London Underground

The London Underground is a rapid transit system that serves a large part of Greater London and some neighbouring areas of Essex, Hertfordshire and Buckinghamshire. It is the world's oldest underground railway system. Services began on 10 January 1863 on the Metropolitan Railway; most of the initial route is now part of the Hammersmith & City line. Despite its name, about 55% of the network is above ground. Popular local names include the Underground and, more colloquially, the Tube, in reference to the tubular cylindrical shape of the system's deep-bore tunnels.
The numerous railways which make up the modern London Underground network, most of which were built by rival companies, were integrated into one system for the first time in 1933 with the creation of the London Passenger Transport Board (LPTB) - more commonly known by its shortened name: "London Transport" (LT). The network became a single entity when London Underground Limited (LUL) was formed in 1985.http://www.tfl.gov.uk/corporate/modesoftransport/londonunderground/1604.aspx Since 2003, LUL has been administered as a wholly owned subsidiary of Transport for London (TfL) — the statutory corporation responsible for most aspects of the transport system throughout Greater London — which is run by a board appointed by and chaired by the Mayor of London.TFL London Underground history|http://www.london.gov.uk/help/faq.jsp#transport
The Underground has 268 stations and runs over 253 miles (400 km) of trackAccording to "", the total route length is 253 mi or 408 km. But in July 2007 the same page showed the same route length even though there were more stations. Thus it must not have been fully updated for the closure of the East London line, whose route length was about 7 km., making it the longest underground railway in the world by route length, and one of the most served in terms of stations.
There are also numerous closed stations. In 2007 over one billion passenger journeys were recorded, amounting to the carrying of 28 million individual passengers every year. As of March 2007, an average of just over 3 million people use the Underground each day, with an average of 3.4 million passengers on weekdays.
==History==
The first railways to be built in the United Kingdom were constructed in the early 19th century. By 1850 there were 7 separate railway termini located in the London area: London Bridge, Euston, Paddington, King's Cross, Shoreditch, Waterloo and Fenchurch Street. Only Fenchurch Street was located within the City of London itself. London had also seen a large increase in road traffic congestion in this period. This was due in part to the fact that most people travelling to London by rail had to complete their jouneys into the city centre by cab or omnibus. The concept of an underground railway linking the City of London with the mainline termini had first been proposed in the 1830s. But it was not until the 1850s that this idea was taken seriously as a solution to traffic congestion problems.The London Underground - An illustrated history, Oliver Green, pp.3-4 (Ian Allen Ltd., 1987)
In 1854 an Act of Parliament was passed approving the construction of an underground railway between Paddington Station and Farringdon Street via King's Cross, which was to be called the Metropolitan Railway. This was to be built with the support of the Great Western Railway, who helped fund the project on the grounds that a junction would be built with their mainline terminus at Paddington. However construction did not begin until February 1860 due to financial problems. The fact that this project got underway at all was largely due to the lobbying of Charles Pearson, who was Solicitor to the City of London at the time. In 1859 he finally persuaded the City of London Corporation to help fund the scheme.
The Metropolitan Railway was opened to the public on 10 January 1863. It was the world's first urban underground passenger-carrying railway. Within a few months of opening it was carrying over 26,000 passengers a day.The London Underground - An illustrated history, Oliver Green, p.5 (Ian Allen Ltd., 1987) A year later the railway was extended to Hammersmith in the west and a year after that it was extended to Moorgate in the east. Most of this original route is now part of the Hammersmith and City Line.
Other lines swiftly followed, and by 1884 the Inner Circle (today's Circle line) was completed as a joint venture between the Metropolitan Railway and its rival the Metropolitan District Railway.
The first trains were steam-hauled, which required effective ventilation to the surface. Ventilation shafts at various points on the route allowed the engines to expel steam and bring fresh air into the tunnels. One such vent is at Leinster Gardens, W2.
 In order to preserve the visual characteristics in what is still a well-to-do street, a five-foot-thick (1.5 m) concrete façade was constructed to resemble a genuine house frontage.
The early tunnels were dug using cut-and-cover construction methods. This caused widespread disruption and required the demolition of several properties on the surface. Following advances in the use of tunnelling shields, electric traction and deep-level tunnel designs, later railways were built even further underground. This caused far less disruption at ground level than the cut-and-cover construction method did. It was therefore cheaper and preferable. The City & South London Railway (now part of the Northern line) opened in 1890. It was the first "deep-level", electrically operated, route.
By the end of the 19th century, the Metropolitan Railway company had extended its lines far outside of London, creating new suburbs in the process. From the 1870s, right up until the 1930s, the company pursued ambitions to maintain the railway as a main-line operation rather than a rapid transit service. 
===Into the 20th century===
In the early 20th century, the presence of six independent operators running different Underground lines caused passengers substantial inconvenience; in many places passengers had to walk some distance above ground to change between lines. The costs associated with running such a system were also heavy, and as a result many companies looked to financiers who could give them the money they needed to expand into the lucrative suburbs as well as electrify the earlier steam operated lines. The most prominent of these was Charles Yerkes, an American tycoon who between 1900 and 1902 acquired the Metropolitan District Railway and the as yet unbuilt Charing Cross, Euston & Hampstead Railway (later to become part of the Northern line). 
Yerkes also acquired the Brompton & Piccadilly Circus Railway (jointly to become the Great Northern, Piccadilly & Brompton Railway, the core of the modern Piccadilly line) and the Baker Street & Waterloo Railway (to become the Bakerloo line) to form Underground Electric Railways of London Company Ltd (UERL) on 9 April 1902. That company also owned three tramway companies and went on to buy the London General Omnibus Company, creating an organisation colloquially known as "the Combine". 
In early 1908 the underground railway operators agreed to promote their services jointly as "the Underground", creating a free publicity map of the network in the process. New station signs and ticketing arrangements were also put into place. 
On 1 January 1913 the UERL absorbed two other independent tube lines, the City & South London Railway (now part of the Northern Line) and the Central London Railway (now known as the Central Line), the latter having opened an important east-west cross-city line from Bank to Shepherd's Bush on 30 July 1900. The Central London Railway was nicknamed the "Twopenny Tube" for its flat fare and cylindrical tunnels; the "tube" nickname was eventually transferred to the Underground system as a whole. 
As the monopoly of the Combine asserted itself, only the Metropolitan Railway stayed away from this process of integration, retaining pretensions of being considered to be a main-line railway. Proposals were put forward for a merger between the two companies in 1913 but the plan was rejected by the Metropolitan. The only remaining independent underground railway in London, the Great Northern and City Railway (which ran a service between Moorgate and Finsbury Park), was acquired by the Metropolitan in the same year.
===The 1930s and 1940s===
In 1933 the Combine, the Metropolitan Railway and all the municipal and independent bus and tram undertakings were merged into the London Passenger Transport Board (LPTB), a self-supporting and unsubsidised public corporation which came into being on 1 July 1933. The LPTB soon became more widely known as "London Transport" (LT), its shortened title.
London Transport set in motion a scheme for the expansion of the network, the 1935–1940 New Works Programme. This consisted of plans to extend some lines, to take over the operation of others from the main-line railway companies, and to electrify the entire network. During the 1930s and 1940s, several sections of main-line railway were converted into (surface) lines of the Underground. The oldest part of today's Underground network is the Central line between Leyton and Loughton, which opened as a railway seven years before the Underground itself.
The outbreak of World War II delayed all these schemes. From mid-1940, the Blitz led to the use of many underground stations as shelters during air raids and overnight. The authorities initially tried to prevent this, but later supplied bunks, latrines, and catering facilities. Later in the war, eight London deep-level shelters were constructed under stations, ostensibly to be used as shelters (each deep-level shelter could hold 8,000 people) though plans were in place to convert them for a new express line parallel to the Northern Line after the war. Some stations (now mostly disused) were converted into government offices: for example, Down Street was used for the headquarters of the Railway Executive Committee and was also used for meetings of the War Cabinet before the Cabinet War Rooms were completed;
 Brompton Road was used as a control room for anti-aircraft guns and the remains of the surface building are still used by London's University Royal Naval Unit (URNU) and University London Air Squadron (ULAS).
===Post-war developments===
On 1 January 1948 London Transport was nationalised by the incumbent Labour government and incorporated into the operations of the British Transport Commission (BTC). The LTPB was renamed the "London Transport Executive". 
The BTC prioritised the reconstruction of its main-line railways, which had also been nationalised, over the maintenance of the Underground. Although it committed itself to the completion of the New Works programme, many of the original plans were shelved. However the BTC did authorise the completion of the electrification of the network, seeking to replace steam locomotives on the parts of the system where they still operated. This phase of the programme was completed when the Metropolitan Line was electrified to Chesham in 1960. Steam locomotives were fully withdrawn from London Underground passenger services on 9th September 1961 - when British Railways took over the operations of the Metropolitan Line between Amersham and Aylesbury. 
In 1963 the London Transport Executive was replaced by the London Transport Board, directly accountable to the Ministry of Transport. On 1st January 1970, the Greater London Council (GLC) took over responsibility for London Transport. 
The first real post-war investment in the network came with the carefully planned Victoria line on a diagonal northeast-southwest alignment beneath central London, incorporating centralised signalling control and automatically driven trains which opened in stages between 1968 and 1971. The Piccadilly line was extended to Heathrow Airport in 1977, and the Jubilee line was opened in 1979, taking over part of the Bakerloo line, with new tunnels between Baker Street and Charing Cross. 
In 1984, Margaret Thatcher's Conservative government removed London Transport from the GLC's control, replacing it with London Regional Transport (LRT) - a statutory corporation for which the Secretary of State for Transport was directly responsible. The government planned to modernise the system whilst slashing its subsidy from taxpayers and ratepayers at the same time. As part of this strategy London Underground Limited was set up in 1985, as a wholly owned subsidiary of LRT, to run the network on LRT's behalf. This period saw the introduction of automatic ticketing machines and network-wide Travelcards. In 1994, with the privatization of British Rail, LRT took control of the Waterloo and City Line, incorporating it fully into the Underground network for the first time. In 1999 the Jubilee Line extension to Stratford in London's East End was begun. This plan included the opening of a completely refurbished interchange station at Westminster. The Jubilee's old terminal platforms at Charing Cross were abandoned but maintained operable for emergencies.
===Into the 21st century===
Transport for London (TfL) replaced LRT in 2000, a development that coincided with the creation of a directly elected Mayor of London and the Greater London Assembly. 
In January 2003 the Underground began operating as a Public–Private Partnership (PPP), whereby the infrastructure and rolling stock were maintained by two private companies (Metronet and Tube Lines) under 30-year contracts, whilst London Underground Limited remained publicly owned and operated by TfL.
There was much controversy over the implementation of the PPP. Supporters of the change claimed that the private sector would eliminate the inefficiencies of public sector enterprises and take on the risks associated with running the network, while opponents said that the need to make profits would reduce the investment and public service aspects of the Underground. There has since been criticism of the performance of the private companies; for example the January 2007 edition of The Londoner,
 a newsletter published periodically by the Greater London Authority, listed Metronet's mistakes of 2006 under the headline Metronet guilty of 'inexcusable failures'. 
Metronet was placed into administration on 18 July 2007.
http://www.metronetrail.com/default.asp?sID=1184745625515 TfL has taken over Metronet's outstanding commitments. 
The UK government has made concerted efforts to find another private firm to fill the vacuum left by the liquidation of Metronet. However only TfL has expressed a viable interest in taking over Metronet's responsibilities so far. Even though Tube Lines appears to be stable, this has put the long-term future of the PPP scheme in doubt. The case for PPP was also weakened in 2008 when it was revealed that the demise of Metronet had cost the UK government £2bn. The five private companies that made up the Metronet alliance had to pay £70m each towards paying off the debts acquired by the consortium. But due to a deal struck with the government in 2003, when the PPP scheme began operating, the companies were protected from any further liability. The UK taxpayer therefore had to foot the rest of the bill. This undermined the argument that the PPP would place the risks involved in running the network into the hands of the private sector.Railway Magazine, April 2008 issue, p.6
==Transport for London==
Transport for London (TfL) was created in 2000 as the integrated body responsible for London's transport system. It is part of the Greater London Authority and is constituted as a statutory corporation regulated under local government finance rules.http://www.tfl.gov.uk/corporate/about-tfl/4510.aspx It has three subsidiaries: London Transport Insurance Guernsey Ltd, the TfL Pension Fund Trustee Company and Transport Trading Ltd (TTL). TTL has six wholly-owned subsidiaries, one of which is London Underground Limited.http://www.tfl.gov.uk/corporate/about-tfl/boardandchiefofficers/1452.aspx
The TfL Board is chaired by the Mayor of London. The Mayor has vast powers of direction over TfL, sets TfL's budget (subject to the approval of the Greater London Assembly) and appoints its board. The Mayor also sets the structure and level of public transport fares in London. However the day-to-day running of the corporation is left to the Commissioner of Transport for London, who is currently Peter Hendy.
The Mayor is responsible for producing an integrated transport strategy for London and for consulting the GLA, TfL, boroughs and others on the strategy. The current Mayor's Transport Strategy was published on 10 July 2001. The GLA is consulted on the Mayor's transport strategy, and inspects and approves the Mayor's budget. It is able to summon the Mayor and senior staff to account for TfL's performance. London TravelWatch, a body appointed by and reporting to the Assembly, deals with complaints about transport in London.http://www.london.gov.uk/gla/transport.jsp
==Infrastructure==
===Stations and lines===
The London Underground's 11 lines are the Bakerloo line, Central line, Circle line, District line, Hammersmith & City line, Jubilee line, Metropolitan line, Northern line, Piccadilly line, Victoria line, and Waterloo & City line. Until 2007 there was a twelfth line, the East London line, but this has closed for conversion work and will have been transferred to the London Overground when it reopens in 2010. 
The Underground serves 268 stations by rail; an additional six stations that were on the East London line are currently served by Underground replacement buses. Fourteen Underground stations are outside Greater London, of which five (Amersham, Chalfont & Latimer, Chesham, Chorleywood, Epping) are beyond the M25 London Orbital motorway. Of the 32 London boroughs, six (Bexley, Bromley, Croydon, Kingston, Sutton and Hackney) are not served by the Underground. 
Lines on the Underground can be classified into two types: subsurface and deep-level. The subsurface lines were dug by the cut-and-cover method, with the tracks running about 5 m below the surface. The deep-level or tube lines, bored using a tunnelling shield, run about 20 m below the surface (although this varies considerably), with each track in a separate tunnel. These tunnels can have a diameter as small as 3.56 m (11 ft 8.25 in) and the loading gauge is thus considerably smaller than on the subsurface lines. Lines of both types usually emerge onto the surface outside the central area.
While the tube lines are for the most part self-contained, the subsurface lines are part of an interconnected network: Each shares track with at least two other lines. The subsurface arrangement is somewhat similar to the New York City Subway, which also runs separate "lines" over shared tracks.
===Rolling stock and electrification===
thumb|1996 Stock trains at Stratford Market Depot
The Underground uses rolling stock built between 1960 and 2005. Stock on subsurface lines is identified by a letter (such as A Stock, used on the Metropolitan line), while tube stock is identified by the year in which it was designed (for example, 1996 Stock, used on the Jubilee line). All lines are worked by a single type of stock except the District line, which uses both C and D Stock. Two types of stock are currently being developed — 2009 Stock for the Victoria line and S stock for the subsurface lines, with the Metropolitan line A Stock being replaced first. Rollout of both is expected to begin about 2009. In addition to the Electric-Multiple units described above, there are Engineering Stock, such as ballast trains and brake vans. They are identified by a 1-3 letter prefix, then a number. 
The Underground is one of the few networks in the world that uses a four-rail system. The additional rail carries the electrical return that on third-rail and overhead networks is provided by the running rails. On the Underground a top-contact third rail is beside the track, energised at +420 V DC, and a top-contact fourth rail is centrally between the running rails, at -210 V DC, which combine to provide a traction voltage of 630 V DC.
===Cooling===
===Planned improvements===
thumb|A diagram at Ealing Common, showing the layout of the Piccadilly line at London Heathrow Airport
There are many planned improvements to the London Underground. A new station opened on the Piccadilly line at Heathrow Airport Terminal 5 on 27 March 2008 and is the first extension of the London Underground since 1999.First Piccadilly line trains travel to Heathrow Terminal 5London Underground. Piccadilly line update. (21 August 2006). Retrieved 3 December 2006. Each line is being upgraded to improve capacity and reliability, with new computerised signalling, automatic train operation (ATO), track replacement and station refurbishment, and, where needed, new rolling stock. A trial program for a groundwater cooling system in Victoria station took place in 2006 and 2007; it aimed to determine whether such a system would be feasible and effective if in widespread use. A trial of mobile phone coverage on the Waterloo & City line aims to determine whether coverage can be extended across the rest of the Underground network. Although not part of London Underground, the Crossrail scheme will provide a new route across central London integrated with the tube network.
==Travelling on the London Underground==
===Ticketing===
The Underground uses TfL's Travelcard zones to calculate fares. Travelcard Zone 1 is the most central, with a boundary just beyond the Circle line, and Zone 6 is the outermost and includes London Heathrow Airport. Stations on the Metropolitan line outside Greater London are in special Zones 7-9, since January 2008.
The new zones 7-9 also apply on the Euston-Watford Junction line (part of the London Overground). With Watford High Street being within the zones, but at present (April 10, 2008), Watford Junction is outside of these zones and therefore a special train fare applies.
There are staffed ticket offices, some open for limited periods only, and ticket machines usable at any time. Some machines that sell a limited range of tickets accept coins only, other touch-screen machines accept coins and English (but not Northern Irish or Scottish) bank notes, and usually give change. These machines also accept major credit and debit cards: some newer machines accept cards only. In 2005 the Underground started to accept American Express.
More recently, TfL has introduced the Oyster card, a smartcard with an embedded contactless RFID chip, that travellers can obtain, charge with credit, and use to pay for travel. Like Travelcards they can be used on the Underground, buses, trams and the Docklands Light Railway. The Oyster card is cheaper to operate than cash ticketing or the older-style magnetic-strip-based Travelcards, and the Underground is encouraging passengers to use Oyster cards instead of Travelcards and cash (on buses) by implementing significant price differences. Oyster-based Travelcards can be used on National Rail throughout London. Pay as you go is available on a restricted, but increasing, number of routes.
====Penalty fares and fare evasion====
In addition to automatic and staffed ticket gates, the Underground is patrolled by both uniformed and plain-clothes ticket inspectors with hand-held Oyster card readers. Passengers travelling without a ticket valid for their entire journey are required to pay at least a £20 penalty fare and can be prosecuted for fare evasion under the Regulation of Railways Act 1889 under which they are subject to a fine of up to £1,000, or three months' imprisonment. Oyster pre-pay users who have failed to 'touch in' at the start of their journey are charged the 'maximum cash fare' (£4, or £5 at some National Rail stations) upon 'touching out'. In addition, an Oyster card user who has failed to touch in at the start of their journey and who is detected mid-journey (i.e. on a train) by an Inspector is now liable to a penalty fare of £20. No £4 maximum charge will be applied at their destination as the inspector will apply an 'exit token' to their card.
It should be noted that whilst the Conditions of Carriage require period Travelcard holders to touch-in and touch-out at the start and end of their journey, any Oystercard user who has a valid period Travelcard covering their entire journey is not liable to pay a Penalty fare where they have not touched-in. Neither the Conditions of Carriage or Schedule 17 of the Greater London Authority Act 1999, which shows how and when Penalty fares can be issued, would allow the issuing of a Penalty fare to a traveller who had already paid the correct fare for their journey.
right|thumb|Jubilee line platforms (London Bridge station)
===Delays===
According to statistics obtained under the Freedom of Information Act, the average commuter on the Metropolitan line wasted three days, 10 hours and 25 minutes in 2006 due to delays (not including missed connections).
 Between September 17 2006 and October 14 2006, figures show that 211 train services were delayed by more than 15 minutes.
 Passengers are entitled to a refund if their journey is delayed by 15 minutes or more due to circumstances within the control of TfL.
===Hours of operation===
The Underground does not run 24 hours a day, (except for at New Year and on major public events - such as the Queen's Golden Jubilee in 2002) because the majority of lines have only two tracks (one in each direction) and therefore need to close at night for planned maintenance work. First trains on the network start operating around 04:30, running until around 01:30. Unlike systems such as the New York City Subway, few parts of the Underground have express tracks that would allow trains to be routed around maintenance sites. Recently, greater use has been made of weekend closures of parts of the system for scheduled engineering work.
===Accessibility===
Accessibility by people with mobility issues was not considered when most of the system was built, and most older stations are inaccessible to disabled people. More recent stations were designed for accessibility, but retrofitting accessibility features to old stations is at best prohibitively expensive and technically extremely difficult, and often impossible. Even when there are already escalators or lifts, there are often steps between the lift or escalator landings and the platforms.
Most stations on the surface have at least a short flight of stairs to gain access from street level, and the great majority of below-ground stations require use of stairs or some of the system's 410 escalators (each going at a speed of per minute, approximately 1.65 miles per hour). There are also some lengthy walks and further flights of steps required to gain access to platforms. The station at Covent Garden has the equivalent of 15 storeys of steps to reach the exit, so an announcement is made for passengers to queue for a lift, as walking the steps can be dangerous.
The escalators in Underground stations include some of the longest in Europe, and all are custom-built. The longest escalator is at Angel station, 60 m (197 ft) long, with a vertical rise of 27.5 m (90 ft). They run 20 hours a day, 364 days a year, with 95% of them operational at any one time, and can cope with 13,000 people per hour. Convention and signage stipulate that people using escalators on the Underground stand on the right-hand side so as not to obstruct those who walk past them on the left.
TfL produces a map indicating which stations are accessible, and since 2004 line maps indicate with a wheelchair symbol those stations that provide step-free access from street level. Step height from platform to train is up to 300 mm, and there can be a large gap between the train and curved platforms. Only the Jubilee Line Extension is completely accessible.
TfL plans that by 2020 there should be a network of over 100 fully accessible stations, consists of those recently built or rebuilt, and a handful of suburban stations that happen to have level access, along with selected 'key stations', which will be rebuilt. These key stations have been chosen due to high usage, interchange potential, and geographic spread, so that up to 75% of journeys will be achievable step-free.
===Overcrowding===
Overcrowding on the Underground has been of concern, particularly at Camden Town station and Covent Garden, which merit access restrictions at certain times. Restrictions are introduced at other stations when necessary. Several stations have been rebuilt to deal with overcrowding issues, with Clapham Common and Clapham North on the Northern Line being the last remaining stations with a single narrow platform with tracks on both sides. At particularly busy occasions, such as football matches, British Transport Police may be present to help with overcrowding.
On 24 September 2007, King's Cross underground station was totally closed due to "overcrowding". According to a 2003 House of Commons report, commuters face a "daily trauma" and are forced to travel in "intolerable conditions".
===Safety===
thumb|Westminster station — extensive structures are required to support Portcullis House above.
Accidents on the Underground network, which carries around a billion passengers a year, are rare. There is just one fatal accident for every 300 million journeys.Safety first. The Economist (23 October, 2003) Retrieved 3 December, 2006. There are several safety warnings given to passengers, such as the traditional 'mind the gap' announcement and the regular announcements for passengers to keep behind the yellow line. Relatively few accidents are caused by overcrowding on the platforms, and staff monitor platforms and passageways at busy times prevent people entering the system if they become overcrowded. 
Most fatalities on the network are suicides. Most platforms at deep tube stations have pits beneath the track, originally constructed to aid drainage of water from the platforms, but they also help prevent death or serious injury when a passenger falls or jumps in front of a train and aid access to the unfortunate person. These pits are officially called "anti-suicide pits", colloquially "suicide pits" or "dead man's trenches". Delays resulting from a person jumping or falling in front of a train as it pulls into a station are announced as an "unfortunate delay", "passenger action", "customer incident" or "a person under a train", and are referred to by staff as a "one under". London Underground has a specialist "Therapy Unit" to deal with drivers' post-traumatic stress, resulting from someone jumping under their train. The Jubilee line extension is the first line to have platform edge doors. These prevent people from falling or jumping onto the tracks, but the main financial justification for their provision was to control station ventilation by restricting the 'piston-effect' of the moving air caused by the trains.
Terrorism in the London Underground has been a major concern because the Underground's importance makes it a prime target for attacks. Many warnings and several attacks, some successful, have been made on the Underground, the most recent on the 21 July 2005, although in that case only the detonators exploded. The most recent attack causing damage was on 7 July 2005, when three suicide bombers blew themselves up on three trains. The earliest attack on the London Underground was in 1885, when a bomb exploded on a Metropolitan line train at Euston Square station. The Provisional IRA (and its predecessors) carried out over ten separate attacks between 1939 and 1993.
Air pollution in the London underground has been the subject of concern. According to the Discovery Channel documentary, Underground Cities: London, inhaling fumes while travelling on London's Tube for 40 minutes is "the equivalent to smoking two cigarettes", however, the accuracy this information is disputed (see the main article for more information). This statement compares the weight of particulate matter that is breathed and not the health effects. Cigarette smoke consists of products of combustion containing oxides of carbon, nitrogen and sulphur; various alkaloids, aromatic hydrocarbons and tar. Dust in the Underground tunnels is mainly iron (from the wheel–rail interface), skin cells, hair cells and clothing fibres (from passengers), and quartz silica (from brakes). Weight for weight, tunnel dust has far less impact on human health than cigarette smoke.
Various regulations aim to improve safety on the Tube. Smoking was allowed in certain carriages in trains until July 1984. In the middle of 1987 smoking was banned for a six-month trial period in all parts of the Underground, and the ban was made permanent after the major King's Cross fire in November 1987., p19 Photography for personal use is permitted in public areas of the Underground,London Underground. Fiming & Photography - can I film/take photos on the Tube? Retrieved 3 December, 2006. but the use of tripods and other supports is forbidden as it poses a danger in the often cramped spaces and crowds found underground. Flash photography is also forbidden as it may distract drivers and disrupt fire-detection equipment. For the same reason bright auto-focus assist lights should be switched off or covered when photographing in the Underground.
The Underground's staff safety regimen has drawn criticism. In January 2002 it was fined £225,000 for breaching safety standards for workers. In court, the judge reprimanded the company for "sacrificing safety" to keep trains running "at all costs." Workers had been instructed to work in the dark with the power rails live, even during rainstorms. Several workers had received electric shocks as a result.Fine over workers' Tube danger. BBC News (10 January, 2002). Retrieved 3 December, 2006.
===Heathrow Stations===
image:HeathrowT123.jpg|Terminals 1-3 station
image:Heathrow Terminal 4 tube look east.JPG|Terminal 4 Station
image:Heathrow Terminal 4 tube roundel.JPG|Terminal 4 Roundel
image:Heathrow T5 station AB.JPG|Terminal 5 Station
==Image==
TfL's Tube map and "roundel" logo are instantly recognisable by any Londoner, almost any Briton, and many people around the world. The original maps were often street maps with the lines superimposed, and the stylised Tube map evolved from a design by electrical engineer Harry Beck in 1931. Virtually every major urban rail system in the world now has a map in a similar stylised layout and many bus companies have also adopted the concept. TfL licences the sale of clothing and other accessories featuring its graphic elements and it takes legal action against unauthorised use of its trademarks and of the Tube map. Nevertheless, unauthorised copies of the logo continue to crop up worldwide. The phrase "mind the gap," played when trains stop at certain platforms, has also become a well known catchphrase.
===The roundel===
The origins of the roundel, in earlier years known as the 'bulls-eye' or 'target', are obscure. While the first use of a roundel in a London transport context was the 19th-century symbol of the London General Omnibus Company — a wheel with a bar across the centre bearing the word GENERAL — its usage on the Underground stems from the decision in 1908 to find a more obvious way of highlighting station names on platforms. The red circle with blue name bar was quickly adopted, with the word "UNDERGROUND" across the bar, as an early corporate identity. Not accessible 2007-01-10 The logo was modified by Edward Johnston in 1919.
Each station displays the Underground roundel, often containing the station's name in the central bar, at entrances and repeatedly along the platform, so that the name can easily be seen by passengers on arriving trains. 
The roundel has been used for buses and the tube for many years, and since TfL took control it has been applied to other transport types (taxi, tram, DLR, etc.) in different colour pairs. The roundel has to some extent become a symbol for London itself.
===Typography===
Edward Johnston designed TfL's distinctive sans-serif typeface, in 1916. "New Johnston", modified to include lower case, is still in use. It is noted for the curl at the bottom of the minuscule l, which other sans-serif typefaces have discarded, and for the diamond-shaped tittle on the minuscule i and j, whose shape also appears in the full stop, and is the origin of other punctuation marks in the face. TfL owns the copyright to and exercises control over the New Johnston typeface, but a close approximation of the face exists in the TrueType computer font Paddington, and the Gill Sans typeface also takes inspiration from Johnston.
===Contribution to arts===
The Underground sponsors and contributes to the arts via its Platform for Art and Poems on the Underground projects. Poster and billboard space (and in the case of Gloucester Road tube station, an entire disused platform) is given over to artwork and poetry to "create an environment for positive impact and to enhance and enrich the journeys of…passengers". In addition, some stations' walls are decorated in tile motifs unique to that station, such as profiles of Sherlock Holmes's head at Baker Street, and a cross containing a crown at King's Cross St Pancras. Oval tube station has cricket-themed decorations, with murals, statues and banners all celebrating the game. Unique Edwardian tile patterns, designed by Leslie Green and installed in the 1900s, were also used on the platforms of many of the Yerkes-designed stations on the Bakerloo, Northern and Piccadilly lines. Many of these tile patterns survive, though a significant number of these are now replicas.
===In popular culture===
The Underground has been featured in many movies and television shows, including Sliding Doors, Tube Tales and Neverwhere. The London Underground Film Office handles over 100 requests per month. The Underground has also featured in music such as The Jam's "Down in the Tube Station at Midnight" and in literature such as the graphic novel V for Vendetta. Popular legends about the Underground being haunted persist to this day.
After placing a number of spoof announcements on her web page, London Underground voice over artiste Emma Clarke had any further contracts cancelled in 2007. 
==See also==
*7 July 2005 London bombings
*2007 Dean Farrar Street collapse
*British Transport Police
*Connect Project
*Docklands Light Railway
*(Croydon) Tramlink 
*Crossrail
*London Overground
*Inspector Sands
*Leinster Gardens
*List of London Underground-related fiction
*List of rapid transit systems
*London Post Office Railway and other features of Subterranean London
*London Underground air pollution
*Lots Road power station
*Mind the gap
*Mornington Crescent (game)
*Paddington Bear
*The London Game
*The Tube (London Underground TV series)
*Transport in London (overview)
*Underground Ernie
*London Underground anagram map
==References==
==Further reading==
* 
* 
* 
* 
* 
* Jackson, Alan & Croome, Desmond. Rails Through The Clay, Capital Transport 1993
* Lawrence, David. Underground Architecture, Capital Transport 1994
* Lee, Charles E. The Bakerloo line, a brief history, London Transport 1973 (and similar volumes covering other lines, published 1972-1976)
* Meek, James. London Review of Books, 5 May 2005, "Crocodile's Breath"
* Menear, Laurence. London's Underground Stations, a Social and Architectural Study, Midas Books 1983
* Rose, Douglas. The London Underground: A Diagrammatic History, Capital Transport 2005, ISBN 978-1-85414-315-0
* Saler, Michael. The Avant-Garde in Interwar England: 'Medieval Modernism' and the London Underground, Oxford University Press 1999
* Saler, Michael. "The 'Medieval Modern' Underground: Terminus of the Avant-Garde", Modernism/Modernity 2:1, January 1995, pp. 113-144 
* Wolmar, Christian. Down the Tube: the Battle for London's Underground, Aurum Press 2002
* Wolmar, Christian. The Subterranean Railway: How the London Underground Was Built and How It Changed the City For Ever, Atlantic 2004, ISBN 1-84354-023-1
==External links==
;Official
* Transport for London Home page
** Tube and DLR maps
** Facts and figures
** Tourist information
* British Transport Police
* London Transport Museum
;Technical
* Clive Feather’s highly detailed Underground Line Guides
* Richard’s LU rolling stock page
* Technical Service Maps BCV/SSL/Tube Lines etc Technical Maps
* Tube Professionals’ RUmour NEtwork The Tubeprune
* Stephen Knight’s London Underground Track Maps (Site broken. Archived version on the Internet Archive.)
;Visual
* London's Transport Museum Photographic Collection — A site of historical Transport for London images
* Photographs of London Underground
* London Underground Edwardian Tile Patterns
* London Underground Photos
* Tube Architecture
;Other
* Going Underground
* London Underground, the song by Adam Kay & Suman Biswas; warning! explicit content
* London Underground Tube Diary and Blog — commuters' blog
* London Underground Trivia
* Disused Stations on London's Underground
* London's Abandoned Tube Stations
* Index to London Underground History - A timeline of the London Underground
* alwaystouchout.com — a database of transport projects proposed or under way in London, including Underground projects
* Old Tube Architecture conservation — Victorian artefacts in need of protection.
* CityMayors article on history
* CityMayors article on PPP
* 
* London underground
Category:Electric railways
 
Category:London organisations
Category:Rail transport in London
Category:Busking venues
Category:1863 establishments
Category:Underground rapid transit systems
Category:Subterranean London