U55 (Berlin U-Bahn)

U55 is a Berlin U-Bahn line that is currently under construction. When completed, it will be very short (only three stations) and will not connect to any other U-Bahn line. It was constructed as part of an extension of the U5 that was postponed due to financial difficulties. As much of the work on this section of the extension had been completed, it was decided to complete it and open the section as a short shuttle line using a single train, to be joined to the U5 at a later date.

The unusual nature of U55 is a result of Berlin's troubled finances. When the German government decided to move from Bonn to Berlin after German reunification, it was decided to refurbish the area around the Reichstag into a modern government complex. As part of this effort, there were plans to extend line U5 from its current western terminus at Alexanderplatz through the city centre, past the Brandenburg Gate and the Reichstag, to the new central train station, Berlin Hauptbahnhof. This "Kanzlerlinie" (Chancellor Line), so nicknamed because it passed through the government quarter, was originally planned as a diagonal line through central Berlin, continuing to Turmstraße in Moabit, where it would link with the U9, and on to Jungfernheide, where it would connect with the S-Bahn ring and U7, and possibly continue to Berlin-Tegel airport, or if this is closed as planned, to the new neighbourhoods to be built in its place. As this was a long-planned route, short tunnels exist at both Jungfernheide and Turmstraße to accommodate the new line. However, these plans were cut back for financial reasons before construction began, and the line was planned instead to terminate at the Hauptbahnhof, with the route to Jungfernheide to be built at an unspecified later date.

In the late 1990s, construction began on the western end of this extension. However, around that time the city council suffered a major financial crisis, and in 1999 completion of the partially built extension was postponed indefinitely.

However, the city had accepted money from the German federal government for the construction work already finished, and by the terms of the agreement, the city would have had to return the money if there were no operating trains on the line. In 2004, the city and federal governments reached a compromise: the city would complete the short section of line that was largely complete between Berlin Hauptbahnhof and Unter den Linden S-Bahn stations and run it as a single-track shuttle with a single train, without any signaling. Although transit planners do not project that such a shuttle will attract a significant ridership, the city determined that the cost of building and operating the line would be less than the cost of returning the money to the federal government.

Service between Berlin Hauptbahnhof and Brandenburger Tor has been delayed until late 2008 owing to extreme groundwater problems at the site of the latter new station. The designation of the line as U55 indicates that it is ultimately intended to connect this extension to U5. Work linking the two must begin by 2010 or subsidy from the federal government will be withdrawn; at the moment, 2009 is the target for the beginning of construction of this section.

Because the U55 is not physically connected to the rest of the U-Bahn system, any trains being delivered to the new line will need to be towed along mainline or S-Bahn tracks to reach a connecting tunnel near Hauptbahnhof.

tations

* Berlin Hauptbahnhof; interchange to the Stadtbahn S-Bahn lines and mainline trains
* Bundestag
* Unter den Linden; interchange to the Nord-Süd Bahn S-Bahn lines

It is likely that the new U- and S-Bahn interchange station at the junction of Wilhelmstraße and Unter den Linden, the site of the current Unter den Linden S-Bahn station, will be renamed Brandenburger Tor. The title "Unter den Linden" will ultimately be given to a station (not yet built) further east at the junction with Friedrichstraße, where the proposed U5 will intersect the U6. This new interchange station will replace the current U6 station at Französische Straße, located a little further to the south on Friedrichstraße, which will then be closed.