German border at Marienborn (E)/Helmstedt (W), also called Checkpoint Alpha. A third route to Southwestern Germany consisted of today's A 9 and A 4 with border crossing at Wartha (E)/Herleshausen (W). A fourth (via today's A 9) to Southern Germany had border crossings originally at Mount Juchhöh (E)/Töpen (W) and later at Hirschberg upon Saale (E)/ Rudolphstein (a part of today's Berg in Upper Franconia) (W). The latter three routes used autobahns built during the Nazi era. They left West Berlin at Checkpoint Dreilinden, also called Checkpoint Bravo (W)/Potsdam-Drewitz (E). Transit routes to Poland were via today's A 11 to Nadrensee-Pomellen (East Germany, GDR)/Kołbaskowo (Kolbitzow) (PL), eastwards via today's A 12 to Frankfurt upon Oder (GDR)/Słubice (PL), or southeastwards via today's A 13 and A 15 to Forst in Lusatia/Baršć (GDR)/Zasieki (Berge) (PL). Additional routes led to Denmark and Sweden by ferry between Warnemünde (GDR) and Gedser (DK) and by ferry between Sassnitz (GDR) and Rønne (DK) or Trelleborg (S). Routes to Czechoslovakia were via Schmilka (GDR)/Hřensko (Herrnskretschen) (ČSSR) and via Fürstenau (a part of today's Geising) (GDR)/Cínovec (Cinvald/Böhmisch Zinnwald) (ČSSR). The transit routes were also used for East German domestic traffic. This meant that transit passengers could potentially meet with East Germans and East Berliners at restaurants at motorway rest stops. Since such meetings were deemed illegal by the East German government, border guards would calculate the travel duration from the time of entry and exit of the transit route. Excessive time spent for transit travel could arouse their suspicion and prompt questioning or additional checking by the border guards. Western coaches could stop only at dedicated service areas since the East German government was concerned that East Germans might potentially use coaches to escape into the West. On 1 September 1951 East Germany, because of a shortage in foreign currencies, started to levy road tolls on cars using the transit routes. At first, the toll amounted to 10 Ostmark per passenger car and 10 to 50 for trucks, depending on size. Ostmarks had to be exchanged into Deutsche Mark at a rate of 1:1. On 30 March 1955, East Germany raised the toll for passenger cars to 30 Deutsche Marks, but after West German protests, in June of the same year, it changed it back to the previous rate. Following a new agreement between East and West Germany, starting from 1 January 1980 the Federal Government in Bonn