Berlin is the capital and largest city of Germany by both area and population. Its 3,748,148 inhabitants make it the second most populous city proper of the European Union after London; the city is one of Germany's 16 federal states. It is surrounded by the state of Brandenburg, contiguous with its capital, Potsdam; the two cities are at the center of the Berlin-Brandenburg capital region, which is, with about six million inhabitants and an area of more than 30,000 km², Germany's third-largest metropolitan region after the Rhine-Ruhr and Rhine-Main regions. Berlin straddles the banks of the River Spree, which flows into the River Havel in the western borough of Spandau. Among the city's main topographical features are the many lakes in the western and southeastern boroughs formed by the Spree and Dahme rivers. Due to its location in the European Plain, Berlin is influenced by a temperate seasonal climate. About one-third of the city's area is composed of forests, gardens, rivers and lakes; the city lies in the Central German dialect area, the Berlin dialect being a variant of the Lusatian-New Marchian dialects.
First documented in the 13th century and situated at the crossing of two important historic trade routes, Berlin became the capital of the Margraviate of Brandenburg, the Kingdom of Prussia, the German Empire, the Weimar Republic, the Third Reich. Berlin in the 1920s was the third largest municipality in the world. After World War II and its subsequent occupation by the victorious countries, the city was divided. East Berlin was declared capital of East Germany. Following German reunification in 1990, Berlin once again became the capital of all of Germany. Berlin is a world city of culture, politics and science, its economy is based on high-tech firms and the service sector, encompassing a diverse range of creative industries, research facilities, media corporations and convention venues. Berlin serves as a continental hub for air and rail traffic and has a complex public transportation network; the metropolis is a popular tourist destination. Significant industries include IT, biomedical engineering, clean tech, biotechnology and electronics.
Berlin is home to world-renowned universities, orchestras and entertainment venues, is host to many sporting events. Its Zoological Garden is one of the most popular worldwide. With the world's oldest large-scale movie studio complex, Berlin is an popular location for international film productions; the city is well known for its festivals, diverse architecture, contemporary arts and a high quality of living. Since the 2000s Berlin has seen the emergence of a cosmopolitan entrepreneurial scene. Berlin lies in northeastern Germany, east of the River Saale, that once constituted, together with the River Elbe, the eastern border of the Frankish Realm. While the Frankish Realm was inhabited by Germanic tribes like the Franks and the Saxons, the regions east of the border rivers were inhabited by Slavic tribes; this is why most of the villages in northeastern Germany bear Slavic-derived names. Typical Germanised place name suffixes of Slavic origin are -ow, -itz, -vitz, -witz, -itzsch and -in, prefixes are Windisch and Wendisch.
The name Berlin has its roots in the language of West Slavic inhabitants of the area of today's Berlin, may be related to the Old Polabian stem berl-/birl-. Since the Ber- at the beginning sounds like the German word Bär, a bear appears in the coat of arms of the city, it is therefore a canting arm. Of Berlin's twelve boroughs, five bear a Slavic-derived name: Pankow, Steglitz-Zehlendorf, Marzahn-Hellersdorf, Treptow-Köpenick and Spandau. Of its ninety-six neighborhoods, twenty-two bear a Slavic-derived name: Altglienicke, Alt-Treptow, Buch, Gatow, Kladow, Köpenick, Lankwitz, Lübars, Marzahn, Prenzlauer Berg, Schmöckwitz, Stadtrandsiedlung Malchow, Steglitz and Zehlendorf; the neighborhood of Moabit bears a French-derived name, Französisch Buchholz is named after the Huguenots. The earliest evidence of settlements in the area of today's Berlin are a wooden beam dated from 1192, remnants of a house foundation dated to 1174, found in excavations in Berlin Mitte; the first written records of towns in the area of present-day Berlin date from the late 12th century.
Spandau is first mentioned in 1197 and Köpenick in 1209, although these areas did not join Berlin until 1920. The central part of Berlin can be traced back to two towns. Cölln on the Fischerinsel is first mentioned in a 1237 document, Berlin, across the Spree in what is now called the Nikolaiviertel, is referenced in a document from 1244. 1237 is considered the founding date of the city. The two towns over time formed close economic and social ties, profited from the staple right on the two important trade routes Via Imperii and from Bruges to Novgorod. In 1307, they formed an alliance with a common external policy, their internal administrations still being separated. In 1415, Frederick I became the elector of the Margraviate of Brandenburg, which he ruled until 1440. During the 15th century, his successors established Berlin-Cölln as capital of the margraviate, subsequent members of the Hohenzol
The Berliner Verkehrsbetriebe is the main public transport company of Berlin, the capital city of Germany. It manages the city's U-Bahn underground railway, bus, replacement services and ferry networks, but not the S-Bahn urban rail system; the used abbreviation, BVG, has been retained from the company's original name, Berliner Verkehrs Aktiengesellschaft. Subsequently, the company was renamed Berliner Verkehrs-Betriebe. During the division of Berlin, the BVG was split between BVG and BVB. After reunification, the current formal name was adopted; the Berliner Verkehrs Aktiengesellschaft was formed in 1928, by the merger of the Allgemeine Berliner Omnibus AG, the Gesellschaft für Elektrische Hoch- und Untergrundbahnen and the Berliner Straßenbahn-Betriebs-GmbH. On 1 January 1938, the company was renamed Berliner Verkehrs-Betriebe, but the acronym BVG was retained. From 1 August 1949, the BVG networks in East Berlin were operated separately; the two operators were known as BVG and BVG, but from 1 January 1969 the eastern operator was renamed as the Kombinat Berliner Verkehrsbetriebe or BVB.
After the reunification of Berlin, the two operators were recombined into the Berliner Verkehrsbetriebe on 1 January 1992. Prior to the division of Berlin, tram lines existed throughout the city, but BVG abandoned all the tram lines in its part of the city, replacing them all by buses by 1967; however BVG retained its tram lines, on the reunification of Berlin the BVG inherited a considerable network of routes in the eastern half of Berlin. On 9 January 1984, BVG took over the responsibility for operation of the S-Bahn services in West Berlin; this urban rail network had been operated in both halves of Berlin by the Deutsche Reichsbahn, the state rail operator of East Germany, but had been subject to a boycott in the west after the building of the Berlin Wall. With the reunification of Berlin, responsibility for the S-Bahn reverted to Deutsche Bahn AG, the state rail operator of Germany; the S-Bahn is managed by the S-Bahn Berlin GmbH, a subsidiary company of DBAG. BVG took part in the Berlin M-Bahn project, an urban maglev system, in the period between 1984 and 1992.
The project used a section of the U-Bahn right of way, out of service due to the building of the Berlin Wall, was dropped with the fall of that wall. The BVG launched the MetroNetz on 12 December 2004 which remodeled the tram and bus network to create 24 tram and bus lines covering parts of the city that weren't served by S-Bahn or U-Bahn. BVG operates an urban rapid transit rail system; the U-Bahn now comprises a total length of 147 kilometres. Trains run every two to five minutes during peak hours, every five minutes for the rest of the day and every ten minutes in the evening and on Sunday. U-Bahn service is provided by 1266 carriages, of which 500 are used on the earlier small-profile lines and 766 are used on the large-profile lines; these cars travel 132 million km, carrying 400 million passengers, over the year. BVG operates a tram network comprising 22 tram lines with 377 stops and measuring 293.78 km in length. Of these, nine are designated as part of the MetroNetz, which provide a high frequency service in areas poorly served by the U-Bahn and S-Bahn.
These MetroTram tram lines are recognisable by an M prefix to their route number, are the only tram routes to operate 24 hours a day. Tram service is provided by 391 carriages, of which 154 are modern low floor carriages and 237 are older carriages. All of the remaining network is within the confines of the former East Berlin, as all the routes in the former West Berlin were abandoned during the period of the city's partition. However, there have been some extensions of routes across the former border since reunification, most remarkably to the city’s new main railway station Berlin Hauptbahnhof. BVG operates a network of 149 daytime bus routes serving 2634 stops and a total route length of 1,675 kilometres, together with a night bus network of 63 bus routes serving 1508 stops and a total route length of 795 kilometres. Seventeen of BVG's bus routes are designated as part of the MetroNetz, which provides a high frequency service in areas poorly served by the U-Bahn and S-Bahn. Like the MetroTram tram routes, these MetroBus routes can be recognised by an M prefix to their route number.
A further 13 BVG-operated bus routes are express routes with an X prefix to their route number. BVG bus service is provided by a fleet of 1349 buses, of which no fewer than 407 are double-decker buses. Whilst such buses are common in Ireland and the United Kingdom, their use elsewhere in Europe is uncommon. Route 218 is operated by ex-BVG vintage vehicles now in preservation but used in revenue-earning service; the services depart from Theodor-Heuss Platz every two hours from 11:15 to 19:15 and return from Pfaueninsel from 10:00 to 20:00. Berlin has an extensive network of waterways within its city boundaries, including the Havel and Dahme rivers, many linked lakes and canals; these are crossed by six passenger ferry routes that are operated by the BVG. The BVG is a member of the Verkehrsverbund Berlin-Brandenburg, the transport association run by public transport providers in the German states of Berlin and Brandenburg; this body
Wedding is a locality in the borough of Mitte, Berlin and was a separate borough in the north-western inner city until it was fused with Tiergarten and Mitte in Berlin's 2001 administrative reform. At the same time the eastern half of the former borough of Wedding—on the other side of Reinickendorfer Straße—was separated as the new locality of Gesundbrunnen. In the 12th century, the manor of the nobleman Rudolf de Weddinge was located on the small Panke River in the immediate vicinity of today's Nettelbeckplatz; the farmstead, which burned down more than once, remained abandoned in the forest until the 18th century. In the mid-18th century, while Gesundbrunnen was being built up as a health resort and spa town and prostitution moved into Wedding, transforming it into a pleasure district. In 1864, Ernst Christian Friedrich Schering established the Schering pharmaceutical company on Müllerstraße. A large hospital at the western rim of the locality was built between 1898 and 1906 on the initiative of Rudolf Virchow.
The Rotaprint plant was initiated in Wedding in 1904 and became one of the largest employers locally with about 1,000 staff at its height. The constant migration of country-dwellers into the city at the end of the 19th century converted Wedding into a working-class district; the labourers lived in cramped tenement blocks, many in the Wilhelmine Ring. After World War I, Wedding was known as "Red Wedding" as it was renowned for its militant Communist working class. After World War II, Wedding and Reinickendorf together made up the French sector of Berlin; the buildings on the north side of Wedding's Bernauer Straße and the street, including sidewalks, were in the French sector, while the buildings along the southern side were in Soviet territory. When the Berlin Wall was being built in August 1961, many who lived in these buildings frantically jumped from their windows before the buildings could be evacuated and their windows bricked up. Wedding was the western terminus of one of the first refugee tunnels dug underneath the Berlin wall.
It extended from the basement of an abandoned factory on Schönholzer Straße in the Soviet sector underneath Bernauer Straße to another building in the west. Though marvellously well constructed and kept secret, the tunnel was plagued by water from leaking pipes, had to be shut down after only a few days of operation. A section of the wall has been reconstructed near the spot on Bernauer Straße where the tunnel ended. Two sections of wall run parallel to one another down the street with a "death strip" in the middle. A nearby museum documents the history of the wall. Today, Wedding is one of the poorest areas of Berlin, with a high unemployment rate. 17% of the population live on social welfare. Foreigners make up 30% of the population. Low rental costs accompany the poverty in Wedding. Therefore, like many inexpensive areas in large cities, it is home to a vibrant artists' community. Many galleries have been founded by artists to provide a space for themselves and their peers to showcase their works.
Wedding has so far not experienced the development of the 1990s in Berlin. Unlike many other 19th-century working class districts like Prenzlauer Berg, the original character of Wedding has been preserved; however and more students and artists have moved to Wedding due to lower rental costs and a high level of quality of life. As a result, many new Bohemian cafés, restaurants and clubs, organic food stores and markets have been established, an art-house cinema and an urban gardening project has started and high-brow galleries have discovered that area, it is still said though to be a place to find the Schnauze mit Herz of the Berlin working class. Along with Kreuzberg, Wedding is one of the most ethnically diverse localities of Berlin; the multicultural atmosphere is visible in the bilingual shop signs. In recent years Wedding has seen a significant influx of Africans, many of whom have settled in the Afrikanisches Viertel, or African Quarter. Wedding is home to an East Asian community from China, reflected in many Asian and African stores and restaurants.
As of 2011, the ethnic make-up of Wedding was 52% of German origin, 18% Turks, 6% Sub-Saharan African, 6% Arabs, 6% Polish, 5% former Yugoslavia, 4.5% Asian. Many buildings are relics of European post-war Modernism; the Schillerpark estate in northern Wedding is part of the Modernist Housing Estates World Heritage Site. Beside monolithic housing blocks, several old buildings survived the war and urban renewal and still have coal-fired heating. A green oasis marks the west borders of the "old red" district, with Volkspark Rehberge and the idyllic Plötzensee, a lake in the southwest, it is a popular summer hang-out offering long lawns. A section of the beach is reserved for a German nudist movement. At Scharnweberstraße 158/159 is Germany's last inner-city dune dating back to Ice Age. Kevin-Prince Boateng, footballer for the Ghana national football team and Schalke 04, grew up in the area. Thomas Dörflein, best known for raising Knut the polar bear. Otto and Elise Hampel, a working-class couple who created a simple method of protest while living in Wedding, Berlin during the early years of World War II.
They were caught and executed. Hardy Krüger, actor Erich Mielke, convicted copkiller and longtime head of the East German Secre
U1 (Berlin U-Bahn)
U1 is a line on the Berlin U-Bahn, 8.8 kilometres long and has 13 stations. Its traditional line designation was BII, it runs east-west and its eastern end is south of the route of the historical Schlesischen Bahn at the Warschauer Straße S-Bahn station and runs through Kreuzberg, Wittenbergplatz on to the Kurfürstendamm. The eastern section of the line is the oldest part of the Berlin U-Bahn, although it is above ground; the U1 route was part of BII until 1957, where it was renamed to BIV until 1 March 1966. While the main section between Wittenbergplatz and Schlesisches Tor has been designated as line 1 since 1966, the western end of the line has changed twice, it was renumbered to Line "3" and "U3" in 1993, before being renamed U15 until 2004. The increasing traffic problems in Berlin at the end of the 19th century led to a search for new efficient means of transport. Inspired by Werner von Siemens, numerous suggestions were made for overhead conveyors, such as a suspension railway, as was built in Wuppertal, or a tube railway as was built in London.
Siemens and some prominent Berliners submitted a plan for an elevated railway on the model of New York. These people opposed Siemens' suggestion of building an overhead railway in the major street of Friedrichstrasse, but the city of Berlin opposed underground railways, since it feared damage to one of its new sewers. After many years and negotiations, Siemens proposal for an elevated railway line from Warschauer Brücke via Hallesches Tor to Bülowstraße was approved; this was only possible, because it passed through poor areas. The richer residents of Leipziger Straße pressed the city administration to prevent the line using their street. Siemens & Halske carried out all construction work and owned the line; the first sod was turned on 10 September 1896 in Gitschiner Straße. The construction work had to be carried out because the contract with the city of Berlin, signed with the granting of the concession, specified that the line had to be finished within two years, or a penalty of 50,000 marks would be payable.
The railway engineers developed a design for the supporting columns for the elevated railway, but it was unpopular and the architect Alfred Grenander was asked to submit an artistic solution for this problem. For the next 30 years Grenander was the house architect for the underground railway. After tough negotiations with the city of Charlottenburg it was decided to extend the line to Knie along the Tauentzienstrasse, but instead of being elevated it would be a subsurface railway; the management of the city of Berlin board of works regarded the idea of an underground railway sympathetically. Since the underground caused no apparent damage to the new sewer, an underground branch could be built from a junction at Gleisdreieck to Potsdamer Platz, Berlin’s city centre; the national government granted permission for the planning changes on 1 November 1900. The total length of the elevated and underground railway was now 10.1 kilometres. The largest part of the route 8 kilometres, would be established on viaducts and connect eleven elevated stations.
In addition there would be 2 kilometres of underground line with three underground stations. The planners believed that 8-carriage trains would not be needed and therefore designed it with 80 m-long platforms, sufficient only for 6-carriage trains; the first 6 kilometres of the line was finished in 1901 and on 15 February 1902 the first train ran on the line from Potsdamer Platz to Zoologischer Garten to Stralauer Tor and back to Potsdamer Platz. This allowed many prominent Berliners to participate in the opening trip, including the Prussian minister for public works, Karl von Thielen. On 18 February 1902 the first stage of the Berlin U-Bahn was opened. In March the line was extended to Zoologischer Garten and on 17 August it was extended by 380 m from Stralauer Tor to Warschauer Brücke. There were at that time only two lines: From Warschauer Brücke to Zoologischer Garten via Potsdamer Platz. From Warschauer Brücke directly to Zoologischer Garten. On 14 December the line was extended to Knie; the section between Gleisdreieck and Knie is now part of U2.
In the summer of 1907, the elevated railway company of the new city of Wilmersdorf suggested the building of an underground line to the Wilmersdorf area. It suggested a line to Nürnberger Platz and, if Wilmersdorf would pay to Breitenbachplatz. Since Wilmersdorf municipality had poor transport connections, the Wilmersdorf city fathers were pleased to take up this suggestion; the royal domain of Dahlem, south of Wilmersdorf and was still undeveloped supported a U-bahn connection and wanted it extended from Breitenbachplatz to Thielplatz. However, the future line would run through the city of Charlottenburg, which saw the city of Wilmersdorf as a major competitor for the settlement of wealthy ratepayers. Long negotiations ensued, until in the summer 1910 a solution was found: an additional line would be built under the Kurfürstendamm to Uhlandstraße. Work began on these lines in the same summer; the double-track Wittenbergplatz station, which only had two side platforms, had to be rebuilt. The new station required five platforms with a sixth prepared for an entrance hall.
The cities of Wilmersdorf and Charlottenburg submitted many suggestions for its design. The house architect of the elevated railway company, Alfred Grenander, was appointed to design the station on the recommendation of the royal police chief; the add
The Spree is a river that flows through the Saxony and Berlin states of Germany, in the Ústí nad Labem region of the Czech Republic. 400 kilometres in length, it is a left bank tributary of the River Havel, which itself flows into the Elbe and the North Sea. It is the river; the reach of the river between the Dämeritzsee and Müggelsee to the east of Berlin is known as the Müggelspree. The source of the Spree is a small pond surrounded by a lawn & trees in Neugersdorf, Germany, in the Lusatian Highlands near the Czech border; the Spree flows into the Volksbad, a large outdoor swimming pool at Volksbadstraße 15. Exiting northwest it passes under a railway line at Rumburger Straße & continues towards the Spreequelle in Ebersbach; the Spree runs on the border for a short distance at two points before leaving the hills and passing through the old city of Bautzen/Budyšin, the center of the Sorbs in Upper Lusatia. Just to the north of Bautzen the river flows through the Bautzen Reservoir. Further north the river passes through the city of Spremberg and the Spremberg Reservoir before reaching the city of Cottbus.
To the north of Cottbus the river enters the Spreewald, a large wetlands area in Lower Lusatia. In the Spreewald the river passes through the towns of Lübben and Leibsch. Just below Leibsch, the Dahme Flood Relief Canal diverts water from the Spree to run into the River Dahme at Märkisch Buchholz; the Spree continues north from Leibsch before flowing into the Neuendorfer See at the northern edge of the Spreewald. From the Neundorfer See it flows in an easterly direction to the Schwielochsee, in a northerly and westerly direction to the town of Fürstenwalde. From Fürstenwalde the river continues to flow westwards, through the Dämeritzsee and Müggelsee, to Köpenick in the southeastern part of Berlin, where it is joined by its tributary, the River Dahme; the final reach of the Spree is. It flows through the city centre of Berlin to join the River Havel in Spandau, one of Berlin’s western boroughs, which itself merges with the Elbe to enter the sea in Cuxhaven, after flowing through Hamburg. On its route through Berlin, the river passes Berlin Cathedral, the Reichstag and the Schloss Charlottenburg.
The renowned Museum Island, with its collection of five major museums, is an island in the Spree. The Badeschiff is a floating swimming pool moored in the Spree. Small craft, such as punts, are used in wetlands of the Spreewald. Larger craft can reach as far upstream as Leibsch, although the upper reaches are shallow and are only used by leisure craft; some intermediate reaches are by-passed by canals. For a stretch of about 20 kilometres east of and flowing through Fürstenwalde, the river forms part of the Oder-Spree Canal. On this reach, on the reach west of the confluence with the River Dahme at Köpenick, the river forms part of secondary commercially link between Berlin and the River Oder and hence Poland; the canal diverges from the Spree just east of Fürstenwalde and joins the River Dahme at the Seddinsee. In Berlin, the Spree forms part of a dense network of navigable waterways, many of which are artificial, which provide a wide choice of routes. Several important commercial harbours can be found on this network, tugs and barges move sand, grain and beer.
Tour boats tour its adjoining waterways on a frequent basis. The name of the river Spree was recorded by Thietmar of Merseburg as Sprewa. People living at the Spree river were in old German language called Spreewaner; the river gives its name to several German districts: Spree-Neiße Oder-Spree Many people died in the Spree during the Cold War while trying to cross the Berlin Wall, including children who drowned with rescuers not allowed to enter the river to save them. Berlin Referendum Animation - Short article on the Mediaspree referendum Panorama Spree - Panoramic view of the river in Berlin "Spree". Encyclopædia Britannica. 1911
A third rail is a method of providing electric power to a railway locomotive or train, through a semi-continuous rigid conductor placed alongside or between the rails of a railway track. It is used in a mass transit or rapid transit system, which has alignments in its own corridors or fully segregated from the outside environment. Third rail systems are always supplied from direct current electricity; the third-rail system of electrification is unrelated to the third rail used in dual gauge railways. Third-rail systems are a means of providing electric traction power to trains using an additional rail for the purpose. On most systems, the conductor rail is placed on the sleeper ends outside the running rails, but in some systems a central conductor rail is used; the conductor rail is supported on ceramic insulators or insulated brackets at intervals of around 10 feet. The trains have metal contact blocks called collector shoes which make contact with the conductor rail; the traction current is returned to the generating station through the running rails.
In the US, the conductor rail is made of high conductivity steel or steel bolted to aluminium to increase the conductivity. Elsewhere in the world, extruded aluminum conductors with stainless steel contact surface or cap, is the preferred technology due to its lower electrical resistance, longer life, lighter weight; the running rails are electrically connected using wire bonds or other devices, to minimise resistance in the electric circuit. Contact shoes can be positioned below, above, or beside the third rail, depending on the type of third rail used: these third rails are referred to as bottom-contact, top-contact, or side-contact, respectively; the conductor rails have to be interrupted at level crossings and substation gaps. Tapered rails are provided at the ends of each section, to allow a smooth engagement of the train's contact shoes; the position of contact between the train and the rail varies: some of the earliest systems used top contact, but developments use side or bottom contact, which enabled the conductor rail to be covered, protecting track workers from accidental contact and protecting the conductor rail from frost, ice and leaf-fall.
Because third rail systems present electric shock hazards close to the ground, high voltages are not considered safe. A high current must therefore be used to transfer adequate power, resulting in high resistive losses, requiring closely spaced feed points; the electrified rail threatens electrocution of anyone falling onto the tracks. This can be avoided by using platform screen doors, or the risk can be reduced by placing the conductor rail on the side of the track away from the platform, when allowed by the station layout; the risk can be reduced by having an insulated coverboard to protect the third rail from contact, although many systems do not use one. In some modern systems such as the ground-level power supply, the safety problem is avoided by splitting the power rail into small segments, each of, only powered when covered by a train. There is a risk of pedestrians walking onto the tracks at level crossings. In the US, a 1992 Supreme Court of Illinois decision affirmed a $1.5 million verdict against the Chicago Transit Authority for failing to stop an intoxicated person from walking onto the tracks at a level crossing in an attempt to urinate.
The Paris Metro has graphic warning signs pointing out the danger of electrocution from urinating on third rails, precautions which Chicago did not have. The end ramps of conductor rails present a practical limitation on speed due to the mechanical impact of the shoe, 160 km/h is considered the upper limit of practical third-rail operation; the world speed record for a third rail train is 174 km/h attained on 11 April 1988 by a British Class 442 EMU. In the event of a collision with a foreign object, the beveled end ramps of bottom running systems can facilitate the hazard of having the third rail penetrate the interior of a passenger car; this is believed to have contributed to the death of five passengers in the Valhalla train crash of 2015. Third rail systems using top contact are prone to accumulations of snow, or ice formed from refrozen snow, this can interrupt operations; some systems operate dedicated de-icing trains to deposit an oily fluid or antifreeze on the conductor rail to prevent the frozen build-up.
The third rail can be heated to alleviate the problem of ice. Unlike third rail systems, overhead line equipment can be affected by strong winds or freezing rain bringing the wires down and stopping all trains. Thunderstorms can disable the power with lightning strikes on systems with overhead wires, disabling trains if there is a power surge or a break in the wires; because of the gaps in the conductor rail a train can stop in a position where all of its power pickup shoes are in gaps, so that no traction power is available. The train is said to be "gapped". Another train must be brought up behind the stranded train to push it on to the conductor rail, or a jumper cable may be used to supply enough power to the train to get one of its contact shoes back on the third rail. Avoiding this problem requires a minimum length of trains that can be run on a line. Locomotives have either had the backup of an on-board diesel engine system, or have been connected to shoes on the rolling stock; the first idea for feeding elec
The Berlin U-Bahn is a rapid transit railway in Berlin, the capital city of Germany, a major part of the city's public transport system. Together with the S-Bahn, a network of suburban train lines, a tram network that operates in the eastern parts of the city, it serves as the main means of transport in the capital. Opened in 1902, the U-Bahn serves 173 stations spread across ten lines, with a total track length of 151.7 kilometres, about 80% of, underground. Trains run every two to five minutes during peak hours, every five minutes for the rest of the day and every ten minutes in the evening. Over the course of a year, U-Bahn trains travel 132 million km, carry over 400 million passengers. In 2017, 553.1 million passengers rode the U-Bahn. The entire system is maintained and operated by the Berliner Verkehrsbetriebe known as the BVG. Designed to alleviate traffic flowing into and out of central Berlin, the U-Bahn was expanded until the city was divided into East and West Berlin at the end of World War II.
Although the system remained open to residents of both sides at first, the construction of the Berlin Wall and the subsequent restrictions imposed by the Government of East Germany limited travel across the border. The East Berlin U-Bahn lines from West Berlin were severed, except for two West Berlin lines that ran through East Berlin; these were allowed to pass through East Berlin without stopping at any of the stations, which were closed. Friedrichstraße was the exception because it was used as a transfer point between U6 and the West Berlin S-Bahn system, a border crossing into East Berlin; the system was reopened following the fall of the Berlin Wall, German reunification. The Berlin U-Bahn is the most extensive underground network in Germany. In 2006, travel on the U-Bahn was equivalent to 122.2 million km of car journeys. The Berlin U-Bahn was built in three major phases: Up to 1913: the construction of the Kleinprofil network in Berlin, Schöneberg, Wilmersdorf. At the end of the 19th century, city planners in Berlin were looking for solutions to the increasing traffic problems facing the city.
As potential solutions and inventor Ernst Werner von Siemens suggested the construction of elevated railways, while AEG proposed an underground system. Berlin city administrators feared that an underground would damage the sewers, favouring an elevated railway following the path of the former city walls. Years of negotiations followed until, on 10 September 1896, work began on a elevated railway to run between Stralauer Tor and Zoologischer Garten, with a short spur to Potsdamer Platz. Known as the "Stammstrecke", the route was inaugurated on 15 February 1902, was popular. Before the year ended, the railway had been extended: by 17 August, east to Warschauer Brücke. In a bid to secure its own improvement, Schöneberg wanted a connection to Berlin; the elevated railway company did not believe such a line would be profitable, so the city built the first locally financed underground in Germany. It was opened on 1 December 1910. Just a few months earlier, work began on a fourth line to link Wilmersdorf in the south-west to the growing Berlin U-Bahn.
The early network ran east to west, connecting the richer areas in and around Berlin, as these routes had been deemed the most profitable. In order to open up the network to more of the workers of Berlin, the city wanted north-south lines to be established. In 1920, the surrounding areas were annexed to form Groß-Berlin, removing the need for many negotiations, giving the city much greater bargaining power over the private Hochbahngesellschaft; the city mandated that new lines would use wider carriages—running on the same, standard-gauge track—to provide greater passenger capacity. Construction of the Nord-Süd-Bahn connecting Wedding in the north to Tempelhof and Neukölln in the south had started in December 1912, but halted for the First World War. Work resumed in 1919, although the money shortage caused by hyperinflation slowed progress considerably. On 30 January 1923, the first section opened between Hallesches Tor and Stettiner Bahnhof, with a continuation to Seestraße following two months later.
Underfunded, the new line had to use trains from the old Kleinprofil network. The line branched at Belle-Alliance-Straße, now. In 1912, plans were approved for AEG to build its own north-south underground line, named the GN-Bahn after its termini and Neukölln, via Alexanderplatz. Financial difficulties stopped the construction in 1919; the first section opened on 17 July 1927 between Boddinstraße and Schönleinstraße, with the intermediate Hermannplatz becoming the first