined types. Depending on the material used in the construction (the most common classification option), it is customary to distinguish metal, reinforced concrete, stone, wooden and combined bridges.
It should be noted that in the construction of all types, as a rule, combinations of various materials are used. The railway-road bridge is considered one of the most practical options among such objects. Its peculiarity lies in the fact that it allows you to pass both road transport and trains.
Wooden bridges
This variety was especially popular in the history of bridge building at the initial stage. This is due to the cheapness, simplicity and speed of construction. However, over time, it became clear that the wooden railway bridge is a fire hazard. Do not forget about his fragility and difficult care. In this regard, with the development of building technologies, such structures were gradually replaced by their stone, metal and reinforced concrete "brothers." In our time, the construction of this type is almost not practiced.
Stone bridges
Most of the existing stone bridges were built in the nineteenth century. Their main advantage is durability and strength. Moreover, they are insensitive to shock loads and increase the mass of trains. Nevertheless, the construction of railway bridges made of stone is a very time-consuming process. They can be built exclusively with short spans and on solid ground. With good moisture protection and proper care, they can stand for several hundred years.
Metal bridges
This variety is the most common in the world. Such a railway bridge is a structure in which only spans are made of metal. They are usually made from carbon steel grades or alloys. They are installed on concrete, stone or reinforced concrete supports. The main advantage of this type is the ability to mechanize the assembly and industrial production of structural elements. In addition, the spans can be installed by a hinged method or delivered by water. The only drawback of such a structure is its susceptibility to corrosion.
Reinforced concrete bridges
A reinforced concrete railway bridge over a river or other obstacle is a structure in which the spans are blocked by reinforced concrete structures. Their length, as a rule, ranges from 6 to 16 meters. At the same time, span structures with either a box section are usually used in spans. Supports are built from concrete or reinforced concrete.
A significant advantage of this variety is considered to be a long service life, as well as the relatively low cost of maintenance. As for the shortcomings, it should be noted only that the probability of chips and cracks due to the large mass.
Finland bridge
Finland Railway Bridge across the Neva is one of the brightest sights of St. Petersburg. It is one of the most important objects of the country's transport infrastructure and is one of the best in the world. The origin of the name is due to the fact that the railways of Russia and Finland are connected through it. In fact, the structure is two separate bridges that are adjacent to each other. The total length is 538.2 meters.
The Finnish railway bridge is movable. It was built in the period from 1910 to 1913. Its construction consists of four metal arched structures with a center piece. The bridge is considered a strategic object, so pedestrian traffic on it is prohibited. Such well-known engineers as G. Krivoshein, N. Belolyubsky and I. Alexandrov worked on the creation of the project. It should be noted that the construction plays an important role in the Russian economy, because with its appearance the railway communication of our country with all Scandinavian countries has significantly increased.