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subway:see rapid transitrapid transit,
transportation system designed to allow passenger travel within or throughout an urban area, usually employing surface, elevated, or underground railway systems or some combination of these.
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an urban underground or elevated railroad for highspeed mass passenger transit. In the USSR and many other countries it is called the metropolitan (in Russian, metropoliten)\ other designations include “underground” (British), Untergrundbahn (German), and metropolitan (French).
General information. A subway is distinguished by its great throughput capacity and frequency of service and by the high operating speed of the trains. Subways may be built underground (in tunnels), at the ground level, or above ground (on viaducts). Underground lines are the most common, since they do not interfere with the historically developed layout of a city, do not contribute to the congestion of urban surface transportation and pedestrian traffic, and reduce the exposure of buildings to noise and vibration caused by trains. The surface lines of a subway system are usually constructed in areas of a city where building density is relatively low, where an existing subway system is being expanded, or where a common transfer station for the subway system and a suburban railroad is being built, as well as on terminal sections adjacent to the yards. The surface sections of a subway must be protected by barriers. Certain segments may be elevated, depending on the local terrain, but mostly at the crossings of highways, railroads, and water obstacles. A subway system is a necessity in many cities with a population of one million or more, since it is a high-speed transit system that does not contribute to the congestion of city streets and does not have the problem of grade crossings.
A subway system consists of a complex of structures and equipment. Its main components include stations and entrance areas, service areas, escalators, open-line tunnels, side tracks, culs-de-sac, car yards with maintenance workshops, locker rooms, showers and toilets, traction and step-down power substations, and tunnel structures for engineering and sanitation equipment and for ventilation, drainage, and water supply.
Historical survey. The first subway, for steam trains in shallow tunnels, was built in London in 1860–63 by the Metropolitan Railway Company. It was 3.6 km long. In 1890, construction began on deep tunnels in London, and the introduction of electric traction freed the tunnels from smoke and soot and improved the operating conditions of the urban underground lines. An elevated subway (on metal trestles) with cable traction began operation in New York in 1868; cable traction was replaced by steam in 1871 and by electric traction in 1890.
The oldest subways on the continent of Europe are those of Budapest (1896) and Paris (the opening of the first line of the Paris subway was arranged to coincide with the opening of the World Industrial Exhibition in Paris in 1900). Subways were later built in Madrid, Barcelona, Athens, Tokyo, Oslo, and Stockholm. Subway lines were often designed, constructed, and operated by competing firms; as a result, in a number of cases the lines did not constitute a unified system, sometimes differing in gauge and power system voltage.
The development and modernization of existing subway systems and the construction of new systems became particularly important for the larger cities of various countries after World War II. The intensive development of the cities often necessitated elimination of trestle structures and gradual replacement
|Table 1. Subway systems of some cities (as of Jan. 1, 1973)|
|Year service began||Length of lines(km)||Number of stations||Annual passenger traffic|
|New York||1868||385||477||1 ,227,800,000|
|German Democratic Republic|
|Federal Republic of Germany|
of surface and elevated lines by underground lines. (Basic data on the subways of the world’s largest cities, based on information from the International Union of Public Transport, are given in Table 1.)
The development of subway construction in the USSR was begun by the resolution On the Construction of a Subway in Moscow, adopted by the plenum of the Central Committee of the ACP(B) on June 15, 1931. The large construction organization Metrostroi, which was equipped with Soviet machinery, was created to implement the project. Construction of the subway began in 1932. The first lines of the V. I. Lenin Moscow Metro (total length, 11.6 km), with 13 stations and all associated structures, were built in three years, and operation began on May 15, 1935. Such rapid construction progress was unknown in world practice. The construction of the Moscow Metro is continuing; it was not suspended even during the Great Patriotic War (1941–45). The operational length of the Moscow Metro (1973) was more than 148 km (double-track), the constructed length is 156 km, and there are 96 stations. The daily flow of passengers reaches 4.84 million, or 35.7 percent of the total urban passenger traffic. The Moscow Metro is markedly superior to the subways of other countries in terms of the quality of structures, impressiveness of architecture, technical equipment, operational characteristics, and comfort. In accordance with the General Plan for the Development of Moscow adopted by the Central Committee of the CPSU and the Council of Ministers of the USSR in 1971, covering the next 25–30 years, the total length of the Moscow Metro system is to reach 320 km.
The experience gained in building the Moscow Metro was used for construction of subways in other cities of the USSR. On Nov. 15, 1955, the first line of the Leningrad Metro was put into operation; it had eight stations and was 10.8 km long. The first line of the Kiev Metro was opened on Nov. 6, 1960; the Tbilisi Metro, in January 1966; and the Baku Metro, in 1967. Construction of subways has begun in Kharkov and Tashkent; the feasibility of building subways in a number of other cities is being studied.
Planning. The increasing scope of industrial and civil construction in the USSR, the expansion of city limits, the growth of group systems of settlement, and the organization of areas for mass recreation require scientific planning for the integrated expansion of all types of urban transportation, above all subway systems, since they are the most convenient means of mass passenger transit. The main trends in the development of a subway system, including the location of stations and transfer points from line to line and from subway to railroad and other surface transportation, are planned in accordance with the general plan for city development and the plan for the general layout of the subway system. The latter is developed with consideration for the locations of areas of mass employment and of service and recreational establishments, the direction and magnitude of passenger flows, and the necessary interconnections with other kinds of urban, suburban, and intercity passenger transportation.
Subway systems may be designed for independent (closed) movement of trains along separate, noninterconnected lines (for example, in Moscow and Leningrad), for operation with transfer of some trains from one line to another (London and New York), or as combined systems.
The subway is convenient for passengers traveling relatively long distances; therefore, in the USSR the distance between stations is usually 1–2 km. In Berlin, Madrid, Milan, Buenos Aires, Toronto, and some other cities in Europe and America, the average distance is 500–800 m. In a number of cities (for example, Paris, San Francisco, and Los Angeles), high-speed subway lines are planned or under construction. In New York, high-speed (express) trains are operated along routes where express stops are located 3–6 km apart; the express stations are connected to the local line by convenient, short passages (for example, across the platform). Construction of high-speed subways is also planned in the USSR (for Moscow and Leningrad) as a means of reducing travel time.
The depth of subway lines, the type of tunnel structure, and the methods of construction are determined from detailed studies in city planning, geological engineering, and industrial economics. Shallow subway lines are the most economical in terms of construction; in addition, shallow lines can be operated more conveniently and cheaply than deep lines. Passengers spend a minimum amount of time in reaching the trains and leaving the stations. The tunnels of shallow lines are usually 10–15 m below ground level. Deep subways (30–50 m below ground level) are built predominantly in areas of a city with many high-rise buildings, high building density, and a developed underground utility system, and also where geological and hydrogeological conditions are unfavorable for shallow subways. Deep tunnels can be driven with almost no interference with the normal life of a city and have virtually no effect on the stability of buildings and underground utilities.
In modern subways, the standardized route parameters in plan and profile provide excellent operational qualities of the track and smoothness of train travel. The layout of subway lines is determined by the location of areas with high passenger concentrations, by considerations of city planning, and by the presence of underground transportation facilities and utilities (motor-vehicle tunnels, sewer mains, and so on). Shallow tunnels are usually built along the main traffic arteries of a city. In the USSR the minimum permissible radius for curves on main subway lines is 500 m, which is considerably greater than the corresponding figures for foreign subways (London, 100 m; Madrid, 90 m; Berlin, 75 m).
The operational requirements of the rolling stock, and also the necessity of providing drainage, are taken into account in designing the longitudinal profile of a subway line. The maximum permissible track gradient is 0.040 percent; the minimum, 0.003 percent. Stations are located on straight sections and are higher than the rest of the line. The gauge of Soviet subways is the same as the standard railroad gauge (1,520 mm). The most common gauge in foreign subways is 1,435 mm. However, some countries lack a standard track gauge: in Japan there are gauges of 1,067, 1,372, 1,435, and 2,180 mm. Some subway lines in Paris, Montreal, Mexico City, and Sapporo have special track with concrete roadbeds for trains equipped with pneumatic tires. Such a design provides smooth, noiseless train travel and makes possible the use of routes with increased gradients.
Stations. Stations, entrance areas, and transfer junctions, which are directly associated with the handling of passengers, occupy a special place in the complex of structures of a subway. In addition to performing their main function, they also must provide for passenger safety, convenience (such as the shortest possible path from the surface to platform areas and back), and purity and optimum temperature of the air. Transfer stations (junctions) are constructed at locations where various lines intersect or join. Their platform areas are connected by corridors and stairways (corridor junctions) or only by stairways or escalators (two-tier, or tower-type, junctions). Sometimes two lines are located on the same level, with a transfer by crossing the platform, directly from car to car (integrated junctions).
In the USSR, subway stations are equipped with escalators for conveying passengers upward if the height is greater than 5 m. If the height difference is greater than 7 m, escalators for downward conveyance are also provided. Some foreign subways have elevators, with capacities of up to 130 persons.
Shallow stations are usually built by means of cut-and-cover excavation. Their roofing is supported by post-and-beam structures with one, two, or several rows of supports or by vaulted structures. Such structures are designed to support an earth mass 1.0–2.5 m thick, as well as the surface traffic. Deep stations are usually a combination of two, three, or several tunnels, with cast or prefabricated tunnel casings that are sufficiently strong to withstand the pressure of the rock and soil above the tunnel. The lining of each tunnel consists of a series of rings, made of cast-iron or reinforced-concrete tubing. Among such stations, a distinction is made between pier and column stations. In stations of the pier type, the enclosure is supported by massive piers formed by two, four, or more rings of lining. In column-type stations, steel or reinforced-concrete columns are used as the supports. Column-type stations are more complex and more expensive to build than pier stations. However, the interior space is more open in column stations, which makes them more convenient for handling large flows of passengers and provides better visual orientation. In outlying urban areas, where most surface lines are located, stations are built in the form of pavilions or open platforms protected by light canopies.
The type of station also depends to a great extent on the specific construction conditions of the site, particularly the hydrogeological conditions. The first stations of the London Underground were built under the traffic lanes of public streets; they had vaulted brick ceilings and ventilation gratings located in the sidewalks. The tracks were arranged along the central longitudinal axis of the station. Two passenger platforms were located at the outer sides of the tracks. This type of station, with narrow side platforms (1.5–3.0 m), which is of simple construction but is somewhat inconvenient for passengers, has been widely used in subways in Western Europe and America. During subsequent construction of deep stations and open-line tunnels of the London Underground, arched structures made from curved cast-iron sections faced with ceramic tiles were used for the enclosure. Most of the stations of the Paris Metro are of a similar design, spanned by a single stone vault faced with glazed tile; the tracks are in the center, and the passenger platforms are at the edges of the station. After the first stations of the Berlin U-bahn were built, stations with passenger platforms of the island type (with the platform located between the tracks) became popular. Among the advantages of such stations are convenient location of entrances and exits at the ends of the platform, more efficient use of the platform area, ease of passenger orientation, and the feasibility of changing the direction of travel without crossing the tracks.
The construction of foreign subways has generally been dominated by a utilitarian approach to architectural treatment. Rare exceptions to this rule are some entrances to stations in Paris (metal and glass, c. 1900, architect G. Guimard; art nouveau style); the street-level entrance hall of the Arnos Grove station in London (brick and concrete, 1932; architects P. Adams and others). Only since the 1950’s has more attention been devoted to the appearance of subways, particularly the stations. The most modern designs, as well as novel structural and ornamental materials and advertising and informational displays, are being used (stations of the east-west line in Budapest, the first stage of which was completed in 1970, and the north-south line in Munich, 1965–71).
In the USSR, from the very beginning of subway construction, the stations were designed as extensive architectural complexes of great social importance. Among the prominent Soviet architects who took part in designing stations of the Moscow Metro were V. G. Ge’freikh, I. A. Fomin, and A. V. Shchusev, who strove not only to create a comfortable environment for the passenger and to overcome the depressing visual impression of a dungeon but also to create an individual architectural appearance for each station. Subway architecture reflects several stages in the general development of Soviet architecture. Many architects used forms and decorative treatments borrowed from classical architecture (for example, the architectural treatment of the deep pier-type Krasnye Vorota [now Lermontovskaia] station, 1935; architect I. A. Fomin, engineer A. F. Denishchenko). The innovative architectural treatment of a number of other stations stems from the artistic expressiveness of the structure itself—for example, the shallow column-type Dvorets Sovetov (now Kropotkinskaia) station (1935; architects A. N. Dushkin and la. G. Likhtenberg, engineer L. V. Boretskii), where the uniquely designed artificial lighting that reveals the structure of the ceiling became one of the fundamental means of architectural expression. In the deep column-type Maiakovskaia station (1938–39; architect A. N. Dushkin, engineer R. A. Sheinfain), the originality and novelty of the complex ceiling structure, which led to freedom of its spatial composition, is emphasized by the use of corrugated stainless steel in the decoration of columns and arches. Entrances have been constructed in existing or newly erected buildings or in separate street-level structures (the entrance to the Krasnye Vorota [now Lermontovskaia] station, 1935; architect N. A. Ladovskii).
From the late 1930’s to the early 1950’s the architectural treatment and designs of subway stations were usually associated with a particular theme. For example, the design theme for the Izmailovskaia (now Izmailovskii Park) station (1944; architect B. S. Vilenskii) and the Komsomo’skaia-Ko’tsevaia station, (1952; architect A. V. Shchusev and others) was Russia’s military glory of the past and the heroic deeds of the Soviet people during the Great Patriotic War (1941–5). The decorative street-level entrances use mosaics, paintings, sculptures, and applied art (works of N. la. Dan’ko, A. A. Deineka, P. D. Korin, M. G. Manizer, and others).
Since the late 1950’s, construction of subway stations has been standardized with regard to spatial planning and industrially manufactured structural components; this made possible acceleration of construction work and a decrease in construction costs. The shallow stations of the Kaluzhskaia radial line of the Moscow Metro (1962; architects S. M. Kravets, G. E. Golubev, and M. F. Markovskii) have been duplicated in other radial lines. The appearance of each station is made individual by using a variety of materials of different colors and textures and by differences in lighting systems. New types of subway stations were built—for example, the Leninskie Gory station in Moscow (1959; engineers V. G. Andreev and N. N. Rudomazin; architects K. N. lakovlev and A. I. Susorov), which is located above the Moskva River and the traffic lanes of the embankment, on the lower level of a double-decker bridge, and the Park Pobedy station in Leningrad (1961; architect A. K. Andreev; engineers L. V. Frolov, G. A. Skobennikov, and S. P. Shchukin), which is the world’s first station without side platform areas; the passengers enter the trains directly from the central hall, through automatic doors (such a design considerably decreases the volume and cost of construction). Street-level entrances are usually built from prefabricated reinforced-concrete elements; they are constructed as light, functionally designed halls with large glass areas.
Since the late 1950’s, world urban planning practice has exhibited a tendency to combine subway stations with other structures of urban transportation facilities. Such consolidation is intended to provide greater convenience and increased safety for passengers and more efficient use of the underground areas of cities. Combined stations are being built to provide convenient transfer between subways and urban and suburban railroads. Some stations abroad also connect surface transportation (buses or streetcars) to the subways; special high-speed (express) stations and local stations are also being built. Branch systems of entrances and exits are provided at the stations and are sometimes combined with underpasses below streets and squares. Shopping facilities, ticket offices, and other amenities are sometimes also provided.
Construction. Construction of a subway line begins with surveys to reproduce the planned route in the field. Correct orientation of tunnels driven by the tunneling method of excavation is achieved by transmitting the planned coordinates through the shaft heads. For deep subways the shafts are usually located to the side of the route and are connected to the tunnel by access galleries. During the construction period the galleries are used for access; after completion of construction, they are occupied by ventilation equipment. In driving shallow tunnels, the use of the tunneling method requires special measures to prevent surface settling or damage to nearby underground utility equipment or buildings. In the cut-and-cover method of construction, the surface of the street is removed, a trench is excavated using pilings or sheeting to prevent the sides from collapsing, the tunnel structures are built in the excavation, and the trench is filled and the street replaced. Surface traffic is detoured around the site or is carried over the trench on temporary decking. Underground utilities are relocated in advance or are suspended from the trench reinforcements. Supports and foundations of the buildings located adjacent to the route are reinforced if necessary.
In the tunneling method, tunnels are driven by a heading machine or by using mining techniques. Special techniques, such as caissons, soil freezing, water drawdown, or chemical soil packing, are used under difficult engineering and geological conditions (quicksand or water-bearing soils). The tunnel structures of subways may be built from prefabricated reinforced-concrete or metal components or from cast or reinforced concrete.
Construction of subways is usually accomplished using industrial methods, with integrated mechanization of all basic processes. Among the important achievements of Soviet subway construction technology are the development of prefabricated reinforced-concrete tunnel casings and a method for constructing tunnels using cast compressed concrete, which significantly reduces metal consumption and construction costs, and also the development of mechanized heading machines, block layers, rock-loading machines, and self-erecting cranes. To protect station structures from seepage of subterranean water, a system of water-draining canopies made of asbestos cement or other materials is used in addition to waterproofing.
The Moscow Metro is being built under difficult engineering and geological conditions. Tunnels are driven through various rock and soil stratifications (weak soils and quicksand, deposits partially destroyed by ancient rivers, and mixtures of strong and fissured rock). In driving several tunnels it was necessary to overcome considerable rock pressure and a copious influx of subterranean water (up to 2,500 cu m per hr in some sections). Several tunnels were driven under the Moskva River. The builders of the Moscow Metro developed and made wide use of a method for building shallow tunnels under various geological conditions and with integrated mechanization of operations, without breaking the surface of the ground. In the construction of the Kaluzhskaia radial line using this method, the rate of driving tunnels with reinforced-concrete casings reached 14.9 m per day. During the construction of the Zhdanovskaia radial line in unstable sands, a heading machine with horizontal sectioning platforms was used; it made possible safe driving of the tunnel at a rate of 400 m per month without reinforcement of the face. In the Zamoskvoretskii radial line the rate reached 430.6 m per month—an outstanding achievement in worldwide subway construction practice.
Construction of the Leningrad Metro is also characterized by the high level of mechanization of tunnel-driving operations. The rate of construction of open-line tunnels with reinforced-concrete lining has been as high as 308 m per month. Tunnels have been driven under the Neva River.
The Kiev Metro is being built under difficult engineering and geological conditions, which require special production methods and new mechanized equipment. Open-line tunnels are driven through soft, unstable soil by means of a mechanized heading machine whose working member (in the shape of a chuck) is equipped with knife cutters. The deep Politekhnicheskii Institut station is the world’s first station to be constructed entirely from prefabricated reinforced concrete. A valuable contribution to the development of subway construction technology was made by the builders of the subways in Tbilisi and Baku.
Equipment, traffic control, and rolling stock.. The design of subway tracks and their foundations, welding of rail joints, and fastening of rails to elastic pads assure excellent operational properties of the track and smooth travel of trains, even at high speeds. Switching is controlled from central points. In some foreign subways the tracks are laid on crushed-stone ballast, which causes the tunnels to become dirty and leads to the formation of dust during the passage of trains.
The power-supply system of a subway includes traction and step-down substations. In traction substations, high-voltage alternating current (6–10 kilovolts [kV]) is converted to direct current at 825 V. The current then passes through a cable to the contact rails and then through slide collectors to the traction motors of the train. Step-down substations provide power for lighting and for driving escalators, ventilators, pumps, and other equipment. The substations are automated and remotely controlled from a central dispatcher’s post. Safety of train travel (at speeds in excess of 90 km/hr in some sections), with separations of 90 sec to 2 min, is ensured by a centralized system of signals, interlocking, and automatic control, which automatically stops a train that has passed a red signal and includes automatic locomotive signaling. Automatic control of trains is becoming increasingly widespread in subways.
Subways are equipped with suction-and-exhaust ventilation systems, which provide the air exchange required for normal health conditions for passengers and service personnel. Clean air enters the tunnels and stations through trunk shafts or the lower compartments of escalator tunnels, where powerful blowers are located. To improve temperature conditions, in winter all the ventilation equipment of a station operates in the exhaust mode and all the tunnel equipment operates in the fresh-air supply mode; in summer the arrangement is reversed. Some foreign subways have only natural ventilation and rely on the piston effect of the trains; however, in practice this arrangement fails to produce a satisfactory microclimate.
Soviet subway cars are spacious and convenient for entry, exit, and travel. Their capacity is 270 persons, and there are 44 seats. Continuous improvements in the design of rolling stock have made possible an increase in operating speeds, the introduction of electric braking, and a reduction in weight without sacrificing seating capacity (current car models weigh 18 percent less than older models, and their consumption of electric power is 20–22 percent lower).
Among the leading trends in the development of Soviet subways are an increase in grid density (to approximately 0.3 km/km2), the design of a branch system of entrances near centers of heavy use, and the provision of convenient transfer stations.
The builders of the Soviet subways are rendering assistance in the design and construction of subways in many countries of the world, including those in the capitals of the socialist countries of Europe (Budapest, Warsaw, Prague, and Sofia).
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G. E. GOLUBEV and I. M. IAKOBSON
What does it mean when you dream about the subway?
As a way to travel to one’s destination underground, a subway may symbolize the dreamer’s reaching a goal through unconscious methods.