History UsefulNotes / TheLondonUnderground

* '''Mildmay Line:''' A combination of the North London and West London Lines. Joining the Overground in 2007, this is an orbital line that goes from Stratford in the east to Willesden Junction in the west across the north of London, before travelling south to Richmond. A branch also takes many services along the West London Line to Clapham Junction; when combined with the Windrush Line this forms a proper orbital loop around the city. Between Richmond and Gunnersbury, the Midmay Line shares tracks and stations with the Underground's District Line. As North London is largely electrified with overhead wires while South London uses third rail, trains on this line switch between the two modes mid-service. The line is named after Mildmay Hospital, Europe's first hospital dedicated to the treatment of HIV and AIDS.

* '''East London Line:''' Redevelopment of the East London Line is the genesis of the Overground's existence, and brings with it a long and convoluted history. First opened in phases between 1869 and 1884 as a north-south railway line in the east of London, it effectively served as a branch of the Metropolitan Line and its predecessors. In 1933, it became its own quasi-independent Underground line, which over time became further separated from the Metropolitan to the point where it eventually became fully independent from its parent line. For several decades it was the red-haired step child of the Underground, served by whatever spare trains the Underground had at any one time while seeing poor investment and service cutbacks. In 2007, the line was closed in order to significantly extend the line on both ends and create a connection with the South London Line; the new, improved East London Line opened as part of the Overground in 2010. Services today start in the north at either Dalston Junction or Highbury & Islington, and travel south to the choice of New Cross, West Croydon or Crystal Palace, or alternatively west to Clapham Junction as part of the now-integrated South London Line. The Underground-era color assigned to the East London Line was orange, which served as the inspiration for the Overground's color scheme as a whole. The East London Line features the Overground's main section of in-tunnel running, and at Whitechapel you can even catch a glimpse of Overground trains running underneath Underground trains. The East London Line also features the Overground's 'secret' station at Battersea Park, which sees one late-night service per day as a relic of the South London Line's former service pattern.

* '''North London Line:''' Joining the Overground in 2007, this is an orbital line that goes from Stratford in the east to Willesden Junction in the west across the north of London, before travelling south to Richmond. A branch also takes many services along the West London Line to Clapham Junction; when combined with the East London Line this forms a proper orbital loop around the city. Between Richmond and Gunnersbury, the North London Line shares tracks and stations with the Underground's District Line. As North London is largely electrified with overhead wires while South London uses third rail, trains on this line switch between the two modes mid-service.

* '''Watford DC Line:''' Opened in 1912 and joining the Overground in 2007, this is the commuter line from Euston Station to the suburb of Watford, taking its name from the fact that it is electrified by DC third rail in contrast to the West Coast Main Line it runs alongside. It is noteworthy for sharing a significant portion of its track with the above-ground portion of the Bakerloo Line; seeing the Overground and Bakerloo trains side-by-side is a great way of illustrating just how tiny the latter are. In the period when the line was part of Network [=SouthEast=], it had the far more fun name of the "Harlequin Line", referring to the Harlesden and Queen's Park stops on the line.

* '''The GOBLIN:''' That's the [[FunWithAcronyms Gospel Oak to Barking Line]]. It is a combination of many random lines built since 1868, with its current alignment not being solidified until 1981. An unloved periphery route for much of its life, it was a candidate for closure in the 1960s and saw poor service in the decades since. It joined the Overground in 2007, when it was given more importance and investment as a crucial orbital line in the north of the city. It was electrified in 2018, and is also the location of the Overground's newest addition with Barking Riverside station, built to serve a new neighbourhood on the bank of the Thames.

* '''Lea Valley Lines:''' The Lea Valley Lines refer to several commuter lines which run from Liverpool Street to the Lower Lea Valley north of the station, The lines were electrified in the 1960s, and partially joined the Overground in 2015. Services to Enfield Town, Chingford and Cheshunt are all operated by the Overground, while longer services from Hertford East to Liverpool Street or Stratford are still operated on the National Rail network.

* '''Romford-Upminster Line:''' The odd one out of the bunch. The line opened in 1893 as a small branch line built primarily to allow goods trains to transfer between the Great Eastern Main Line and the London, Tilbury and Southend Main Line. It joined the Overground in 2015, where it sees a half-hourly shuttle service between the titular stations with a single stop in between at Emerson Park. It is the shortest Overground line at just 5.4km, and the only one that does not interchange with any other Overground line.

* In ''VideoGame/ModernWarfare 3'', one level involves the SAS being drawn into a chase through an Underground tunnel between a train and a pickup truck, then a violent crash and a running gunfight through the station.

* The Bakerloo line is a playable route in ''Train Sim World 2'' (the console version of the ''VideoGame/TrainSimulator'' series) and can be purchased for ''TSW'''s later sequels as DLC.

'''Nice colorful map up there.''' Indeed, the map itself is [[https://en.wikipedia.org/wiki/Tube_map also kind of famous]] -- it was designed by engineer Harry Beck in 1931 to be like a circuit diagram. The idea is that you don't need to know the line's exact shape, just where the stations are in relation to each other, so you can make everything clean and geometric.[[note]]This was back when the thought hadn't crossed anyone's mind. It's now basically [[SeinfeldIsUnfunny standard procedure]] on public transport maps.[[/note]] The disadvantage is that sometimes the map will make stations look farther apart than they really are (meaning you could easily [[https://www.youtube.com/watch?v=IrHRQSm6LIs walk the distance instead]]).

* '''Metropolitan Line:''' The longest of the subsurface lines and the oldest. This line bears the distinction of being the only Underground line with express services. It is one of only two Underground lines to cross the Greater London boundary and exit the M25 perimeter, the other being the Central Line. This line originates at Aldgate, sharing tracks with the Circle and Hammersmith & City Lines through Baker Street, where it branches off to head northwest. It then travels nonstop to Finchley Road. From Finchley Road to Wembley Park, the Metropolitan Line trains run along a quadruple tracked line that they share with the Jubilee Line, with the Jubilee Line functioning as the local service while Metropolitan Lines run nonstop to Wembley Park. After Wembley Park, the Jubilee Line splits off to run north to Stanmore while the Metropolitan Line takes on a quadruple track form with two tracks for "fast" and "semi-fast" trains, and two more for "all stations" trains. After Harrow-on-the-Hill, a branch line to Uxbridge splits off, which is shared with the Piccadilly Line west of Rayners Lane, and the only one of the branches to terminate within Greater London. After Moor Park, the next branch line, the Watford branch, splits off, terminating at Watford in Hertfordshire while the main line continues into Buckinghamshire. Then at Chalfont and Latimer, a short single track branch to Chesham splits away, before the main line terminates at Amersham.

* '''Bakerloo Line:''' This line runs from Harrow & Wealdstone in suburban northwest London to Elephant & Castle in south London, via the West End. It is so named because it serves ''Baker'' Street and Water''loo''. Most trains only run the underground section from Elephant & Castle to Queen's Park, with only a third of trains going the rest of the way to Harrow & Wealdstone. The above-ground section is shared with the London Overground's Watford DC Line. Originally, the line travelled all the way to Watford Junction, but was cut back to Stonebridge Park in 1982, then restored to Harrow & Wealdstone in 1984. The line also used to have a second branch from Baker Street to Stanmore, which was severed and redesignated as the Jubilee Line in 1979. The line is equipped with the 1972 Stock, which are the oldest trains in operation on the Underground.

* "853-5937" by Music/{{Squeeze}} describes Mill Hill as "the end of the Earth on the Northern Line".

-->''"Mind the gap!"''

* Music/{{Madness}} is associated with a roundel for the invented Cairo East station, which appeared on the cover of their second album ''Music/{{Absolutely}}'' and shows up in concerts and music videos every so often.

'''Nice colorful map up there.''' Indeed, the map itself is [[https://en.wikipedia.org/wiki/Tube_map also kind of famous]] -- it was designed by engineer Harry Beck in 1931 to be like a circuit diagram. The idea is that you don't need to know the line's exact shape, just where the stations are in relation to each other, so you can make everything clean and geometric.[[note]]This was back when the thought hadn't crossed anyone's mind. It's now basically [[SeinfeldIsUnfunny standard procedure]] on public transport maps.[[/note]] The disadvantage is that sometimes the map will make stations look farther apart than they really are (meaning you could easily walk the distance instead).

Four of the eleven London Underground lines are subsurface lines. They are best defined by featuring tunnels just below the surface and of a similar size to those on British main lines. They also all radiate off a circular loop around Central London, sharing tracks with one another. The Hammersmith & City and Circle lines share all their stations and most of the track with other lines. All four subsurface lines share a uniform fleet of trains, the S Stock, which are also the only trains on the system to allow you to move between cars while the train is in motion.[[note]]Though it should be noted that there are two distinguishable variants to the S Stock: the inner-city District, Hammersmith & City and Circle lines use S7 Stock trains, which have seven cars and all-longitudinal seating as befitting the higher passenger traffic closer to central London. The Metropolitan line uses S8 Stock trains, which have eight cars, and like the A Stock trains they replaced, have a mix of transverse and longitudinal seating on account of the longer journeys passengers are making from the far outer suburbs.[[/note]]

* '''Victoria Line:''' The Victoria Line runs from Walthamstow Central in the north to Brixton in the south. It bears the distinction of being one of only two lines to run completely below ground, the other being the Waterloo & City Line. It was opened in 1969 as a reliever line to take traffic off the adjoining Northern and Piccadilly Lines. This is evident in that only station on the line, Pimlico, is not an interchange with another Underground or rail line, and that station was only added to the plans after construction on the line began. This line is also noteworthy for the fact that several existing stations were rearranged to allow for cross-platform interchanges with it (to the Bakerloo Line at Oxford Circus, to the Northern Line Bank Branch at Euston, the Northern City Line at Highbury & Islington, and the Piccadilly Line at Finsbury Park). The Victoria Line uses 2009 Stock.

* ''Film/BillyElliot'' takes place mostly during the 1984 miners' strike, but has a coda set in the present day. The transition in time between the past and the present is indicated by Billy's family arriving at one of the distinctively modern stations of the Jubilee Line extension.

* '''Jubilee Line:''' Originally planned to be known as the Fleet Line, the Jubilee Line is the newest of the deep tube lines, and is a blend of some of the oldest and newest sections of Underground tracks. The Jubilee Line can trace its roots back to 1932, when the Metropolitan Railway built a branch from their main line at Wembley Park to Stanmore. The line, as with many others in the northwest London area, was designed to absorb commuter traffic from the new and rapidly expanding suburbs. This became a branch of the Bakerloo line in 1932, and operated that way until 1979, when it was split off from the Bakerloo line with a new section of tube track from Baker Street to Charing Cross and given its own identity. The Jubilee Line was named in honor of Queen Elizabeth II's Silver Jubilee, hence the silver color on the Tube map. The line originates at Stanmore in northwest London, and travels along a four stop double-track line until Wembley Park, where it meets the Metropolitan Line. It then runs locally along the shared right-of-way to Finchley Road,[[note]]Metropolitan Line trains do not call at the intermediate stations of West Hampstead, Kilburn, Willesden Green, Dollis Hill or Neasden. However, Willesden Green and Neasden stations have platforms on the Metropolitan line tracks, which are used during service disruptions or irregular occasions when local events can cause a heavy increase in use of the stations.[[/note]] where it descends underground. After Baker Street, where nonrevenue track connections to the Bakerloo Line still exist, the Jubilee line enters the 1979 segment and continues south to Green Park, the last stop of the original 1979 section. Here, trains originally turned east to terminate at Charing Cross. This was how the line worked until 1999, when Charing Cross was bypassed by another extension.[[note]]Charing Cross's platforms are kept in use for filming tube scenes with a 21st century setting[[/note]] From here, the Jubilee Line tunnels under the Thames four times as it travels through East London, Canary Wharf, and North Greenwich. After North Greenwich, the line comes above ground near Canning Town and runs parallel to a Docklands Light Railway line the rest of the way to Stratford. The stations on the 1999 section of the Jubilee Line are unique for being the only section of Underground to have platform edge doors.[[note]]They are also truly enormous and cavernous spaces. Canary Wharf has been compared to a cathedral, with it being so spacious that you could fit One Canada Square into it if laid on its side with room to spare. Westminster has a dramatic vertical void nearly 40 m (130 ft) deep, and just digging out the void required propping up Big Ben with tons of concrete underneath to prevent it from falling into the hole. This is always possible in London because it's built on soft clay rather than solid rock, and especially as this is on the bank of the River Thames. It's quite an engineering achievement. Big Ben is monitored in case of further movement. The reasons why these stations are so big is because [=TfL=] was as a response to safety concerns—overcrowding and a lack of exits had been significant factors in the 1987 King's Cross fire—as well as [[CrazyPrepared an attempt to future-proof stations by designing them from the start for a high use]]. These platforms are really only full at the height of rush hour; they all provide step-free access, dual exits at either platform ends, ventilation, as well as fireproof lifts. To ease flow, extra escalators (at least 3 per station) were installed, totalling 115 over the entire extension, increasing the total number of escalators over the entire Underground network by almost half.[[/note]] The Jubilee Line is operated with 1996 Stock.

* '''Northern Line:''' The Northern Line is a bit of a misnomer. It does not serve the northernmost stations on the network, though it does serve the ''southern''most station, Morden, as well as 18 of the system's 31 stations south of the River Thames. The line was formed from the merger of three older railways: the Charing Cross, Euston & Hampstead Railway, the City & South London Railway, and the Edgware, Highgate & London Railway. As a result, it has a very complex configuration where there are three northern branches and two branches through central London. The Bank branch covers the former C&SLR track. It originates at Morden in far south London, and travels north along an underground route until Kennington, where it meets the Charing Cross branch. From Kennington to Camden Town, it travels via the Financial District and Bank, reconvening with the Charing Cross branch at Camden Town. Meanwhile, the Charing Cross branch makes up the former CCE&HR trackage. It originates at Battersea Power Station south of the Thames. After stopping at Nine Elms, it interchanges with the Bank branch at Kennington. From here, it travels to Camden Town via the West End. After the central branches merge at Camden Town, the line splits into the two northern branches, one traveling northwest on former CCE&HR trackage to Edgware while the other goes due north on former EH&LR trackage to High Barnet, with an additional shuttle spur from Finchley Central to Mill Hill East. In the current service pattern, half the trains from each northern branch are routed onto the Bank branch and travel all the way to Morden, while the other half are routed via the Charing Cross branch and terminate either at Battersea Power Station or on a balloon loop at Kennington.[[note]]During peak hours, there are a limited number of trains routed via the Charing Cross branch that switch over to the Bank branch and continue south to Morden after Kennington. All Night Tube operations are also routed via the Charing Cross branch[[/note]] It is the location of the system's most recent addition: A short branch from Kennington to the aforementioned Battersea Power Station with Nine Elms as an intermediate station. The Northern Line uses 1995 Stock trains, which have identical car bodies to the Jubilee Line's 1996 Stock but are internally different.[[note]]Both stocks were manufactured by Alstom, but the 1995 Stock is more technologically advanced than the 1996 Stock, and have just six cars instead of seven (although the 1996 Stock were originally six car trains until 2005 when a capacity upgrade led to the addition of four extra trainsets of 1996 Stock plus the addition of a seventh car on every existing train) and have quieter traction motors than the 1996 Stock.[[/note]]

* '''Piccadilly Line:''' The Piccadilly Line originates at Cockfosters in suburban north London, and after traversing through Central London, comes above ground at Hammersmith. From here, the line runs express, to the inside of the "local" tracks of the District Line, until Acton Town, where it splits into two long branches. Half of the trains operate on the Uxbridge Branch; they head northwest to Rayners Lane, where they join the Metropolitan Line's Uxbridge Branch and operate over that to Uxbridge (making for the only stretch of Underground track where subsurface and deep tube trains operate on the same tracks as opposed to just have cross-platform transfers). The other half turn southwest and travel out to London Heathrow Airport. Due to the complex arrangement of the tube tracks at Heathrow, half of the Heathrow trains terminate at Terminal 4 on a balloon loop, while the other half terminate at Terminal 5 (meaning that some passengers may have to travel to Hatton Cross and backtrack if changing terminals at Heathrow via tube). The line operates with 1973 Stock.

* '''Victoria Line:''' The Victoria Line runs from Walthamstow Central in the north to Brixton in the south. It bears the distinction of being one of only two lines to run completely below ground, the other being the Waterloo & City Line. It was opened in 1969 as a reliever line to take traffic off the adjoining Northern and Piccadilly Lines. This is evident in it has just one station that is not an interchange with another Underground or rail line, Pimlico, and that station was only added to the plans after construction on the line began. This line is also noteworthy for the fact that several existing stations were rearranged to allow for cross-platform interchanges with it (to the Bakerloo Line at Oxford Circus, to the Northern Line Bank Branch at Euston, the Northern City Line at Highbury & Islington, and the Piccadilly Line at Finsbury Park). The Victoria Line uses 2009 Stock.

Confusingly, the modern Tube map includes a lot of lines that aren't technically part of the Underground proper -- the orange lines are London Overground lines (former commuter lines that were shifted to be more integral to the system), and the Docklands Light Railway is an automated light metro system that's not part of the Underground but really might as well be, serving an area of East London that is very lacking in Tube service. On some maps, you might get lucky and see the Croydon Tramway or the Emirates Air Line (a gondola across the Thames that was really just a tourist thing for the 2012 Olympics). Lines have shifted a lot over the years -- not only have new ones been built, but some stations have been decommissioned or moved to other lines, so it's not so easy to make the map period-accurate.

Established in 2007, the London Overground was created to provide some much-needed attention to London's various orbital and periphery lines, which during the previous decades were left wanting for serious investment and steady levels of service. It is owned by Transport for London, but operated via a concession currently held by Arriva; a model that served as a major inspiration for the reform of the wider national railway system in the 2020's. Taken as a whole, the London Overground can be a bit confusing to decipher as there are few transfers and connections between lines of the kind that you may expect if you imagine the Overground just a second tube network, but it is best as a collection of separate lines which serve some of the lesser-known parts of the city.

* '''The GOBLIN:''' That's the [[FunWithAcronyms Gospel Oak to Barking Line]]. It is a combination of many random lines built since 1868, with its current alignment not being solidified until 1981. An unloved periphery route for much of its life, it was a candidate for closure in the 1960's and saw poor service in the decades since. It joined the Overground in 2007, when it was given more importance and investment as a crucial orbital line in the north of the city. It was electrified in 2018, and is also the location of the Overground's newest addition with Barking Riverside station, built to serve a new neighbourhood on the bank of the Thames.

* '''Lea Valley Lines:''' The Lea Valley Lines refer to several commuter lines which run from Liverpool Street to the Lower Lea Valley north of the station, The lines were electrified in the 1960's, and partially joined the Overground in 2015. Services to Enfield Town, Chingford and Cheshunt are all operated by the Overground, while longer services from Hertford East to Liverpool Street or Stratford are still operated on the National Rail network.

* '''Thameslink:''' The biggest transit network in the city not owned or operated by Transport for London. Thameslink is a commuter network that serves a large number of surrounding towns and cities, seeing trains travel as far north as Peterborough and as far south as Brighton. Within London, services are centred on the Snow Hill tunnel, which opened in 1866 to allow freight and passenger services to travel straight through the City of London, connecting railways south of the Thames to the Metropolitan Railway's widened lines in the north. The vision to take advantage of the potential of this route was acted on in the 1980's, with the line being electrified in 1982 and Thameslink services beginning in 1988. A massive further overhaul in the line began in 2007, creating the line as it exists today. It operates in the style of a German S-Bahn system, with trains north and south of the central section diverging to serve a wide net of different stations, before converging in the middle to provide a high frequency in the city core between St. Pancras and Blackfriars that reaches as high as 24 trains per hour in the off-peak, a rate that rivals or even surpasses many sections of the Underground. As part of the 2007 refurbishment, a branch that takes the Thameslink line alongside the subsurface Underground lines to Blackfriars and Moorgate were abandoned in order to facilitate longer 12-car trains on the remainder of the line; these abandoned platforms are still very clearly visible today. Over the years, Thameslink has been on and off the Tube map depending on the whims of the map makers at any given moment; in 2020 the system returned to the map where it is represented in light pink.

* '''South London Railways:''' Looking at a Tube map, you may notice that the vast majority of the Underground is located above the Thames. South of the river, railroad tycoons of the day recognised both the much lower building density and the soil conditions of the area made constructing traditional railways the way to go.[[note]]Also, the railway companies south of the Thames, crammed into a relatively small region of the country, generally did not have the massive freight traffic and long-distance passenger services that sustained the northern companies, and needed commuter traffic more as an income source.[[/note]] Railway barons of this era were also not the most collaborative sort, with almost all of the projects that sprung up during the 1800's being business ventures that often competed with each other for passengers and traffic. The result today is spaghetti, with an often nonsensical but vast commuter network springing from London's various south-facing railway termini. This is a double-edged sword, as South London has a railway network that counts itself as one of the densest in the world, but it is held back by a jumbled layout and a need to share sections with intercity services and other lines, which limits frequencies and can easily create a set of cascading delays if just one thing goes wrong somewhere in the region. It is part of Transport for London's long-term ambition to acquire all of these commuter lines and sort them into a more reliable and well-organised railway network, whether as part of the Overground or as a more distinct metro system, but time will tell when this will happen. Fairly uniquely by world standards, much of Southern England as a whole is electrified using third rail, a contrast to the preference for overhead wires for the vast majority of main line operations.

* In ''Series/{{Thunderbirds}}'', one episode involves Scott and Virgil having to use abandoned London Underground tunnels in order to get into the Bank of England's vault. This is surprisingly realistic, as the Central Line goes right past there (following the streets above). Then they go and ruin it by starting at Piccadilly Circus.

Entire books have been written about the Underground, and as UsefulNotes is meant to be useful to aspiring writers and critics (and not {{railfan}}s), we're here to tell you what you need to know about the Underground so as to [[CriticalResearchFailure not look like a complete idiot]].

[[quoteright:350:https://static.tvtropes.org/pmwiki/pub/images/london_tube_map_2019.png]]
[[caption-width-right:350:Roll a 6 to start.]]

[[folder:Film]]

* '''East London Line:''' Redevelopment of the East London Line is the genesis of the Overground's existence, and brings with it a long and convoluted history. First opened in phases between 1869 and 1884 as a north-south railway line in the east of London, it effectively served as a branch of the Metropolitan Line and its predecessors. In 1933, it became its own quasi-independent Underground line, which over time became further separated from the Metropolitan to the point where it eventually became fully independent from its parent line. For several decades it was the red-haired step child of the Underground, served by whatever spare trains the Underground had at any one time while seeing poor investment and service cutbacks. In 2007, the line was closed in order to significantly extend the line on both ends and create a connection with the South London Line; the new, improved East London Line opened as part of the Overground in 2010. Services today start in the north at either Dalston Junction or Highbury & Islington, and travel south to either New Cross or West Croydon, or west to Clapham Junction as part of the now-integrated South London Line. The Underground-era color assigned to the East London Line was orange, which served as the inspiration for the Overground's color scheme as a whole. The East London Line features the Overground's main section of in-tunnel running, and at Whitechapel you can even catch a glimpse of Overground trains running underneath Underground trains. The East London Line also features the Overground's 'secret' station at Battersea Park, which sees one late-night service per day as a relic of the South London Line's former service pattern.

* '''Romford-Upminster Line:''' The odd one out of the bunch. The line opened in 1893 as a small branch line built primarily to allow goods trains to transfer between the Great Eastern Main Line and the London, Tilbury and Southend Main Line. It joined the Overground in 2015, where it sees a half-hourly shuttle service between the titular stations with a single stop in between at Emerson Park. It is the shortest Overground line at just 5.4km.

* '''Victoria Line:''' The Victoria Line runs from Walthamstow Central in the north to Brixton in the south. It bears the distinction of being one of only two lines to run completely below ground, the other being the Waterloo & City Line. It was opened in 1969 as a reliever line to take traffic off the adjoining Northern and Piccadilly Lines. This is evident in how every station apart from Pimlico and Blackhorse Road was built as an interchange station, the larger intervals between stations, and the fact that several existing stations were rearranged to allow for cross-platform interchanges with it (to the Bakerloo Line at Oxford Circus, to the Northern Line Bank Branch at Euston, the Northern City Line at Highbury & Islington, and the Piccadilly Line at Finsbury Park). The Victoria Line uses 2009 Stock.

* '''Elizabeth Line:''' The newest major addition to London's railways, and a successor of sorts to Thameslink. The Elizabeth Line, known prior to opening as Crossrail, involves major improvements to the commuter sections of the Great Western and Great Eastern Main Lines, and then connecting the two with a tunnel under the city designed to serve as an express and relief line for the Underground. Two branches also see the line serve Heathrow Airport on its western end, and the London Docklands with a connection to Abbey Wood in the south. The core section of the line was [[ScheduleSlip supposed to open in 2018]] and is now promised for "the first half of 2022", while the existing eastern and western suburban services intended to be taken over by it are operating under the temporary banner of [=TfL=] Rail.

* '''GOBLIN Line:''' That's the [[FunWithAcronyms Gospel Oak to Barking Line]]. It is a combination of many random lines built since 1868, with its current alignment not being solidified until 1981. An unloved periphery route for much of its life, it was a candidate for closure in the 1960's and saw poor service in the decades since. It joined the Overground in 2007, when it was given more importance and investment as a crucial orbital line in the north of the city. It was electrified in 2018, and is also the location of the Overground's newest addition with Barking Riverside station, built to serve a new neighbourhood on the bank of the Thames.

* '''Romford-Upminster Line:''' The odd one out of the bunch. The line opened in 1893 as a small branch line built primarily to allow goods trains to transfer between the Great Eastern Main Line and the London, Tilbury and Southend Main Line. It joined the Overground in 2015, where it sees a half-hourly shuttle service between the titular stations with a single stop in between at Emerson Park. It is the shortest Overground line at 5.4km