Berlin's rapid transit system is the poster child of a multiple Overly Narrow Superlative. Notable details are its legacy and the existence of two separate rapid transit systems. They have also made an extremely tacky promotional video that underwent Memetic Mutation despite its Forced Meme appearance.note
For a country of its size and degree of urbanization, Germany has surprisingly few cities with full-fleshed underground systems, especially in comparison to France. Only Berlin, Hamburg, Munich and Nuremberg have real U-Bahn systems. The name is commonly understood to stand for Untergrundbahn (literally "underground track"). U-Bahn trains are always run by the same company that also runs (most of) the city's buses and trams (where the latter exist). Unlike say the US (where there are separate tickets for e.g. Muni and BART in San Francisco) there is integrated ticketing, meaning your ticket is valid whether you take the U-Bahn, the S-Bahn, the tram or a bus and transfers are seamless from a ticketing standpoint.
There are several other cities that have rapid transit pretender systems note which may look like U-Bahn and have U designations, but they're rather cheap and dirty crossbreeds of undergrounds and streetcars/trams and therefore fall under the category of light rail systems.
- Transit planner note: Using lighter vehicles enables running lines even on-street in the suburbs, which is a rather good way to make transit more accessible, but obviously won't work if high capacity is needed. This is why such lines are often "bundled" together in dedicated tunnels in the central parts of these systems.
Few more than some aficionados know that the term S-Bahn was coined as an abbrevation of Stadtschnellbahn (literally a city-rapid-railway) and in direct competition to the U-Bahn in Berlin. Ever since, S-Bahn systems have been created in most German-speaking agglomerations while differing greatly in their network quality.
- Berlin and Hamburg had quite some leeway with already established separate tracks for suburban and national services and could therefore afford an electrification of their suburban rails without taking account for the national services whatsoever, cementing an already divergent development of the two systems and the mutation of suburban rail into a rapid transit system in all but name. Foreign sister systems are the S-tog in Copenhagen (started in 1934) and also Bay Area Rapid Transit (started in 1972).note
- Berlin runs on 750 V DC from a third rail, Hamburg runs on 1200 V DC from a third rail after starting with overhead wire. There are more reasons why the Berlin and Hamburg systems are incompatible with each other.
- Newer S-Bahn networks (i.e. built after World War II) that live up to their names were inaugurated after the construction of a central city underground tunnel connecting to existing railway lines that are supposed to feed the tunnel from opposing ends. Lacking the leeway of Berlin and Hamburg, they will never achieve the same degree of separation as in said two cities. Typically there's been one or two termini in the city and said tunnels made them partial through stations. Foreign sister systems are plentiful in the world, first and foremost the RER in Paris, Crossrail in London and, for the Americans, the Center City Commuter Connection in Philadelphia.
- In Germany, they were typically built in the 1960s and 1970s as in Frankfurt am Main (Rhein-Main network), Stuttgart and Munich; Hamburg received an additional inner-city core route. Their role model was Berlin's north-south link from the 1930s.
- Special mention deserves the recently opened link in Leipzig that went through a 100-year long Development Hell as it already started digging a tunnel in 1913, but World War I brought it to a halt and World War II aborted a renewed attempt, eventually rendered obsolete as the planned route was changed in its course after the war. East Germany lacked the cash to make the link a reality, thus construction only became a reality in The Berlin Republic.
- Many other cities with S-Bahn networks had through stations from the beginning and therefore lacked the necessity, but also the chance, to construct a thoroughly new inner-city link for a suburban railway service. In some areas, an S-Bahn network can even be a merely rebranded regional rail. Needless to say, the standards of the various S-Bahn systems vary a lot. Best way to fetch the details is the Germany folder at urbanrail.net.
- Several other countries have also taken to calling their commuter rail systems S-something and abbreviating them with an S, even though this sometimes makes limited to no sense in the target language.
Similar to The London Underground and the New York City Subway, the U-Bahn Berlin runs with two different profiles. The Kleinprofil (small profile) is the older one dating from before World War I with cars of a width of 2.30 m, accessing third rail from the side. The Großprofil (large profile) is the newer one with cars of a width of 2.65 m, accessing third rail from the bottom. Both systems however run on the same standard gauge of 1435 mm and the same voltage of 750 V DC. The small-profile routes are older, have more complex interworking between lines, and have surprisingly long sections above ground (including a two-level elevated transfer station at Gleisdreieck), whereas the large-profile lines are newer, exist (currently) as separate end-to-end services, and are almost all underground - amusingly the precise reverse of the situation in London. All cars are colored in school bus yellow, the corporate identity color of the BVG, just like all the city's trams and buses.
The S-Bahn cars of Berlin are also very particular. Beside the 3 meter car width and running on 750 V DC from a third rail instead of 15 kV AC from overhead wire as usual in S-Bahn trains elsewhere, they are bicolored in a goldenrod color in the upper half and red in the lower half (instead of just red).
The Berlin U-Bahn is an open system (i.e. no turnstiles) running from 5:00 to 1:00 every day and 24 hours on Friday and Saturday nights. It runs every 4-5 minutes at rush hour, 5-10 minutes off-peak and 15 minutes at nights when it runs. The S-Bahn Berlin runs from 4:00 to 1:00 and doesn't run a comparable night service to the U-Bahn's.
But even in the nights when rapid transit won't run, you can easily get by and around in most parts of Berlin via nightline buses (one-digited ones replace daytime subway equivalents) and the so-called "Metronetz" where buses and even trams run 24/7 on designated routes where they're supposed to offer rapid transit quality service where there isn't any.
For transportation purposes, Berlin and Brandenburg formed the VBB, their one and only transport association. The Berlin system in particular is divided into the three fare zones A, B and C. A is Berlin inside the Ringbahn (roughly "circle line"), B is Berlin outside it and C is for extensions into neighboring Brandenburg, primarily with the S-Bahn. Tickets are always offered for two zones at least, either AB, BC or ABC respectively. A one-way ticket e.g. would cost you 2.80 in AB, 3.10 in BC and 3.40 in ABC.
At the turn to the 20th century, Berlin like so many other cities had to deal with traffic problems. In 1902, the first line of the so called Hoch- und Untergrundbahn run by the private Hochbahngesellschaft (Elevated Rail Corporation) was put into service. Actually, Siemens & Halske initially had their plans rejected and first put them into fruition in Budapest as a showcase. And as the name suggests, it wasn't completely underground, but rather elevated in (pre-1920 borders) Berlin with the exception of a stub to Potsdamer Platz and underground in the affluent Charlottenburg. Berlin was actually scared that an underground would hurt the recently built canals.
Until the start of World War I, the 2.30 m profile network of the Hochbahngesellschaft had three branches in the west (into Charlottenburg, Wilmersdorf/Dahlem and Schöneberg, lines later denoted with Roman numerals) and two in the east (Pankow via Mitte and Friedrichshain via Kreuzberg, becoming A and B respectively), today they're the lines U1 to U4.
After said war and the expansion of Berlin in 1920, all new lines would be built to a 2.65 m profile. In the Weimar Republic, this would be the public Nordsüd-U-Bahn (later line C, today U6 and parts of U7), the GN-Bahn made by the AEG (later line D, today U8) and the line E (today U5) into eastern Berlin. After the BVG was established in 1929, the Hoch- und Untergrundbahn was shortened to the nice and perky U-Bahn, becoming the German catch-all term for underground, subway, metro, you name it.
Evolution of suburban rail into the S-Bahn
With the introduction of railways, the Prussian capital and primate city Berlin quickly had to deal with the consequences of congestion on its isolated rail lines that ended in several termini.
- To connect Berlin's various termini via then unsettled hinterland, the Ringbahn (ring/circle rail) was built and opened in 1871. Berlin would only later grow into the ring to make it an urban artery. It's dubbed Hundekopf (dog's head) due to its form and became an important technical boundary; beside being the outer limit of fare zone A and having an autobahn around half of it, it's also an official no-go area for dirty diesel cars.
- For a more passenger-oriented transfer possibility, the elevated, east-west running Stadtbahn (city rail) was built and opened in 1882, starting at Charlottenburg Station in the west and ending at Silesian Station (now East Station) in the east, both former termini. It was built from the start with separate double tracks for suburban and long-distance traffic. The system of Berlin's so-called Ring- und Vorortbahnen was then complete and became the Stadt-, Ring- und Vorortbahnen.
- Between 1890 and the turn of the century, the congested Vorortbahnen (suburban rail) and the Ringbahn got second sets of double tracks for a similar functional separation. A special fare system was introduced by 1891.
The essentials for the later network were therefore laid a good 30 years before the official "birthdate" of the S-Bahn that's usually set in 1924 when the very first electrified single connection from Stettiner Bahnhof (today Nordbahnhof) to Bernau went online. Electrification became an issue right after World War I as the original fleet of steam trains was about to be retired anyway. AC was not yet as well developed as DC which, together with third rail, had already proved itself in the U-Bahn and was therefore adopted for the new S-Bahn.
- In 1924-30, the whole system underwent third rail electrification on par with the U-Bahn. On December 1, 1930, the system got rebranded as Stadtschnellbahn (city rapid railway) or S-Bahn for short, the mother of all other systems. The last tracks to Wannsee were converted in 1933.
- In 1934-39, the third and last of the S-Bahn core lines was built, the north-south running Nordsüd-S-Bahn-Tunnel or Nord-Süd-Tunnel in modern parlance, the only underground section of the whole system. Part of it had already been opened in 1936 for the Olympic Games, the rest was only put into service right after the invasion of Poland.
The network as we know it today was therefore complete by the start of World War II.
Needless to say, the division of Berlin seriously affected its infrastructure. From now on, West and East Berlin would diverge in their development. The BVG quickly divided into the BVG (West) and BVB (East).
Rail traffic plummeted as the old capital of Prussia and the Reich became a torso of its former self and as formerly centrally located termini became part of a frontier over night, they either became undemanded, undesired or both. The result was that all the termini in Berlin were laid off by 1952. The vital post-war stations were concentrated along the Stadtbahn, of course: In West Berlin, Zoo Station became the de facto main station, whereas in East Berlin there was the East Station to fulfil said role until eventually being outperformed by Berlin Lichtenberg Station that's even further to the east. note
Most important were two new lines: The north-south running line G (U9) opened quickly after the wall was erected and the southeastern line C I was expanded to become line H (U7) and came to thoroughly criss-cross West Berlin. Pre-war lines C (U6) and D (U8) were also extended, but they became more prominent for their middle sections becoming quintessential Sinister Subway lines. East Berlin stations of said lines were closed for the public and protected by armed guards and state security that became Geisterbahnhöfe, "ghost stations" or "haunted stations".
In 1958, West Berlin ceased to use its "letter + roman numeral" designation system for U-Bahn lines as they started to confuse the passengers, especially as the unbundling of the small profile lines led to designations up to "B IV". From now on, the letter designations have been used for internal purposes only and the lines were named for their mere termini. After the unbundling of the C lines in 1966, West Berlin introduced Arabic numerals to designate its lines, following the role model of Le Métropolitain. East Berlin only had two U-Bahn lines and therefore lacked the West's urgent need to seek clarity.
West Berlin swam in money due to federal subsidies and there was a broad consensus among all relevant political groups that U-Bahn extensions were desirable, so a lot of U-Bahn was built in that era, while plans were drawn up for further extensions that would make sense upon reunification or the construction of other extensions. As Berlin's financial situation has markedly deteriorated since 1990 and the U-Bahn extension consensus has evaporated, many of those extensions are now stuck in Development Hell.
In the very end, the East Berlin line E (modern U5) was intended to receive a Western sister to access Tegel Airport (now closed in 2020 for BER to open) to be merged through Central Berlin after reunification. Before that, a line U10 (formerly F) along the Wannseebahn was scheduled to be built from 1985 onwards, but quickly dropped when control of the Western S-Bahn was finally handed over. The reasons for this were, as usual, complicated.
The GDR already wanted to lease the S-Bahn in West Berlin to the BVG in the 1970s as the obligatory presence of the DR in West Berlin per Allied treaty proved to be expensive due to the boycott, but this offer was denied as West Berlin argued that it didn't belong to the DR, but the DR rather possessed mere operation rights. The S-Bahn continued to deteriorate without any attention, but this changed dramatically when the remaining employees for the DR in the West struck in 1980.
The strike was quickly put down by Soviet authorities, but after widespread resignations from and dismissals by the DR and a drastic reduction of the schedule, West Berlin started to bother about what was left of the S-Bahn. It also helped that a political scandal rocked Berlin and led to snap elections in 1981. The conservative CDU under Richard von Weizsäcker won in a landslide, but failed to gain an absolute majority and formed a minority government whose support also depended on some rogue delegates from the liberal FDP. note
On October 31, 1983, after the Allied powers and both German governments greenlighted a desired transfer, negotiations between the GDR-owned DR and the Senate of Berlin started and finished after two months; transfer of operation rights happened on January 9, 1984. Needless to say, a lot of renewal construction had to be done. They also attempted to change the livery of the trains to blue, but a massive public backlash forced them to go back to the traditional red and yellow.
On a smaller note, overtaking the S-Bahn led to changes in line designations. Under DR legacy, S-Bahn lines were denoted with letters and numbers, Roman and Arabic alike, in differing combinations, though they were mostly known for their termini. Now the BVG, as the West Berlin transport authority, followed the precedent of other West German S-Bahn networks and labeled them as "S" + "number". The merely numbered U-Bahn lines have therefore been labeled "U" + "number" ever since.
But just as the West, the East also had plans for new stretches of U-Bahn, the only difference is that the East couldn't afford it. The easternmost part of line F (Alexanderplatz - Weißensee) was scheduled to be built in the early 1970s and the GDR actually did precautions when it remodeled Alexanderplatz in the late 1960s, but eventually came to the conclusion that the country lacked the money to make it reality.
Another brainchild of the GDR was a new U-Bahn line that current urban planning has designated as a line U11 along Mollstraße and Landsberger Straße. The GDR also wanted to reactivate lines C and D on its East Berlin stretches, cutting off their West Berlin ends from each other, but then the GDR died years before any efforts could come into fruition.
Not too much later, Germany reunited in the same year. The co-reign of BVG and DR over the Berlin S-Bahn only ended with the start of 1994, when the old DB and the DR were united into the Deutsche Bahn AG or DB for short. A year later, the reformed DB created the S-Bahn Berlin GmbH as a limited liability company for S-Bahn operation.
Since then, Berlin worked hard to extend minor stretches of U-Bahn to create useful links to the S-Bahn. And the S-Bahn of Berlin would now get thoroughly rebuilt with Western money. All main routes needed to be renewed to achieve the desire to rebuild the S-Bahn network to the quantity and quality of 1961, i.e. before the Berlin Wall. This was not achieved until 2002 when the Ringbahn was completely reopened again. The U-Bahn was considered re-unified in 1993 when East Berlin line A (U2) was reconnected to the remainder of the small profile network, discounting the 1995 reopening of Warschauer Brücke station after the reconstruction of the Oberbaum Bridge.
After Hole in Flag reunited Germany and said Germany decided to make its old new capital live up to its name, Berlin turned into Europe's biggest construction site. On the other hand, Berlin gradually lost the special contributions it received from the federal government it got during the Cold War and which made up about half of its budget. Berlin from now on was integrated into Germany's inter-state fiscal adjustment and while this particular city-state profits most from it, it still feels the pain from adjusting from XXL to XL size. Especially after a banking scandal rocked the city in 2001, the budget situation has been abysmal.
First of all, it was decided to build a new central station at the site of old Lehrter Bahnhof. Berlin Hauptbahnhof was indeed opened in 2006, complete with a new railway tunnel crossing the Stadtbahn at said place. Like a modern airport, it's also built to be a giant shopping mall and it's speculated that's why the DB cancelled Zoo Station for its national train services as it helps feed the shopping mall with costumers that otherwise would rather have boarded and disembarked at well-connected Zoo Station. East Station has been spared from a similar fate and most often makes the last stop for trains ending in Berlin.
But the new Berlin railway node is far from complete. As the S-Bahn in Berlin needs separate tracks from the mainline railways for reasons already mentioned, another north-south tunnel is currently under construction and its northern half scheduled to open in the 2020s, the project's name is S21. It actually re-uses shell constructions near Potsdamer Platz for similar plans made by the Nazis for a second north-south S-Bahn link. A tramlink from the east via Invalidenstraße reached Hauptbahnhof in 2014 and has seen service by three lines since 2015. Further extension of said tram line westward is currently (2018) planned.
The Kanzler-U-Bahn (Chancellor Subway)
The extension of the U5 from Alexanderplatz to Berlin Central Station via the historic centre of Berlin is currently undergoing and supposed to be finished by 2020. A short stretch has already been opened between Central Station and Brandenburg Gate as an isolated stub called U55, because the city would have had to pay back money to the federal government if they hadn't opened some kind of service within a certain time limit.
It's been dubbed Kanzler-U-Bahn (Chancellor Subway) as it runs under the new and old government quarters created near the Spreebogen and its construction has been part of a so-called "Capital Treaty" determining the guidelines to make Berlin fit as a capital. The chancellor in question is Helmut Kohl, who lost reelection in 1998, a year ahead of the Bundestag actually moving to Berlin and died in 2017, long before the full length U5 was to open.
Berlin At Day And Night: The Ascence Of Captain Ersatz
Under the impression of the rush after the fall of the wall, the BVG started subway night line services in April 1990. Two selected lines crossing at Zoologischer Garten would from now on be served every 15 minutes in nights preceding workfree days.
- The north-south running U9 as a backbone of West Berlin and quickest way from East to West until broken lines were mended.note
- The west-east running U1 (later U12 and eventually disbanded) from Ruhleben at the edge of Spandau to Kreuzberg ending at the Spree River.
- Finally in June 2003, the night grid was extended to most other subway lines, albeit with occasionally shorter routes. Notably lacking services in the night grid are U4 (stub line in Schöneberg), U55 (even shorter stub line and Butt-Monkey of the republic) and the westernmost ends of U2 (Theodor-Heuss-Paltz), U3 (Thielplatz, near the Free University) and U7 (Jakob-Kaiser-Platz).
From December 2004, Captain Ersatz has reigned supreme with qualified bus and tramway services introduced as a so-called "metro network" or Metronetz with the products Metrobus and Metrotram. They're supposed to serve vital lines inside of Berlin that would theoretically deserve accessibility by rapid transit where there isn't any and from 2006, they've offered 24/7 services ever since.
A Modern Disaster Area: Chaos In The S-Bahn
From winter 2008/09 onward, the S-Bahn Berlin has experienced its worst crisis since the 1980 strike. Maintenance was neglected as Deutsche Bahn tried to save costs on the wrong end to look good for a planned float on the stock market that eventually got scrapped due to the ongoing economic crisis, said neglect got so bad that the federal railway agency made the unprecedented move to forcibly lay up a good chunk of the S-Bahn vehicle fleet. Contemporary witnesses are even quoted to say that the S-Bahn even ran better right after the war! Return to normalcy in operations is estimated to return in 2013.
The current contract between the city-state of Berlin and the DB will end with the schedule change of December 2017. To get the S-Bahn back on feet, Berlin wants to get serious about competition in its EU-wide call for bids that otherwise often end with the DB becoming the only bidder. Berlin divided its S-Bahn network into three parts (corresponding to its three core stretches) for this recent call of bids, starting the biggest part with the Ringbahn and the adjacent Görlitzer Bahn. Interested bidders came as far as from Britain, France and even China. There was some initial reluctance on the left side of the political spectre, rather condemning attempts for a "partial privatization" of public services, but the BVG rejected demands to take over the S-Bahn like it had under other political circumstances and it's not like the DB had acted like a bona fide public service provider.
The East actually wasn't that eager about its streetcars either and got them rid from Alexanderplatz by 1967, but the economic necessities in an underperforming socialist economy stopped the East from the car-oriented anti-tram frenzy that's been seen in the West. With the advent of Czechoslovak Tatra vehicles, the tramway once again became a modern mode of transport again and the desire to replace tram tracks with subways became less urgent and new extensions were built to access new housing projects.
When reunification came along, car-oriented urban planning already had experienced a major backlash and what happened now was a tram reconquista. The first and major extension into former West Berlin was built from Prenzlauer Berg via Gesundbrunnen into Wedding, all quite populous and accessing five rapid transit lines on the way. The second "western" extension was a relatively short but useful line along Bernauer Straße, a street in former West Berlin running parallel to the northern boundary of East Berlin precinct Mitte (Centre) and therefore directly on the western side of the wall. The third extension was the much delayed extension of trams along Invalidenstraße to Berlin Hauptbahnhof, which finally opened in late summer 2015 and significantly improved the ease of getting to other parts of the city from the station.
The Red-Red-Green coalition government (leftist/center-left) in office since 2016 has committed to further tram extensions at the expense of any further U-Bahn construction, much to the chagrin of the opposition parties of CDU, FDP and AfD which considers U-Bahn extensions vastly preferable to trams.
- U1: Color green. All iterations of line 1 were based on the former line B on the eastern stretches of the former Stammstrecke. In its modern iteration, it equals the course of the U15 in service for this first couple of years after Reunification. From 1961 to 1995, the eastern terminal Warschauer Straße was closed as it was its only station in East Berlin and the war-torn Oberbaum Bridge needed to be thoroughly rebuilt again.
- U12: The U12 is an episodic auxillary line that served as a festival and night line in 1993-2003 and gets reactivated whenever central portions of either U1 or U2 are broken to lower the number of transfers for normally not transfering passengers from two transfers to merely one. It actually matches the course of the line 1 from 1961 to 1993, fusing BI and AI, the latter now again part of the U2, the original line A.
- U15: The U15 was in service in 1993-2005 as an extension of the "old U3", formerly line BIV, a small stub line into Charlottenburg, into the eastern Stammstrecke. The stub was the result of a political horse trade wherein Charlottenburg reluctantly agreed to allow parts of a more important subway line (the modern U3) into rivaling Wilmersdorf to be built on its territory.
- U2: Color red. Started as the first truely underground subway section into Central Berlin from the western portions of the original Stammstrecke to form line A. Cut in half during the division of Berlin, its central overground section to the west of the Berlin Wall deteriorating and built over with a little maglev (the M-Bahn) shortly before Hole in Flag and disassembled just as quickly (1991) as it was assembled (1987). After 1966 until 1993, the line 2 or U2 used to be the name of what is now the U3.
- U3: Color lime green. Running all the way from Wittenbergplatz into the deep southwest of Berlin, the former lines AII and BII ran along the course that is now served by the U3. After unbundling, it's been internally dubbed as AII and also got the line number 2 after 1966, supposed to be merged with the line A in East Berlin one day, therefore following chronological order both in all of Berlin and West Berlin alone. After the central section of the modern U2 was rebuilt in 1993 and several lines were recombined, what is now the U3 became part of the U1. From 2005 on, Wittenbergplatz-Krumme Lanke became the U3. Besides serving many posh boroughs of Berlin, it also accesses the Free University of Berlin, one of the three Berlin universities besides the old Humboldt University and the Technological University. From May 2018 on, line U3 will be extended to Warschauer Straße and run the same course as the U1 did in 1993-2005.
- U4: Color yellow. A short five-stop line running entirely in Schöneberg which used to be an independent city when it decided to build the very first publically owned subway in Germany after the Hochbahngesellschaft deemed such a line not to be profitable enough. It already went online in 1910 and got the designation BIII when it was integrated into the Berlin network. It has not been extended since its first construction and there have not been any serious plans to do so. On one end it is "boxed in" by the city Autobahn, which would require pretty deep tunneling and on the other it ends near downtown where a number of subway lines already go. It is the only line besides U55 not to have any type of night service.
Large profile lines
- U5: Color brown. A small stub line in Charlottenburg labeled AIII was shortly the line 5, but was closed in 1970 and the number 5 was reserved for the line E in East Berlin that was built in 1930 from Alexanderplatz to Friedrichsfelde. It got a minor extension to Tierpark (East Berlin Zoo) in 1973 and a major extension into new housing projects in 1988/89. Currenctly, the middle section of an extension from Alexanderplatz to Berlin Central Station are underway. Theoretically, it should one day be continued to what is now Tegel Airport, but as said airport has been closed for BER Airport in Schönefeld and as Berlin is bankrupt, it will likely remain theory.
- U55: Opened in 2009, the U55 is an isolated stub of the U5 shuttling between Central Station and Brandenburg Gate. An alibi service in order to not pay back federal grants. Work to connect U55 to U5 (and getting rid of the U55 name afterwards) is underway. The current rolling stock of U55 had to be lowered in from above through a hole specifically left for that purpose as there is no rail connection to any other part of the network. The stations have also been used to shoot some movies before service started, among them Æon Flux.
- U6: Color violet. With core sections built from 1912 on and completed in 1923, post-war extensions completed the line until 1966. Originally called the Nordsüd-Bahn due to its major direction, it was Berlin's first publically built subway line, also featuring the larger profile for the first time ever. Traditionally called line C and retaining the CII bifurcation after it finally split. Passed through East Berlin without stops expect for Bahnhof Friedrichstraße in 1961-89/90, being a border checkpoint during the city's division. In the course of the U5 extension there'll be a new transfer station Unter den Linden while the U6 station "Französische Straße" will be shut due to being too close to the new station.
- U7: Color light blue. Originally line CI and therefore considered the integral part of the Nordsüd-Bahn, first stretches were opened in 1924. After the war, the desire to unbundle bifurcations led to the re-conception of line CI into a southeast-northwest line H. After a one-stop extension and especially the reconstruction of Mehringdamm station from a bifurcation station to a transfer station, the C/CII tracks and the CI/H tracks got reopened as lines 6 and 7 in March 1966, introducing Arabic numerals for the U-Bahn lines. This was just an intermediate step, however, and the new line 7 was to see four major extensions in its west making it symptomatic for its Cold War nature.
- In 1971, line 7 was extended up to Fehrbelliner Platz, crossing as many other lines as possible and making for a direct connection between Neukölln and City West, the CBD of West Berlin.
- Until 1972, the southeastern extension of line 7 to Rudow was completed, connecting the housing project "Gropiusstadt" to the network and also featuring the newest depot of the Berlin U-Bahn.
- Until 1978, a northwestern extension through Charlottenburg via Adenauerplatz (western end of the Ku'damm) to Richard-Wagner-Platz (near Charlottenburg City Hall) was constructed. (The station at Richard-Wagner-Platz existed before, having originally been on a short spur of U2.) Up to here, the route follows plans for a new circle line of the U-Bahn envisioned in the Albert Speer's Germania plans, a circle line for the U-Bahn inside the circle line of the S-Bahn which made the purpose of the line 7 fully clear: Providing an alternative to the S-Bahn.
- In 1980, line 7 was extentended via Jungfernheide to Rohrdamm, accessing the Siemens works in Berlin. Some days before, the strike at the DR essentially castrated the S-Bahn in West Berlin and turned the line into a necessity.
- In 1984, the U7 as it's been called now was extended to Spandau City Hall, bearing its total modern length and making it the world's longest tunnel until 1988 when the Seikan tunnel opened. It thus reached its current length and remains the longest line in the system, which does not stop expansion talks, however.
- Rudow as the line's southeastern terminus is not all that far from Schönefeld Airport (and there is already a bus linking the two points) and Berlin Brandenburg Airport would have its main terminal just a kilometer from there, so you can make a great case for extending the line there. The actual underground railroad station that sees passenger-free maintaining traffic to prevent mold from growing is for the S-Bahn, lines S9 and S45 to be exact. Extending line U7 was rejected for only benefiting the borough of Neukölln where the U7 runs. However, in the course of the keep-Tegel-open referendum (which passed but is non-binding) renewed talks of extending U7 to Schönefeld and perhaps further to the new airport came up. A problem with such an extension would be how construction and operating costs are partitioned between Berlin and the neighboring municipality Schönefeld in Landkreis Dahme-Spreewald (LDS for short and on car plates), Brandenburg. A similar problem was also the reason why parts of Honöw became incorporated into Berlin upon reunification.
- In 1971, line 7 was extended up to Fehrbelliner Platz, crossing as many other lines as possible and making for a direct connection between Neukölln and City West, the CBD of West Berlin.
- U8: Color blue. Initially called GN-Bahn as it runs from Gesundbrunnen to Neukölln, later line D. Initially built by the AEG and completed by the city of Berlin after the former's subsidiary went bankrupt and after it had its other subway done. First stretches were opened in 1927 and the initial core line was completed in 1930. Featured many ghosts stations in East Berlin that by now are under monumental protection for their 1920s style and experienced generous northward extension in the 1980s. Its southern terminus Hermannstraße served as an airraid shelter in World War II and traces of it were consciously worked into the final station design that was in all aspect two generations late. Its northern part was generously extended in West Berlin for eventually accessing Märkisches Viertel which has yet to be connected.
- U9: Color orange. Built after the war as a bypass around East Berlin, accessing City West from the north and south. 20 days before it was supposed to open, the Berlin Wall was erected and the opening was preponed by five days. Considered the fastest of all U-Bahn lines in Berlin and also the first one to offer night services. Extensions into both directions beyond its current scope have been planned since its inception: Down south to Lankwitz and up north into Pankow in former East Berlin, also requiring a one-stop extension of the local U2 for providing a transfer station.
- U10: Color black considered, formerly line F. In its historic conception, you could divide into the phases.
- The maiden stretch Alexanderplatz - Weißensee was conceived in the 1920s and is part of all iterations. Alexanderplatz station was actually built in a way that one platform level would fit two east-west lines, the existing U5 on its inner tracks and the hypothetical U10/U3 on its outer tracks.
- The central section Alexanderplatz - Kleistpark via Potsdamer Platz was originally planned as a westward extension of line E before World War II, but was quickly realigned to line F after the war and matched better to a clear direction.
- The southwestern section (Steglitz - Kleistpark) was deliberately planned as a Department of Redundancy Department to the Wannseebahn serviced by the S-Bahn and therefore very vulnerable to any minor form of The Great Politics Mess-Up.
- Nowadays the southwestern section is considered obsolete while the eastern section from Potsdamer Platz via Alexanderplatz to Weissensee (and even further) is still planned and a western extension would integrate a reconstructed version of the "old" U3 or former B IV (see U15), the line would eventually also be labeled as U3 should it ever go online, the "current" U3 getting recombined with the U1.
- Students from the TU Berlin proposed a realization of the Cold-War link as a tram connection that isn't supposed to replace the S-Bahn, but rather to replace the current overcrowded bus service, most likely as an extended line M4.
- U11: As mentioned, a mind child of the GDR and officially planned, but far from realization, also due to excellent tram services on its route which have been extended to Central Station just as said U-Bahn is supposed to be. The 2016 red-red-green coalition treaty also plans to extend the tram line even further, possibly to the site now occupied by Tegel Airport (possibly already put to another use by then).
(N/S = Nord-Süd-S-Bahn-Tunnel; SB = Stadtbahn)
- N/S tunnel lines (Bornholmer Straße - Gesundbrunnen - Friedrichstraße - Potsdamer Platz - Yorckstraße (- Schöneberg) - Südkreuz)
- S1: Wannsee - N/S - Frohnau - Oranienburg
- S2: Blankenfelde - Lichtenrade - N/S - Buch - Bernau
- S25: Henningsdorf - N/S - Teltow
- S21: As of 2017, construction is underway to connect Hauptbahnhof (Berlin Central Station) to the ring along a new north-south spine. The line is tentatively named S21 and will connect Hauptbahnhof to Südkreuz in the South and Westhafen / Wedding in the north (with onward connection along the ring to Gesundbrunnen, the "missing" Nordkreuz).
- Stadtbahn lines (Westkreuz - Charlottenburg - Zoologischer Garten - Berlin Central Station - Friedrichstraße - Alexanderplatz - Berlin East Station - Ostkreuz - Lichtenberg)
- S3: Westkreuz - SB - Erkner
- S5: Spandau - SB - Mahlsdorf - Stausberg (- Strausberg Nord)
- S7: Potsdam - Wannsee - SB - Ahrensfelde
- S75: SB from Ostbahnhof - Lichtenberg - Wartenberg
- Ringbahn lines
- S41 and S42 are full circle lines in opposing directions.
- S45, S46 and S47 connect the southern Ringbahn with the Görlitzer Bahn.
- S6: Buch - Pankow - Ostkreuz - Grünau, to be introduced in 2020
- S8: Birkenwerder - Pankow - Ostkreuz - Grünau (- Zeuthen)
- S85: Waidmannslust - Ostkreuz - Schönweide (- Grünau)
- S9: Pankow - Ostkreuz - Schönefeld Airport
- S6: There's an idea to connect the northern S21 with the Görlitzer Bahn through a new trunk line in Kreuzberg planned in the 1920s as an U-Bahn and in the 1930s as the Ost-West-S-Bahn, making for a direct connection from Gartenfeld at a rejuvenated Siemensbahn in the northwest to the Berlin Brandenburg Airport in the southeast. There would be five new stations between Potsdamer Platz and Plänterwald all offering interchanges.
As such, reunified Berlin has built less new U-Bahn kilometers in almost thirty years than East Berlin had in the 1980s. While the network still hasn't reached the length of 200 km envisioned during the era of Ernst Reuter, U-Bahn extensions have become a political football and classical "Sommerloch"note issue.
It is pretty obvious that Berlin cannot afford to build more than a few stations at a time and likely not on more than one line at once. However, aside from the under construction U5 extension which was called for by federal law, there are few extensions that are eminently better than others at first sight and the governing (elected 2016) red-red-green coalition has said they won't move forward on any proposed expansions before 2021. The tram and S-Bahn are different stories and extensions are either underway or planned for the foreseeable future. That said, here are some of the extensions that are repeated every time the debate comes up:
- U2 to Spandau - preparatory works for such a line exist, but it is unclear whether extending the line beyond Spandau (the original purpose of those plans) would be doable with the current budget. Tram reconquista is an often-proposed alternative as are S-Bahn reactivations.
- U5 via Turmstraße and Jungfernheide to Tegel Airport - officially still planned, unlikely to happen before Tegel Airport closes, currently not a priority.
- U7 to the new Berlin Brandenburg Airport - would link Neukölln to the airport on a more direct route than the S-Bahn and expand the U-Bahn outside the city boundaries for the first time since Hönow (U5) was annexed; downsides are the sparse population in Schönefeld (necessitating a few kilometers of subway through areas where few people live) and the lack of any preparatory works under the new airport terminal.
- U8 to Märkisches Viertel - only a short stretch would be needed and Märkische Viertel was built in such a way as to allow easy subway construction. However, the last few stations of U8 are little used as it runs in parallel to the S-Bahn due to being planned in the 1980s and getting built anyway. An extension of the tram from Pankow is often discussed as a potential alternative.
Berlin U-Bahn and S-Bahn sub-tropes
- The Alleged Car
- The DR 170 series has been called "the blue miracle" (read: shock of your life) for a reason. It's been in blue and full of technical problems. They could have been fixed and become the first post-war S-Bahn stock, but demand for it plummeted due to the boycott in the West and the repurchase of old S-Bahn trains that used to be reparations to the Soviets. A very unique kind of The Great Politics Mess-Up.
- The BVG E series were reconverted railway trains for use on the only East Berlin large profil line E. They fell into disuse after reunification.
- Balkanize Me: Berlin as the most prominent divided city is a showcase, of course.
- Demoted to Extra: Berlin serves as a very empiric example of what's been written at the trope page about what happens to older vehicles when new ones come along.
- The two Sinister Subway lines of the Cold War were run with the oldest trains as they had rather little clientele and it was feared that they could be abducted into East Berlin (via tunnel near Alex).
- West Berlin also used to help out East Berlin by selling them old cars that would otherwise have been wrecked.
- D series have been completely retired in Berlin but run in Pyongyang and a small profile sister series is still running until substitution by the new IK class coming in 2014.
- Dummied Out: Even more so than in other cities in the world due to historic legacy.
- The Great Politics Mess-Up: No city in the world has its historic legacy as thoroughly cast into concrete as Berlin has. The Cold War got an own folder in this article for a reason.
- I Call It "Vera": The U-Bahn's trains of the D series are called (Stahl-)Dora and those of the G series are called Gisela and both spend (D) or used to spend (G) their twilight years in North Korea.
- Missing Floor: The aforementioned ghost stations.
- Overly Narrow Superlative: Berlin has at least the biggest U-Bahn in Germany. The Métro Paris may be bigger than the U-Bahn Berlin and the RER d'Île de France may be bigger than the S-Bahn Berlin as well, but as the RER isn't separate from other railway traffic unlike the S-Bahn Berlin, Berlin still had the biggest total rapid transit passenger route length in the world before the systems in Beijing and Shanghai eventually overtook it. On the other hand, Berlin doesn't have the biggest mere S-Bahn network of Germany at all, but rather lies in the middle of the top ten. However, Berlin and Hamburg are the only cities with a third rail based S-Bahn and what is considered "S-Bahn" in some cities would probably be called "Regionalbahn" in Berlin.
- Sinister Subway: Due to the Berlin Wall, making it its essential Trope Codifier. Two U-Bahn and one S-Bahn lines ran in transit from West via East into West again and their eastern stations were closed and became Geisterbahnhöfe. Check out Potsdamer Platz.
- Subways Suck: Not so much the U-Bahn, but rather the S-Bahn at times. Especially when the S-Bahn deteriorated in the West. And when the Deutsche Bahn tried to save money at the wrong ends for a flotation.
- Suspiciously Similar Substitute: Subways and busses were supposed to replace trams/streetcars and GDR-run suburban rail, so don't be too surprised to find eerily similar courses of bus lines vis-à-vis former tram lines or, as an Inverted Trope, concepts of new tram lines both designed to get rid of the busses and as an alternative to long-planned U-Bahn lines running the same course. Examples include...
- U5: Westward extension beyond Central Station is unrealistic and tram reconquista is supposed to be a better alternative.
- U7: The post-war extensions can be divided into two segments: One designed as part of a never realized circle line planned by Albert Speer for Germania and a part that matches nicely with the very last delayed tram line from Charlottenburg to Spandau. And both rendered large chuncks of the S-Bahn obsolete.
- U9: This line was originally supposed to extend into Pankow in former East Berlin after the end of the Berlin Wall, but then trams tracks from Prenzlauer Berg to Wedding have been built that closed the gap.
- U10: A major candidate for tram reconquista.
- U11: The tram reconquista to Berlin Central Station is underway.
- They Changed It, Now It Sucks!: As mentioned, they failed to introduce blue S-Bahn cars in West Berlin.
- Vestigial Empire: Berlin before 1945 was known to have a role model railway network that got broken due to the circumstances created by the Cold War.
- Among the core lines, only the east-west Stadtbahn never changed its purpose and was in fact the only common thread between the two halves of Berlin when it was divided and has featured all the important mainline stations ever since.
- The N/S tunnel may have been built as a complement to the Stadtbahn, but also connected the two most important termini of Berlin, the northern Stettiner Bahnhof and the southern Anhalter Bahnhof, to the most central Bahnhof Friedrichstraße that would later serve as a border checkpoint and only accesible station in an otherwise Sinister Subway.
- The circular Ringbahn is the oldest of them all and was built through the at-the-date outback of the Berlin conurbation to connect the termini to one another and simply existed when the conurbation grew into it. It's not exclusively suburban rail and especially its north is vital in accessing a new N/S mainline tunnel that serves Berlin Central Station (at old terminus Lehrter Bahnhof) where it crosses the Stadtbahn, but its major purpose was and is suburban rail.