On the 13 August 1961, it was the biggest turning point in the operation and network for the S-Bahn. As relations between East and West began to sour with the coming of the Cold War, it 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. From 1958 onward, some S-Bahn trains ran non-stop through the western sectors from stations in East Berlin to stations on outlying sections in East Germany so as to avoid the need for such controls. East German government employees were then forbidden to use the S-Bahn since it travelled through West Berlin. The S-Bahn has also been operated in two separate subnets of the Deutsche Reichsbahn. In East Berlin, the S-Bahn retained a transport share of approximately 35 percent, the mode of transport with the highest passenger share. In the 1970s and 1980s the route network continued to grow. In particular, the new housing estates were connected to the grid in the northeast of the city (Marzahn and Hohenschönhausen). The construction of the Berlin Wall led to West Berlin calling for the unions and politicians to boycott the S-Bahn. Subsequently, passenger numbers fell. However, the Berlin S-Bahn strike brought the S-Bahn to the attention of the public, and aroused the desire for West Berlin to manage its section of the S-Bahn itself. In 1983 negotiations of representatives of the Senate, the SNB and the Deutsche Reichsbahn took place. In December 1983, these were concluded with Allied consent to the agreement between the Deutsche Reichsbahn and the Berlin Senate for the transfer of operating rights of the S-Bahn in the area of West Berlin. The BVG received the oldest carriages from the DR; but the BVG was eager to quickly get to modern standards for a subway. Therefore, soon new S-Bahn trains were purchased on their behalf, which are still in use on the Berlin S-Bahn network as the 480 series. Even before the Wall fell, there were efforts to substantial re-commissioning of the S-Bahn network in West Berlin. After the Berlin Wall came down in November 1989, the first broken links were re-established, with Friedrichstraße on 1 July 1990, as the first. The BVG and DR jointly marketed the services soon after the reunification. Administratively, the divided S-Bahn networks remained separate in this time of momentous changes, encompassing German reunification and reunification of Berlin into a single city, although the dividing line was no longer the former Berlin Wall.