The distinction is most easily made when there are two systems such as New York's subway and the LIRR and Metro-North, Paris ' RER and Métro, London's Overground and the tube lines of the Underground, Barcelona's Metro and Rodalies, S-Bahn and U-Bahn systems in Berlin, Frankfurt, Munich or Vienna, the JR lines and the Metro in Tokyo.

Nearly all larger metropolitan areas are served by S-Bahn, U-Bahn, Strassenbahn and / or bus networks

Relatively few cities have a full-fledged underground U-Bahn system, and S-Bahn ( suburban commuter railway ) systems are far more common.

In some cities the distinction between U-Bahn and S-Bahn systems is blurred, for instance some S-Bahn systems run underground, have frequencies similar to U-Bahn, and form part of the same integrated transport network.

New U-Bahn and S-Bahn lines were planned to run directly beneath almost the whole length of the axis, and the city's entire underground network reoriented to gravitate towards this new hub ( at least one tunnel section, around 220 metres in length, was actually constructed and still exists today, buried some 20 metres beneath the Tiergarten, despite having never seen a train ).

Below ground, the U-Bahn section through Potsdamer Platz had closed entirely ; although the S-Bahn line itself remained open, it suffered from a quirk of geography in that it briefly passed through East German territory en route from one part of West Berlin to another.

After major refurbishment, the S-Bahn line and station reopened on 1 March 1992, followed by the U-Bahn on 13 November 1993.

* The London Underground ( which is treated as heavy rail, unlike German U-Bahn ) has many parts that function like an S-Bahn, the Metropolitan and District lines, with their full-sized trains and their long length are especially S-Bahn like.

The central square in Mitte is Alexanderplatz with the prominent Fernsehturm ( TV tower ), Germany's highest building, and the large railway station with connections to many subway ( U-Bahn ), tramway ( Straßenbahn ), city trains ( S-Bahn ) and buses.

Unlike the U-Bahn, the S-Bahn crosses the Berlin city and state border into the surrounding state of Brandenburg, e. g. to Potsdam.

The S-Bahn is operated by S-Bahn Berlin GmbH, a subsidiary of the Deutsche Bahn, whilst the U-Bahn is run by BVG, the main public transit company for the city of Berlin.

Close to the U-Bahn station Rathaus Spandau is the Berlin-Spandau railway station of the Berlin S-Bahn line S75 and the Deutsche Bahn for regional and intercity transport.

Berlin Jungfernheide is a railway station located at Charlottenburg-Nord, in the Charlottenburg-Wilmersdorf district of Berlin, served by the S-Bahn lines and, the U-Bahn line and Regional-Express trains of the Deutsche Bahn.

This situation was intensified by the building of the U-Bahn line, which was essentially a parallel service to the S-Bahn to Spandau.

It was not until 2002 that the Ringbahn was operated again in its entirety and Jungfernheide enjoyed a status as an important interchange between S-Bahn and U-Bahn, owing to its being served by direct trains from the majority of Berlin's central districts.

A special case involved the Friedrichstraße train station in East Berlin, which one could reach from West Berlin by U-Bahn, S-Bahn or long-distance train.

S-Bahn, U-Bahn and tram lines ( schematic map )

S-Bahn, U-Bahn and tram lines ( topographical map )

The O-Bahn – from the Latin omnibus (" for all people ") and the German bahn ( railway, as in S-Bahn and U-Bahn ) – was conceived by Daimler-Benz to enable buses to avoid traffic congestion by sharing tram tunnels in the German city of Essen.

A successful Maiolica tile factory was established there in 1905, and many of those tiles were used to decorate the Old Elbe Tunnel in Hamburg and several Berlin U-Bahn stations.

Improvements to the infrastructure were needed ; in 1896 the construction of the subway ( U-Bahn ) began and was completed in 1902.

Originally designed for and used by the Frankfurt U-Bahn ( subway / metro system ), the model of car was adopted for light-rail use by transit systems in Edmonton, Calgary, and San Diego, during a period in which few purpose-built trams were being manufactured.

Introduced in 1977, they entered service in 1980 and were never exported outside of Germany's Frankfurt U-Bahn.

During the time of the Berlin Wall, a number of Berlin U-Bahn stations on West Berlin lines became " ghost stations " ( Geisterbahnhöfe ) because they were on lines which passed through East Berlin territory.

Plans for a U-Bahn dating to 1912 – 14 were revived and discussions took place in 1929, but the Great Depression again necessitated abandoning planning.

Both in 1937 and after the Anschluß, when Vienna became the largest city by surface area in the Third Reich, ambitious plans for a U-Bahn, as well as a new central railway station, were discussed.

Two proposals for U-Bahn systems were nonetheless presented, in 1953 and 1954.

Construction began on 3 November 1969 on and under Karlsplatz, where three lines of the basic network were to meet, and where central control of the U-Bahn was initially located.

Parts of the building's marble walls were said to be used to build the Soviet war memorial in Treptower Park or to renovate the nearby war-damaged Mohrenstraße U-Bahn station which is an early version of an urban legend.

This term was used to describe certain stations on Berlin's U-Bahn and S-Bahn metro networks that were closed during the period of Berlin's division during the Cold War.

However, there were three lines — the U-Bahn lines now designated U6 and U8, and the Nord-Süd Tunnel on the S-Bahn — that ran for the most part through West Berlin but passed through a relatively short stretch of East Berlin territory in the city centre.

The U-Bahn stop at Studentenstadt was opened on October 19, 1971, just as 8 of the 14 houses were completed.

Both buildings were disassembled, renovated, and then reassembled two metres higher than their original location after completion of U-Bahn construction.

Until construction of the U-Bahn, the trams were the primary mode of public transport in Vienna.

Beginning in 1978, in the course of construction of the U-Bahn, tram routes parallelling U-Bahn routes were introduced.

It was the final stop in West Berlin ; the next station, Berlin Friedrichstraße, was in the Soviet zone, although it served as a stop on both the West Berlin S-and U-Bahn systems ; these parts of the station were sealed off and inaccessible to East Berliners.

Platforms for the planned extension to U-Bahn line 5 were also included, as were platforms for the cancelled Transrapid maglev train.

* 5 U-Bahn lines with gross length ( operational length, built length, of rail ) and 476. 7 million passengers ( approximately 50 million more than in 2004 )

In Taut's case, the housing he built in south-west Berlin during the 1920s, is still occupied, and can be reached by going easily from the U-Bahn stop Onkel Toms Hütte.

The U-Bahn arrived first, from the south ; begun on 10 September 1896, it opened on 18 February 1902, with a new and better sited station being provided on 29 September 1907, and the line itself being extended north and east on 1 October 1908.

Founded by German merchant Georg Wertheim ( 1857 – 1939 ), designed by architect Alfred Messel ( 1853 – 1909 ), opened in 1897 and extended several times over the following 40 years, it ultimately possessed a floor area double that of the Reichstag, a 330-metre-long granite and plate glass facade along Leipziger Straße, 83 elevators, three escalators, 1, 000 telephones, 10, 000 lamps, five kilometres of pneumatic tubing for moving items from the various departments to the packing area, and a separate entrance directly from the nearby U-Bahn station.

The new U-Bahn station was being built at the same time as the hotel and actually ran through the hotel's basement, cutting it in half, thus making the construction of both into something of a technical challenge, but unlike the Wertheim department store ( and contrary to several sources ), the hotel did not enjoy a separate entrance directly from the station.

The closest underground stop is " Simmering " ( Vienna U-Bahn, line U3 ), about 2 km away from the cemetery.

As an example of the GDR regime's desire for hard currency, in the 1980s, in the Berlin Friedrichstraße subway ( U-Bahn ) station, there was an Intershop kiosk on the platform of the U6 line created specifically for travellers from West Berlin who may not have wanted to pass through the GDR border controls.

The U-Bahn station was opened on 1 October 1980 ( designed by R. G. Rümmler ) the extension of the from Richard-Wagner-Platz to Rohrdamm.

The bodies of the Siemens Modular Metro trains evolved from the 1993 DT2 Series used in the Nuremberg U-Bahn whose design in turn came from production of the A Series built for the nearby Munich U-Bahn, but now also used in Nuremberg.

The Fröttmaning subway station was expanded from two to four tracks, while the Marienplatz U-Bahn station was outfitted with additional pedestrian connector tunnels running parallel to the subway tracks, which lead towards the S-Bahn portion of the station, lessening congestion among passengers making connections to the Munich S-Bahn.

The station on the first Berlin U-Bahn line from Potsdamer Platz to Stralauer Tor was opened on February 18, 1902 on a viaduct above Skalitzer Straße.

The station on the first Berlin U-Bahn line from Potsdamer Platz to Stralauer Tor was opened on February 18, 1902.

The U1 platform on a viaduct at the banks of the Landwehrkanal opened on 18 February 1902 with Berlin's first U-Bahn line ( Stammstrecke ) from Stralauer Tor to Potsdamer Platz.

The station's name literally means " railway triangle " or wye in English and marks the spot of an earlier major train hub opened in 1902, where the three branches of the first Stammstrecke U-Bahn line from Zoologischer Garten, Potsdamer Platz and Warschauer Brücke met.

It became desirable to re-establish the U-Bahn line that had previously been severed, requiring the removal of the M-Bahn from its right of way.