It has been in operation under this name since December 1930, having been previously called the special tariff area Berliner Stadt-, Ring- und Vorortbahnen ('Berlin city, orbital, and suburban railways').
As such, the Berlin S-Bahn blends elements of a commuter rail service and a rapid transit system.
In its first decades of operation, the trains were steam-drawn; even after the electrification of large parts of the network, some lines remained under steam.
Today, the Berlin S-Bahn is no longer defined as this special tariff area of the national railway company, but is instead just one specific means of transportation, defined by its special technical characteristics, in an area-wide tariff administered by a public transport authority.
The brand name S-Bahn chosen in 1930 mirrored U-Bahn, which had become the official brand name for the Berlin city-owned rapid transit lines begun under the name of Berliner Hoch- und Untergrundbahnen ('Berlin elevated and underground lines'), where the word of mouth had abbreviated Untergrundbahn to U-Bahn, in parallel to U-Boot formed from Unterseeboot ('undersea boat' – submarine).
The Berlin S-Bahn consists today of 16 lines serving 166 stations, and runs over a total route length of 332 kilometres (206 mi).
Unlike the U-Bahn, the S-Bahn crosses Berlin city limits into the surrounding state of Brandenburg, e.g. to Potsdam.
Another curve, the Nordkurve to the north-eastern Ringbahn, was originally served by the S86 line, but it was demolished in preparation of the rebuilding of Ostkreuz station and was not rebuilt afterwards.
Westbound lines S46, S47, S75, and northbound S9 terminate at stations Südkreuz, Schöneweide, Lichtenberg, and Treptower Park, respectively.
[3] The core of this network, that is the cross-city (Stadtbahn) east–west line and the circular Ringbahn, and several suburban branches were converted from steam operation to a third-rail electric railway in the latter half of the 1920s.
The first ideas for this project emerged only 10 years after the completion of the east–west cross-city line, with several concrete proposals resulting from a 1909 competition held by the Berlin city administration.
Another concrete proposal, already very close to the final realisation, was put forward in 1926 by Professor Jenicke of Breslau university.
Many sections of the S-Bahn were closed during the war, both through enemy action and flooding of the Nord–Süd-Bahn tunnel on 2 May 1945 during the final Battle of Berlin.
The exact number of casualties is not known, but up to 200 people are presumed to have perished, since the tunnel was used as a public shelter and also served to house military wounded in trains on underground sidings.
After hostilities ceased in 1945, Berlin was given special status as a "Four-Sector City", surrounded by the Soviet Occupation Zone, which later became the German Democratic Republic (GDR).
As relations between East and West began to sour with the coming of the Cold War, the S-Bahn had become the victim of the hostilities.
Although services continued operating through all occupation sectors, checkpoints were constructed on the borders with East Berlin and on-board "customs checks" were carried out on trains.
Even before the Wall fell, there were efforts to substantial re-commissioning of the S-Bahn network in West Berlin.
Technically, a number of projects followed in the steps of re-establishing broken links in order to restore the former S-Bahn network to its 1961 status after 1990, especially the Ringbahn.
In December 1997 the connection between Neukölln and Treptower Park via Sonnenallee was reopened, enabling S4 trains to run 75% of the whole ring between Schönhauser Allee and Jungfernheide.
MTR Corporation, National Express, Berlin S-Bahn GmbH and RATP Development tendered for their procurement process, and were soon followed by train manufacturer Stadler Rail for their operations from 2018 to 2033.
They serviced the following routes: The connection to Spandau West became in the following years the traditional train course, which was maintained after 1945 until the building of the wall.
[10] The new line includes the stations of Waßmannsdorf and Berlin Brandenburg Airport and has a length of approximately 7.8 kilometres.
With the opening of the airport, the S-Bahn service also began operation, which meant that the lines S45 and S9 were extended as was planned more than 10 years ago.
For the underground excavation in Invalidenstrasse, diaphragm walls were built into the ground and the trench in between was covered with a reinforced concrete lid.
[17][18][19] This stage involves the construction of a curve to the Westhafen and an eastern connection to Wedding inside the northern Ringbahn.
From there, the existing line will run in a southerly direction (in the tunnel layer) to the Berlin Hauptbahnhof east of the North–South mainline.
[20] After construction delays caused by the inflow of groundwater, the COVID-19 pandemic, and the global supply chain crisis, the opening is planned for 2024 at the earliest.
The first north–south S-Bahn tunnel was designed in 1939 with room for an additional two tracks at Potsdamer Platz and to its south for the new line.
Following a decision of the Berlin House of Representatives, the goal is essentially to restore the S-Bahn network to its extent in 1961.