In 1951, the Reichsbahn began construction work on the Berlin outer-circle railway line. This circular line connected all train routes heading for West Berlin and accommodated all domestic GDR traffic, thus directing railway traffic into East Berlin while by-passing West Berlin. Commuters in the East German suburbs around West Berlin now boarded Sputnik express trains, which took them into East Berlin without crossing any western sectors. With the completion of the outer-circle railway, there was no further need for express S-Bahn trains crossing the West Berlin border and thus their service ended on 4 May 1958, while stopping S-Bahn trains continued service. However, while East Germans could get off in West Berlin, West Berliners needed the hard-to get permits to enter East Germany by S-Bahn. With the construction of the Berlin Wall on 13 August 1961, all remaining railway traffic between West Berlin and its East German suburbs ended. Rail traffic between East and West Berlin was sharply reduced and restricted to a small number of checkpoints under GDR control. East Berliners and East Germans were then unable to freely enter and leave West Berlin. However, international visitors could obtain visas for East Berlin upon crossing one of the checkpoints at the Wall.
In 1951, the Reichsbahn began construction work on the Berlin outer-circle railway line. This circular line connected all train routes heading for West Berlin and accommodated all domestic GDR traffic, t.hus directing railway traffic into East Berlin while by-passing West Berlin. Commuters in the East German suburbs around West Berlin now boarded Sputnik express trains, which took them into East Berlin without crossing any western sectors. With the completion of the outer-circle railway, there was no further need for express S-Bahn trains crossing the West Berlin border and thus their service ended on 4 .May 1958, while stopping S-Bahn trains continued service However, while East Germans could get off in West Berlin, West Berliners needed the hard-to get permits to enter East Germany by S-Bahn. With the construction of the Berlin Wall on 13 August 1961, all remaining railway traffic between West Berlin and its East German suburbs ended Rail traffic between East and West Berlin was sharply reduced and restricted to a small number of checkpoints under GDR control. East Berliners and East Germans were then unable to freely enter and leave West Berlin. However, international visitors could obtain visas for East Berlin upon crossing one of the checkpoints at the Wall.