London Underground

2008/9 Schools Wikipedia Selection. Related subjects: Engineering; Railway transport

London Underground
Locale	Greater London, Chiltern, Epping Forest, Three Rivers and Watford
Transit type	Rapid transit
Began operation	1863
System length	408 km (254 mi)
No. of lines	12
No. of stations	275 served (253 owned)
Daily ridership	3 million (approximate)
Track gauge	Template:Standard gauge (standard gauge)
Operator(s)	Transport for London

Part of a series of articles on The Tube
Overview History Infrastructure Stations Trains Popular Culture Map London Transport Portal

The London Underground is a railway system - also known as a rapid transit system - that serves a large part of Greater London, United Kingdom and some neighbouring areas. It is the world's oldest underground 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 cylindrical shape of the system's deep-bore tunnels.

The Underground has 276 stations and runs over 243 miles (408 km) of line, making it the longest underground railway in the world, and one of the most served in terms of stations. There are also numerous closed stations. In 2005 971 million passengers used the Underground and for the first time ever in 2007, over one billion passengers were recorded. As of March 2007, just over 3 million passengers use the Underground each day, with an average of 3.4 million passengers on weekdays.

Since 2003, the Underground has been part of Transport for London (TfL), which also administers numerous other transport-related functions, including the famous red double-decker buses. The former London Underground Limited was a subsidiary of London Regional Transport, a statutory corporation.

History

The first section of the Metropolitan Railway and of the London Underground ran between Paddington (Bishop's Road), now Paddington, and Farringdon Street, now Farringdon, and was the world's first urban underground passenger-carrying railway. It was built as dual gauge – able to accommodate both Brunel's ' broad gauge' (7 ft ¼in / 2.14 m) trains as well as the 4 ft 8½in (1.435 m) ' standard gauge' of the other trains serving London. Following delays for financial and other reasons after the railway was authorised in 1854, public traffic began on 10 January 1863. 30,000 passengers were carried that day, with trains running every ten minutes; by 1880 the expanded 'Met' was carrying 40 million passengers a year. Other lines swiftly followed, and by 1884 the Inner Circle (today's Circle line) was complete.

The early tunnels were dug using cut-and-cover construction methods. This included the District line, which necessitated the demolition of a number of houses over the site of the line between Paddington and Bayswater.

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.

Advances in electric traction allowed later tunnels to be deeper underground than the original cut-and-cover method allowed, and deep-level tunnel design improved, including the use of tunnelling shields. The City & South London Railway (now part of the Northern line), the first "deep-level" line and electrically operated, opened in 1890.

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 Great Northern & Strand Railway, the Brompton & Piccadilly Circus Railway (jointly to become the Great Northern, Piccadilly & Brompton Railway, the core of the 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. On 1 January 1913 the UERL absorbed two other independent tube lines, the C&SLR and the Central London Railway, 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.

The 1930s and 1940s

In 1933 the Combine and all the municipal and independent bus and tram undertakings were merged into the London Passenger Transport Board (LPTB), a public corporation that approximated in scope to the present-day TfL. It set in motion a scheme for expansion of the network, the 1935–1940 New Works programme, to extend some lines and to take over the operation of others from the main-line railway companies, but the outbreak of World War II froze all these schemes.

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.

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

Following the war, travel congestion continued to rise. The LPTB and its successor the London Transport Executive undertook a programme of war repair and improvement works during the 1940s and 1950s though little money was provided for expansion or improvements to the system. The first real investment came with the carefully planned Victoria line on a diagonal northeast-southwest alignment beneath central London, 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 1999 the Jubilee was extended to Stratford in London's East End, including the completely refurbished interchange station at Westminster, in several stages. The Jubilee's old terminal platforms at Charing Cross were abandoned but maintained operable for emergencies.

Since January 2003 the Underground has been operated as a Public–Private Partnership (PPP), where the infrastructure and rolling stock are maintained by two private companies ( Metronet and Tube Lines) under 30-year contracts, but it remains 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, 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.

Infrastructure

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.

Rolling stock

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.

Stations

The Underground serves 268 stations by rail. An additional seven locations are served by the replacement bus services for the East London line that will be offered until the East London line Extension opens as part of the London Overground in 2010. Fourteen Underground stations are outside Greater London, of which five ( Amersham, Chalfont & Latimer, Chesham, Chorleywood, Epping) are beyond the M25 London Orbital motorway.

Lines

The table below lists each line; the colour used to represent each on Tube maps, the date the line became operational and the first section opened (not necessarily under the current line name), the date the line gained its current name, and the type of tunnel used in the central area.

London Underground lines

Name	Map colour	First operated	First section opened *	Name dates from	Type	Length /km	Length /miles	Stations	Journeys per annum (000s)	Average journeys per mile (000s)
Bakerloo line	Brown	1906	1906	1906	Deep level	23.2	14.5	25	95,947	6,617
Central line	Red	1900	1856	1900	Deep level	74	46	49	183,582	3,990
Circle line	Yellow	1884	1863	1949	Subsurface	22.5	14	27	68,485	4,892
District line	Green	1868	1858	1868-1905	Subsurface	64	40	60	172,879	4,322
East London line (currently closed until 2010, reopening as London Overground)	Orange	1884	1869	1980s	Subsurface	7.4	4.6	8	10,429	2,267
Hammersmith & City line	Pink	1863	1858	1988	Subsurface	26.5	16.5	28	45,845	2,778
Jubilee line	Grey	1979	1879	1979	Deep level	36.2	22.5	27	127,584	5,670
Metropolitan line	Corporate Magenta	1863	1863	1863	Subsurface	66.7	41.5	34	53,697	1,294
Northern line	Black	1890	1867	1937	Deep level	58	36	50	206,734	5,743
Piccadilly line	Dark Blue	1906	1869	1906	Deep level	71	44.3	52	176,177	3,977
Victoria line	Light Blue	1968	1968	1968	Deep level	21	13.25	16	161,319	12,175
Waterloo & City line	Teal	1898	1898	1898	Deep level	2.5	1.5	2	9,616	6,410
* Where a year is shown that is earlier than that shown for First operated, this indicates that the line operates over a route first operated by another Underground line or by another railway company.

Subsurface versus deep-level tube lines

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. Trains on the subsurface lines slightly exceed the standard British loading gauge.
• 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 lined with cast-iron or precast concrete rings. 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, except the Victoria line, which is in tunnel except for its depot, and the very short Waterloo & City line, which runs entirely in the central area and has no surface section. Only 45% of the Underground is in tunnel.

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.

Non-served areas

Six of the 32 London boroughs are not served by the Underground. Five of these are south of the River Thames: Bexley, Bromley, Croydon, Kingston and Sutton. This lack of lines and stations is sometimes attributed to the geology of that area, the region being almost one large aquifer. Another reason is that during the great period of tube-building in the early 20th century south London was already well served by the efficiently-run suburban lines of the London and South Western Railway, London, Brighton and South Coast Railway and the South Eastern and Chatham Railway, then being electrified, which obviated the need for Underground expansion into those areas. Suburban traffic was essential to the viability of the southern railways, while railways to the north and west were able to focus on long-distance traffic, which was profitable and was not subject to the short-term traffic peaks of suburban traffic. In contrast, suburban traffic obstructed their long-distance operations and required substantial infrastructure investment, without providing compensating returns.

The sixth unserved borough is Hackney, with the exception of Manor House and Old Street stations just outside its boundary. The borough is however served by the London Overground. This is a new metro-style railway which runs the North London Line. It is to take over the East London line (when its extension opens, scheduled for 2010) to form an almost orbital railway round London.

International connections

The Underground serves Heathrow Airport for national and international flights; and St Pancras International (via King's Cross St. Pancras) for Eurostar services to mainland Europe, via the Channel Tunnel.

Electrification

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.

Most tube lines run in cast-iron tunnels (only some of the more recent constructions use concrete tunnel lining). Using a third-rail scheme necessitates that the return current is conducted through one (earthed) running rail. Such current is just as easily able to travel through the cast-iron tunnel lining, and unless the joints between the sections are electrically sound, the current will arc across the sections causing considerable damage, or corrode the tunnel segments via electrolysis. There are also many cast-iron gas and water mains in the vicinity of the tube tunnels, and the return current would travel along these just as easily. Some of these mains date back to the 19th century and the joints between separate sections would certainly not have been designed to be electrically sound, as deep-level electric tube trains were some way off.

Another advantage of the fourth rail system is that the two running rails are available exclusively for track circuits, of which there are many.

The surface sections of the lines are constructed using fourth-rail purely to permit through running with the tube lines, there being no other technical reason to do so.

The traction current has no direct earth point, but there are two resistors connected across the traction supply. The centre tap of the resistors is earthed, establishing the reference point between the positive and negative rails by voltage division. The resistors are large enough to prevent large currents flowing through the earthed infrastructure. The positive resistor is twice as large as the negative resistor, since the positive rail carries twice the voltage of the negative rail.

Some above-ground sections are shared with National Rail trains which use the three-rail system. On these sections the fourth rail is bonded to the running rails, to keep it at earth potential, and the third rail is held at +630 volt DC.

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.

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 at least pay a £20 penalty fare and can be prosecuted for fare evasion under the Regulation of Railways Act 1889 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.

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.

Station access

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 145 ft (44 m) 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.

Safety

Suicides

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.

Accidents

The Underground network carries around a billion passengers a year. It is a very safe mass transport system, with just one fatal accident for every 300 million journeys.

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.

Terrorism

The Underground is an important part of everyday life for millions of people. This makes it a prime target for terrorists. 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.

Overcrowding

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. Camden Town station is exit-only on Sunday afternoons (13:00–17:30) for this reason, and Covent Garden has access restrictions at 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".

Smoking

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.

Air Pollution

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.

Photography

Photography for personal use is permitted in public areas of the Underground, 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.

Safety culture

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.

Age

Due to a combination of the age of the system and significant under-funding in the past, some parts of the Underground's infrastructure are substantially older than their equivalents in other cities. Recently the private infrastructure company Tube Lines was reported to be using online auction website eBay to find spare parts for some of its equipment which was so old that parts were otherwise unobtainable.

Future projects

Extensions and new stations

• A new station is being built on the Piccadilly line at Heathrow Airport Terminal 5. The extension, the first on the London Underground since 1999, consists of a two-platform station, two sidings where trains can be stabled, approximately 3 km of 4.5 m diameter bored tunnels, a ventilation shaft and two escape shafts. The works were completed in 2007, and final testing and commissioning are currently being carried out in preparation for opening in March 2008. When the junction between the extension and the Heathrow Loop was built, the tunnel between Terminal 4 and Terminals 1,2,3 was out of service but it re-opened on 17 September 2006. The extension is due to open in 2008.

• A new station at Wood Lane is due to open in 2008 to serve the new Westfield London shopping centre.

• The Bakerloo line may be re-extended to Watford Junction from its current terminus at Harrow & Wealdstone. This is part of the Transport 2025 strategy, but no more precise timescale has been announced.

• TfL and Hertfordshire County Council would like to connect the Watford branch of the Metropolitan line to the disused Croxley Green Network Rail branch, between Croxley Green and Watford West. A new station would be built at Ascot Road as a replacement for Croxley Green, Watford West would be heavily refurbished and Watford (Metropolitan) would close. This extension would bring the Underground back to central Watford and the important Watford Junction main-line station. The current timetable suggests a 2011 opening date, but the extension currently lacks funding and planning permission.

• The East London Line closed on 22 December 2007 to allow it to be extended north from Whitechapel along the old Broad Street viaduct to Dalston then along the North London Line to Highbury & Islington, and south to West Croydon, Crystal Palace and eventually Clapham Junction. When it reopens in 2010 (with the connection to Highbury & Islington due in 2011), it will be part of the new London Overground network, not of the Underground; however, it will still be run by TfL.

Line upgrades

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.

• During 2007, work began to install moving block signalling and ATO on the Jubilee line, for completion in 2009. When this work is complete, a similar upgrade will be performed on the Northern line, for completion in 2012. Both lines already have modern rolling stock.
• The Victoria line will receive new 2009 Stock trains from 2009 onwards. They will be higher in capacity and offer improved acceleration. A new ATO system will be brought into service once the old fleet has been withdrawn. When all upgrades are complete in 2013, train frequency will have improved from 28 trains per hour to 33 (averaging around a train every 1min40secs).
• The Metropolitan line, Hammersmith & City line, Circle line and District line will receive new S Stock trains, to be introduced in phases from 2009 to 2015. New trains will feature inter-car gangways enhancing passenger safety, regenerative braking leading to a 20-25% reduction in carbon dioxide emissions, and improved acceleration and braking allowing an increase in train frequency. The last trains to be replaced, 75 District line trains, are currently receiving interim refurbishment. Lines that are currently served by six-car trains will get seven-car trains, once necessary platform-lengthening works are completed.
• The Piccadilly line and Bakerloo line will receive new rolling stock and other upgrades by 2014 and 2020 respectively.

Upgrade programmes on the Waterloo & City line (without ATO) and Central line are largely complete.

Other projects

• Shepherd's Bush station on the Central line will be completely rebuilt above ground and below.
• Victoria and King's Cross St Pancras stations will have new passageways and an extra ticket hall each to improve capacity.
• In summer, temperatures on parts of the Underground can become very uncomfortable due to its deep, narrow and poorly ventilated tube tunnels: temperatures of 47 °C (117 °F) were reported in the 2006 European heat wave. Conventional air conditioning has been ruled out on the deep lines because of the lack of space for equipment on trains and the problems of dispersing the waste heat this would generate. A year-long trial of a groundwater cooling system began in June 2006 at Victoria station. If successful, the trial will be extended to 30 other deep-level stations. The Underground also advises passengers to carry a bottle of water to help keep cool. Waste heat disperses better in the subsurface tunnels and S Stock trains will have air-conditioning.

• On March 15, 2007 it was announced that there will be a trial of mobile phone coverage on the Waterloo & City line. At the earliest, the trial will start in April 2007, when coverage will be available on the platforms at Waterloo and Bank stations. After this, coverage will be extended to the tunnel between the two stations. The trial will look at the viability of extending coverage 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.

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. 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.

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 and Tube Tales; 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.