closed down both Berlin Anhalter Bahnhof and Berlin Nordbahnhof, on 18 May 1952. On 28 August 1951, the Reichsbahn opened a new connection – from Spandau via Berlin Jungfernheide station – for the S-Bahn lines connecting East German suburbs to the west of West Berlin (namely Falkensee, Staaken) with East Berlin, thus circumventing the centre of West Berlin. In June 1953, the Reichsbahn further cut off West Berlin from its East German suburbs by the introduction of additional express S-Bahn trains (). These routes originated from several East German suburbs bordering West Berlin (such as Falkensee, Potsdam, Oranienburg, Staaken, and Velten), crossing West Berlin non-stop until reaching its destinations in East Berlin. However, the regular S-Bahn connections with West Berlin's East German suburbs, stopping at every Western station, continued. From 17 June to 9 July 1953, East Germany blocked off all traffic between East and West due to the Uprising of 1953 in East Germany. From 4 October 1953, all S-Bahn trains crossing the border between East Germany and Berlin had to pass a border checkpoint in East Germany. Travellers from East Germany were checked before entering any part of Berlin, to identify individuals intending to escape into West Berlin or smuggling rationed or rare goods into West Berlin. S-Bahn trains were checked at Hoppegarten, Mahlow, and Zepernick in East Germany bordering East Berlin and in Hohen Neuendorf, Potsdam-Griebnitzsee, and Staaken-Albrechtshof in East Germany bordering West Berlin. On 4 June 1954, the Bahnhof Hennigsdorf Süd station located next to West Berlin was opened solely for border controls, also to monitor West Berliners entering or leaving East Berlin, which they could still do freely, while they were not allowed to cross into East Germany proper without a special permit. 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,