2024年6月8日发(作者：)
Rapid transit (Metro)
The New York City Subway is the world's largest rapid transit system by track lengthand by number
of stations, at 468.
The Moscow Metro is one of the busiest metro systems in the world and is the busiest in Europe.
Rapid transit, also known as metro, subway, underground, or colloquially as "the train", is a
type of high-capacity public transportgenerally found in urban
areas.
[1][2][3]
Unlike buses, trams or light rail, rapid transit systems are electric railways that
operate on an exclusive right-of-way, which cannot be accessed by pedestrians or other vehicles
of any sort,
[4]
and which is often grade separated in tunnelsor on elevated railways.
Modern services on rapid transit systems are provided on designated lines
between stations typically using electric multiple units on rail tracks, although some systems
use guided rubber tyres, magnetic levitation, or monorail. The stations typically have high
platforms, without steps inside the trains, requiring custom-made trains in order to avoid gaps.
They are typically integrated with other public transport and often operated by the same public
transport authorities. However, some rapid transit systems have at-grade intersections between
a rapid transit line and a road or between two rapid transit lines.
[5]
It is unchallenged in its ability
to transport large numbers of people quickly over short distances with little use of land.
Variations of rapid transit include people movers, small-scale light metro, and the commuter
rail hybrid S-Bahn.
The world's first rapid-transit system was the partially underground Metropolitan
Railway which opened as a conventional railway in 1863, and now forms part of the London
Underground.
[6]
In 1868, New York opened the elevated West Side and Yonkers Patent
Railway, initially a cable-hauled line using static steam engines.
The world's largest rapid transit system by both length of track (842 miles (1,355 km),
including non-revenue track)
[7]
and number of stations (468 stations in total)
[8]
is the New York
City Subway. By length of passenger route, the world's longest single-operator rapid transit
system is the Shanghai Metro.
[9][10]
The busiest rapid transit systems in the world by annual
ridership are the Tokyo subway system, the Seoul Metropolitan Subway, the Moscow Metro,
the Beijing Metro, and the Shanghai Metro.
[11]
Terminology
Metro is the most common term for underground rapid transit systems used by non-native
English speakers.
[12]
Rapid transit systems may be named after the medium by which passengers
travel in busy central business districts; the use oftunnels inspires names such
as subway,
[13]
underground,
[14]
Untergrundbahn (U-Bahn) in German,
[15]
or the Tunnelbana (T-
bana) in Swedish;
[16]
the use of viaducts inspires names such
as elevated (el or L), skytrain,
[17]
overhead, oroverground. One of these terms may apply to an
entire system, even if a large part of the network (for example, in outer suburbs) runs at ground
level.
In most of Britain, a subway is a pedestrian underpass; the terms Underground and Tube are
used for the London Underground, and the Tyne and Wear Metro, mostly overground, is known
as the Metro. In Scotland, however, the Glasgow Subway underground rapid transit system is
known as the Subway. Conversely, in the U.S., underground mass transit systems are primarily
known as subways, and the term metro is short for metropolitan area.
History
Initial construction stages of London's Metropolitan Railway atKing's Cross St. Pancras in 1861
The opening in 1863 of London's steam-hauled Metropolitan Railway marked the beginning of
rapid transit. Initial experiences with steam engines, despite ventilation, were unpleasant.
Experiments with pneumatic railways failed in their extended adoption by cities. Electric
traction was more efficient, faster and cleaner than steam and the natural choice for trains
running in tunnels and proved superior for elevated services. In 1890 the City & South London
Railway was the first electric-traction rapid transit railway, which was also fully
underground.
[18]
Both railways were eventually merged into London Underground. The
1893 Liverpool Overhead Railway was designed to use electric traction from the outset.
[19]
The technology quickly spread to other cities in Europe, Canada and the United States with
some railways being converted from steam and others being designed to be electric from the
outset. Budapest in Hungary and Glasgow, Chicago and New York all converted or purpose-
designed and built electric rail services.
[20]
There were 19 systems by 1940, and 66 by
1984.
[citation needed]
Cities such as Osloand Marseille opened extensive systems in the 1960s and
many new systems were introduced in Southeast Asia and Latin America.
[15]
Advancements in technology have allowed new automated services. Hybrid solutions have also
evolved, such as tram-trainand premetro, which incorporate some of the features of rapid transit
systems.
[18]
In response to cost, engineering considerations and topological challenges some
cities have opted to construct tram systems.
[21]
Operation
Rapid transit is used in cities, agglomerations, and metropolitan areas to transport large
numbers of people often short distances at high frequency. The extent of the rapid transit system
varies greatly between cities, with several transport strategies.
Some systems may extend only to the limits of the inner city, or to its inner ring of suburbs with
trains making frequent station stops. The outer suburbs may then be reached by a
separate commuter rail network where more widely spaced stations allow higher speeds. In
some cases the differences between urban rapid transit and suburban systems are not clear.
[3]
Rapid transit systems may be supplemented by other systems such as buses, trams, or commuter
rail. This combination of transit modes serves to offset certain limitations of rapid transit such
as limited stops and long walking distances between outside access points. Bus or tram feeder
systems transport people to rapid transit stops.
[22]
In Toronto, over 50% of its rapid
transit stations have bus and streetcar terminals within the fare-paid zone, providing a
connection without requiring proof of payment.
[citation needed]
Lines
Each rapid transit system consists of one or more lines, or circuits. Each line is serviced by at
least one specific route with trains stopping at all or some of the line's stations. Most systems
operate several routes, and distinguish them by colors, names, numbering, or a combination
thereof. Some lines may share track with each other for a portion of their route or operate solely
on their own right-of-way. Often a line running through the city center forks into two or more
branches in the suburbs, allowing a higher service frequency in the center. This arrangement is
used by many systems, such as the Copenhagen Metro
[23]
and the New York City Subway.
[24]
Alternatively, there may be a single central terminal (often shared with the central railway
station), or multiple interchange stations between lines in the city centre, for instance in
the Prague Metro.
[25]
The London Underground
[26]
and Paris Métro
[27]
are densely built systems
with a matrix of crisscrossing lines throughout the cities. The Chicago 'L' has most of its lines
converging on The Loop, the main business, financial, and cultural area. Some systems have a
circular line around the city center connecting to radially arranged outward lines, such as
the Moscow Metro'sKoltsevaya Line and Tokyo's Yamanote Line.
The capacity of a line is obtained by multiplying the car capacity, the train length, and
the service frequency. Heavy rapid transit trains might have six to twelve cars, while lighter
systems may use four or fewer. Cars have a capacity of 100 to 150 passengers, varying with
the seated to standing ratio—more standing gives higher capacity. Bilevel cars, used mostly on
German S-Bahn type systems, have more space, allowing the higher seated capacity needed on
longer journeys. The minimum time interval between trains is shorter for rapid transit than for
mainline railways owing to the use of block signaling: the minimum headway might be 90
seconds, which might be limited to 120 seconds to allow for recovery from delays. Typical
capacity lines allow 1,200 people per train, giving 36,000 people per hour. The highest attained
capacity is 80,000 people per hour by the MTR Corporation in Hong Kong.
[28]
Network topologies
Rapid transit topologies are determined by a large number of factors, including geographical
barriers, existing or expected travel patterns, construction costs, politics, and historical
constraints. A transit system is expected to cover an area with a set of lines, which consist of
shapes summarized as "I", "U", "S", and "O" shapes or loops. Geographical barriers may cause
chokepoints where transit lines must converge (for example, to cross a body of water), which
are potential congestion sites but also offer an opportunity for transfers between lines. In
Walker's analysis, loops appear to provide good coverage, but are inefficient for everyday
commuting use, while a rough grid pattern offers a wide variety of routes, while still
maintaining reasonable speed and frequency of service.
[29]
Circle, w
Circle-radial,
g, London,Madrid, Moscow,Seoul, Shanghai,Tokyo
Secant,
,Bucharest,Budapest,Hyderabad,Kharkiv, Kiev,Kuala
Lumpur,Munich, Prague,São Paulo,Tashkent,Tehran
Complex grid,
, Delhi, New
York, Shenzhen,Osaka, Paris,Taipei
X-shaped,
dam,Brussels, Oslo,Porto, Rio
de Janeiro, San Francisco,Stockholm
Diameter line,
s, Helsinki,Lima, Mumbai,Sendai,Yekaterinburg
Vesica piscis,
e.g. Cairo,Lille, Milan,Nuremberg,Rotterdam, Sofia(partly), Tyne
and Wear
Cross,
a,Bangalore,Esfahan,Kaohsiung, Kyoto,Minsk,Philadelphia,Rome, Sapporo,Warsaw
Passenger information
Information panel showing the current location and upcoming stops of an East-West Singapore
MRT train. Note that each station has a unique alpha-numeric code, e.g.: EW26 Lakeside
Rapid transit operators have often built up strong brands. The use of a single letter as a station
sign has become widespread, with systems identified by the letters L, M, S, T and U, among
others.
[30]
In the Singapore MRT, each station was assigned a unique alphanumeric symbol. E.g.:
EW26 Lakeside (26th station on the East West Line). Interchange stations will then have at
least two codes. For example, HarbourFront will have two codes, NE1, 1st station on the North
East Line section and CC29, 29th station on the Circle Line section. (NE1/CC29 HarbourFront)
Branding has focused on easy recognition—to allow quick identification even in the vast array
of signage found in large cities—combined with the desire to communicate speed, safety, and
authority.
[31]
In many cities, there is a single corporate image for the entire transit authority, but the rapid
transit uses its own logo that fits into the profile.
A transit map is a topological map or schematic diagram used to show the routes and stations
in a public transport system. The main components are color-coded lines to indicate each line
or service, with named icons to indicate stations. Maps may show only rapid transit or also
include other modes of public transport.
[32]
Transit maps can be found in transit vehicles, on platforms, elsewhere in stations, and in
printed timetables. Maps help users understand the interconnections between different parts of
the system; for example, they show theinterchange stations where passengers can transfer
between lines. Unlike conventional maps, transit maps are usually not geographically accurate,
but emphasize the topological connections among the different stations. The graphic
presentation may use straight lines and fixed angles, and often a fixed minimum distance
between stations, to simplify the display of the transit network. Often this has the effect of
compressing the distance between stations in the outer area of the system, and expanding
distances between those close to the center.
[32]
With widespread use of the Internet and cell phones globally, transit operators now use these
technologies to present information to their users. In addition to online maps and timetables,
some transit operators now offer real-time information which allows passengers to know when
the next vehicle will arrive, and expected travel times. The standardized GTFS data format for
transit information allows many third-party software developers to produce web and
smartphone app programs which give passengers customized updates regarding specific transit
lines and stations of interest.
Safety and security
Platform-edge doors are used for safety at Daan Station on Line 2,Taipei Metro, Taiwan
See also: Classification of railway accidents
Compared to other modes of transport, rapid transit has a good safety record, with few accidents.
Rail transport is subject to strict safety regulations, with requirements for procedure and
maintenance to minimize risk. Head-on collisions are rare due to use of double track, and low
operating speeds reduce the occurrence and severity of rear-end
collisions and derailments. Fire is more of a danger underground, such as the King's Cross
fire in London in November 1987, which killed 31 people. Systems are generally built to allow
evacuation of trains at many places throughout the system.
[33][34]
High platforms (usually over 1 meter / over 3 feet) are a safety risk, as people falling onto the
tracks have trouble climbing back. Platform screen doors are used on some systems to eliminate
this danger.
Rapid transit facilities are public spaces and may suffer from security problems: petty crimes,
such as pickpocketingand baggage theft, and more serious violent crimes. Security measures
include video surveillance, security guards, andconductors. In some countries a transit
police may be established. These security measures are normally integrated with measures to
protect revenue by checking that passengers are not travelling without paying.
[35]
Rapid transit
systems have been subject to terrorism with many casualties, such as the 1995 Tokyo subway
sarin gas attack
[36]
and the 2005 "7/7" terrorist bombings on the London Underground.
Infrastructure
Most rapid transit trains are electric multiple units with lengths from three to over ten
cars.
[37]
Power is commonly delivered by a third rail or by overhead wires. The whole London
Underground network uses fourth rail and others use the linear motor for propulsion.
[38]
Most
run on conventional steel railway tracks, although some use rubber tires, such as the Montreal
Metro and Mexico City Metro and some lines in the Paris Métro. Rubber tires allow steeper
gradients and a softer ride, but have higher maintenance costs and are less energy efficient.
They also lose traction when weather conditions are wet or icy, preventing above-ground use
of the Montréal Metro but not rubber-tired systems in other cities.
[39]
Crew sizes have decreased
throughout history, with some modern systems now running completely unstaffed
trains.
[40]
Other trains continue to have drivers, even if their only role in normal operation is to
open and close the doors of the trains at stations.
Guideway types
Landungsbrücken station in Hamburg is an example where the U-Bahn is on surface while the S-
Bahn station is on lower level
Underground tunnels move traffic away from street level, avoiding delays caused bytraffic
congestion and leaving more land available for buildings and other uses. In areas of high land
prices and dense land use, tunnels may be the only economic route for mass transportation. Cut-
and-cover tunnels are constructed by digging up city streets, which are then rebuilt over the
tunnel; alternatively, tunnel-boring machines can be used to dig deep-bore tunnels that lie
further down in bedrock.
[18]
Street-level railways are used only outside dense areas, since they create a physical barrier that
hinders the flow of people and vehicles across their path. This method of construction is the
cheapest as long as land values are low. It is often used for new systems in areas that are planned
to fill up with buildings after the line is built.
[41]
Surface-level systems may have
dedicated rights-of-way, or may operate by street running in mixed traffic.
Elevated railways are a cheaper and easier way to build an exclusive right-of-way without
digging expensive tunnels or creating barriers. In addition to street level railways they may also
be the only other feasible alternative due to considerations such as a high water table close to
the city surface that raises the cost of, or even precludes underground railways (e.g. Miami).
Elevated guideways were popular around the beginning of the 20th century, but fell out of favor;
they came back into fashion in the last quarter of the century—often in combination with
driverless systems, for instance Vancouver's SkyTrain, London's Docklands Light
Railway,
[42]
the Miami Metrorail, and the Bangkok Skytrain.
[43]
People mover systems are self-contained rapid transit systems serving relatively small areas
such as airports, downtown (central) districts or theme parks, either as independent systems or
as shuttle services feeding other transport systems. They are usually driverless and normally
elevated. Monorails have been built as both conventional rapid transits and as people movers,
either elevated or underground. They are in commercial use in several places, including
Germany, Japan and many international airports.
Light metro is used when the speed of rapid transit is desired, but for smaller passenger numbers.
It often has smaller trains, of typically two to four cars, lower frequency and longer distances
between stations, though it remains grade separated. Light metros are sometimes used
as shuttles feeding into the main rapid transit system.
[44]
Some systems have been built from
scratch, others are former commuter rail or suburban tramway systems that have been upgraded,
and often supplemented with an underground or elevated downtown section.
[16]
Stations
The spacious Getafe Central station on Line 12 of Madrid Metro has several clearly visible levels
Stations function as hubs to allow passengers to board and disembark from trains. They are also
payment checkpoints and allow passengers to transfer between modes of transport, for instance
to buses or other trains. Access is provided via either island- or side platforms.
[45]
Underground
stations, especially deep-level ones, increase the overall transport time: long escalator rides to
the platforms mean that the stations can become bottlenecks if not adequately built. Some
underground stations are integrated into shopping centers, or have underground access to large
nearby commercial buildings.
[46]
In suburbs, there may be a "park and ride" connected to the
station.
[47]
To allow easy access to the trains, the platform height allows step-free access between platform
and train. If the station complies with accessibility standards, it allows both disabled people and
those with wheeled baggage easy access to the trains,
[48]
though if the track is curved there can
be a gap between the train and platform. Some stations use platform screen doors to increase
safety by preventing people falling onto the tracks, as well as reducing ventilation costs.
The deepest station in the world is Arsenalna station in Kiev, Ukraine.
[49]
Particularly in the former Soviet Union and other Eastern European countries, but to an
increasing extent elsewhere, the stations were built with splendid decorations such as marble
walls, polished granite floors and mosaics—thus exposing the public to art in their everyday
life, outside galleries and museums. The systems in Moscow, St.
Petersburg, Tashkent and Kiev are widely regarded as some of the most beautiful in the
world.
[50]
Several other cities such as Stockholm, Montreal, Lisbon, Naples and Los
Angeles have also focused on art, which may range from decorative wall claddings, to large,
flamboyant artistic schemes integrated with station architecture, to displays of ancient artifacts
recovered during station construction.
[51]
It may be possible to profit by attracting more
passengers by spending relatively small amounts on grand architecture,
art, cleanliness, accessibility, lighting and a feeling ofsafety.
[52]
Modal tradeoffs and interconnections
Stratford Station in London is shared by London Undergroundtrains (left) and Greater Angliarail
services (right), as well as the Docklands Light Railway (not shown).
Since the 1980s, trams have incorporated several features of rapid transit: light rail systems
(trams) run on their own rights-of-way, thus avoiding congestion; they remain on the same level
as buses and cars. Some light rail systems have elevated or underground sections. Both new
and upgraded tram systems allow faster speed and higher capacity, and are a cheap alternative
to construction of rapid transit, especially in smaller cities.
[21]
A premetro design means that an underground rapid transit system is built in the city centre,
but only a light rail or tram system in the suburbs. Conversely, other cities have opted to build
a full metro in the suburbs, but run trams in city streets to save the cost of expensive tunnels.
In North America, interurbans were constructed as street-running suburban trams, without the
grade-separation of rapid transit. Premetros also allow a gradual upgrade of existing tramways
to rapid transit, thus spreading the investment costs over time. They are most common in
Germany with the name Stadtbahn.
[37]
Suburban commuter rail is a heavy rail system that operates at a lower frequency than urban
rapid transit, with higher average speeds, often only serving one station in each village and
town. Commuter rails of some cities (such as GermanS-Bahns, Chennai rail, Australian
cityrails, Danish S-tog etc.) widely provide a mass transit within city as urban metro systems.
As opposition, in some cities (such as PATH in New York, Dubai Metro, Los Teques
Metro, Tyne & Wear Metro, MetroSur and other lines of Madrid Metro, Singapore
MRT, Taipei Metro, Kuala Lumpur's RapidKL Light Rail Transitetc.) the mainly urban rapid
transit systems branch out to the nearest suburbs.
Some cities have opted for a hybrid solution, with two tiers of rapid transit: an urban system
(such as the Paris Métro, Berlin U-Bahn, London Underground) and a suburban system (such
as their counterparts RER, S-Bahn, futureCrossrail, respectively). The suburban systems run on
their own tracks with generally high frequency (though less frequently than the urban system),
and sometimes operated by the national railways. In some cities the national railway runs
through tunnels in the city centre; sometimes commuter trains have direct transfer to the rapid
transit system, on the same or adjoining platforms.
[53][54]
California's BART system functions as
a hybrid of the two: in the suburbs, it functions like a commuter rail, with longer trains, longer
intervals, and longer distance between stations; in downtownSan Francisco, many lines join
and intervals drop to normal subway levels, and stations become closer together. Also, some
other urban or "near urban" rapid transit systems (Guangfo Metro, East Rail Line in Hong
Kong, Seoul Subway Line 1, etc.) serves the bi- and multi-nucleus agglomerations.
Costs, benefits, and impacts
The Docklands Light Railway in London allows for dense land use, while retaining a high capacity
As of May 2012, 184 cities have built rapid transit systems.
[55]
The capital cost is high, as is the
risk of cost overrun and benefit shortfall; public financing is normally required. Rapid transit is
sometimes seen as an alternative to an extensive road transport system with
many motorways;
[56]
the rapid transit system allows higher capacity with less land use, less
environmental impact, and a lower cost.
[57]
Elevated or underground systems in city centers allow the transport of people without
occupying expensive land, and permit the city to develop compactly without physical
barriers. Motorways often depress nearby residential land values, but proximity to a rapid
transit station often triggers commercial and residential growth, with large transit oriented
development office and housing blocks being constructed.
[56][58]
Also, an efficient transit system
can decrease the economicwelfare loss caused by the increase of population density in a
metropolis.
[59]
Rapid transit systems have high fixed costs. Most systems are publicly owned, by either local
governments, transit authorities or national governments. Capital investments are often
partially or completely financed by taxation, rather than by passenger fares, but must often
compete with funding for roads. The transit systems may be operated by the owner or by a
private company through a public service obligation. The owners of the systems often also own
the connecting bus or rail systems, or are members of the local transport association, allowing
for free transfers between modes. Almost all transit systems operate at a deficit, requiring fare
revenue, advertising and subsidies to cover costs.
The farebox recovery ratio, a ratio of ticket income to operating costs, is often used to assess
operational profitability, with some systems including Hong Kong's MTR
Corporation,
[60]
and Taipei
[61]
achieving recovery ratios of well over 100%. This ignores both
heavy capital costs incurred in building the system, which are often subsidized withsoft
loans
[62]
and whose servicing is excluded from calculations of profitability, as well as ancillary
revenue such as income from real estate portfolios.
[60]
Some metros, including Hong Kong, are
even financed by the sale of land whose value has been increased by the building of the
system,
[41]
a process known as value capture.
Environmental impacts
The Delhi Metro has won awards for environmentally friendly practices from organisations
including the United Nations,
[63]
RINA,
[64]
and the International Organization for
Standardization,
[64]
becoming the second metro in the world, after the New York City Subway,
to be ISO 14001 certified for environmentally friendly construction.
[65]
It is also the first
railway project in the world to earn carbon credits after being registered with the United
Nations under the Clean Development Mechanism,
[66]
and has so far earned more than 400,000
carbon credits by saving energy through the use of regenerative braking systems on its
trains.
[67]
In order to reduce its dependence on non-renewable sources of energy, Delhi Metro
Rail Corporation is looking forward to harness solar energy and install solar panels in some of
its metro stations.
[68]
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