8 February 2009. Transport and transit travel West Berliners could travel to West Germany and all Western and non-aligned states at all times, except during the Berlin Blockade by the Soviet Union (24 June 1948 to 12 May 1949) when there were restrictions on passenger flight capacity imposed by the airlift. Travelling to and from West Berlin by road or train always required passing through East German border checks, since West Berlin was an enclave surrounded by East Germany and East Berlin. On 2 October 1967, six years after the Wall was constructed, tram tracks in West Berlin were removed because the authorities wanted to promote car usage, meaning that the tram system remaining today runs almost entirely within the former East Berlin. Road traffic There were no dedicated walled-off road corridors between West Germany and West Berlin under West German jurisdiction, and travellers needed to pass through East Germany. A valid passport was required for citizens of West Germany and other western nationals to be produced at East German border checks. West Berliners could get admission only through their identity cards (see above). For travel from West Berlin to Denmark, Sweden and West Germany via dedicated East German transit routes (), East German border guards issued a transit visa for a fee of 5 Western Deutsche Mark. For journeys between West Berlin and Poland or Czechoslovakia through East Germany, each traveller was also required to present a valid visa for the destination country. The transit routes for road travel connecting West Berlin to other destinations usually consisted of autobahns and other highways, marked by Transit signs. Transit travellers () were prohibited to leave the transit routes, and occasional traffic checkpoints would check for violators. There were four transit routes between West Berlin and West Germany: One between West Berlin's Heerstraße with the East German checkpoint in Dallgow until 1951, then replaced by Staaken for destinations in Northern Germany (originally via highway F 5) at the Eastern checkpoint in Horst (a part of today's Nostorf) and the Western Lauenburg upon Elbe. These were replaced on 20 November 1982 by a new autobahn crossing at Zarrentin (E)/Gudow (W). On 1 January 1988, the new Stolpe checkpoint opened on this route to West Berlin. This is part of today's Hohen Neuendorf (E)/Berlin-Heiligensee (W). A second transit route led to Northwestern and Western Germany – following today's A 2 – crossing the inner