Furthermore, the highly populated boroughs of Steglitz, Wedding and Reinickendorf were in need of rapid transit access to the new center of West Berlin south of the Zoo.

The Wall disrupted transportation between East and West Berlin, making it essential to enhance the internal U-Bahn network.

To improve connectivity and reduce reliance on buses, which were slower and less efficient, West Berlin planned an extensive U-Bahn expansion.

This phase aimed to increase the network's capacity, alleviate congestion of both passengers and trains on existing lines, and provide faster connections to previously underserved areas.

This extension enhanced access to Berlin's western center and addressed areas that lacked efficient public transit.

Completed on 29 January 1971, the new expansion provided Steglitz and Neukölln with rapid connections to the western center, replacing slower buses that were hindered by traffic congestion.

The Berlin Wall's continued presence made internal connectivity crucial, promoting economic growth and improving the quality of life for residents.

Here, U9 trains approach from the left, mimicking side platforms with a single passageway at the north end connecting both sections.

Both road tunnels and associated U-Bahn stations were constructed by West Berlin authorities as part of urban development projects.

In Schloßstraße station itself, the tracks are heading north on the top, in the direction of Rathaus Steglitz on the lower level, however, the offices on the eastern edge of the platform on which was supposed to take the U10.

By these enormous constructed provisions, the cost of one meter underground route exorbitantly to 78,000 Mark (adjusted for purchasing power in today's money).

The intended actually for the U9 station Part (Rzo) is equipped with side platforms, located in the minus-1 level until now has been completed only in the shell and is cut off as a storeroom for the civil protection used.