The classic metro tunnel in Moscow was built without an existing plan and without planning further development of roads. This led to some kind of chaos in the creation of the transport system, which is observed to this day. Currently they are guided by uniform rules, according to the document SNiP 32-02-2003.
How was the underground transportation system created?
It was decided to start building the first subway tunnel in 1931. Projects were created based on geological data. Reinforced concrete floors, which have still been preserved since then, were selected as materials for building at that time.
The subway tunnel was dug during the year, about 2 million cubic meters were shipped to create long mines. About 88 thousand tons of metal was spent on laying tracks and strengthening the vaults. The first buildings contained wooden structures and were equipped with massive insulating materials.
The subway tunnel turned out to be a costly project, it took more than 800 million rubles. Reinforced concrete vaults were later replaced by rubble masonry, but at that time the first construction option was more actively used. Inclined arches were reinforced with cast-iron tubing, roofing material, glassine glued with bitumen were selected from waterproofing materials.
Such designs require careful and ongoing maintenance, which is no less costly after putting the facility into operation. The Moscow Metro has worn out over the years and reconstruction is required, comparable in cost to the construction of a new tunnel. Therefore, new projects already contain recovery options after several decades and provide for the modernization of buildings.
Materials for the early subway
The construction of the tunnels was carried out by reinforced concrete floors, on which the outer layers of gravel, a layer of earth were applied. Vaulted floors provided high strength and reliability of structures. In open areas of the metro, the tracks were made with flat ceilings. Due to the lack of load, ground tracks were performed in a rectangular manner.
Tunnel construction is ongoing. Moscow is growing, and passenger requirements are also rising. Materials of early construction can no longer withstand the current speeds and intensity of movement of cars. But the round shape of the tunnels is still preserved to this day. This design is easier and more reliable can be isolated from the water that flows over the heads of citizens during a trip to the subway.
Moscow Metro has several underground levels. This is necessary to avoid intersecting lines. The design itself includes a direct passenger landing area and track tunnels. All branches are connected by transitions, which facilitates moving over long distances along a difficult route.
Subway device
Underpasses of metro stations have arched arches similar to tunnels. In places where platforms for boarding and disembarking passengers were equipped, support columns were installed. Here, the upper part was also performed in an arcuate manner.
Platforms tried to place between the tracks to facilitate the boarding and disembarkation of passengers. But some stations still have side platforms, such as the Komintern station. Service premises are often located under the platform itself, less often they are carried out into the area of the sockets, where there is a deep level of the laying of tracks.
Subway tunnels end with dead ends, where trains turn around to move in the opposite direction. There are also spare sumps for storing faulty wagons. On some routes, dead ends are mounted in the middle of the train. Such return routes are available at the Komsomolskaya station, it is located in the city center. This measure was required to ensure more intensive train traffic.
Features
The underground metro is laid at several levels, which helps to organize an effective route system. Stations are within walking distance of each other. Depth of laying varies in the following limits:
- Deep tunnels - the size is calculated to the level of the platform from the surface of the street and ranges from 16 to 35 meters.
- Surface tunnels are laid to a depth of 7 to 9 meters.
- Tunnels of medium depth are located between 9 and 16 meters.
The length of the stations is fixed, designed for 8 cars. And the width varies from 10 to 21 meters and depends on the depth of the tunnels. Each room is equipped with emergency lights in case of emergency. The lighting rate at the stations is organized according to the standard indicating the requirement of 100 lux.
The distance between stations varies from 500 to 1400 meters. Tunnels with lifts called escalators are tilted at an angle of 30 degrees to the horizon. Tunnels are heated by air from the hauls to the stations, thus eliminating the possibility of cooling tracks.
Room decoration
Some stations belong to the architectural heritage. Each of them has its own unique image. For decoration, materials such as granite and marble were previously used. Patterns filled the surfaces of columns, walls, vaults. Lighting was carried out by massive lighting devices.
Railway tunnels have a track gauge similar to the subway. If desired, an ordinary carriage can easily follow the underground lines. New metro routes often intersect with existing railways, which simplifies the modernization of the metro and the opening of new lines.
Tunnel lighting is provided around the clock. To eliminate accidents in the subway, signaling traffic lights with a red and green signal are installed. The prohibitive light cannot be overcome by the engineer. A self-locking system is provided when the brakes are activated independently when the car touches a special lever.
Automation
The transport tunnel is a complex structure equipped with dispatch systems, protective mechanisms, monitoring devices. Along the edge of the tunnel are feeding lines with a high DC voltage of 825 volts. The required value is produced by special substations located deep underground.
The lead car is equipped with 4 150 kW engines. The brakes of each car are powered by electric pneumatics. The automation system ensures the normal movement of trains with an interval of 1.75 minutes. The speed of each train is estimated at an average speed of 40 km per hour. The maximum possible for each car is 75 km per hour. Modern trains can follow much faster, but this requires laying new track lines.
Track upgrade options
To extend the operational capabilities of tunnels, constant supervision and interior decoration is required. This is done by accredited organizations with vast experience in carrying out this kind of work. For this, reinforcement of arches and bearing parts of tunnels is carried out.
Improving the water resistance of the foundation and finishing materials. Disposal of accumulated moisture in general drains. Changing the characteristics of adjacent soil. Replacing worn parts of reinforced concrete. For this, injection of solutions into the formed cavities, the latest waterproofing materials, and also moisture-resistant coatings are used.
Condition monitoring
To prevent accidents, the monitoring commission is constantly working, able to timely identify voids in the arches, cracks in the bearing parts of the walls and foundation. Recent developments in instrumentation help identify the smallest initial processes in concrete, metal parts.
For tunnel arches, it is important to stop the removal of soil covering the outer walls of the fortifications. To eliminate the negative effect, the injection method is widely used. A dense liquid composition is introduced into the formed space, changing the properties of the soil. At the same time, internal surfaces are treated with moisture-retaining substances.