ir ts ) ▁were ▁only ▁connected ▁to ▁East ▁Berlin ▁by ▁a ▁long ▁det our ▁of ▁West ▁Berlin ▁around ▁the ▁Berlin ▁outer ▁ring , ▁the ▁so - called ▁S put nik ▁trains . ▁ ▁Today ▁( 2 0 1 4 ), ▁there ▁are ▁two ▁local ▁trains ▁from ▁Nau en ▁via ▁Sp and au ▁to ▁Berlin , ▁the ▁R B ▁ 1 0 ▁on ▁the ▁original ▁course ▁of ▁the ▁Nau en ▁sub urban ▁trains , ▁i . e . ▁via ▁Berlin ▁Jung fern he ide ▁station ▁to ▁the ▁current ▁Berlin ▁Haupt bahn hof , ▁and ▁the ▁R B ▁ 1 4 ▁crossing ▁Berlin ▁West ▁to ▁East ▁via ▁the ▁Berlin ▁Stadt bahn ▁cross - city ▁railway , ▁and ▁termin ating ▁at ▁the ▁Berlin ▁Sch ö ne feld ▁Airport . ▁ ▁Hamburg ▁On ▁the ▁Hamburg ▁end , ▁an ▁S - B ahn ▁service ▁was ▁established ▁alongside ▁the ▁Berlin – H amb urg ▁line , ▁since ▁long ▁distance ▁traffic ▁was ▁now ▁ins ign ific ant . ▁The ▁third ▁rail ▁supp lying ▁DC ▁power ▁was ▁extended ▁first ▁to ▁Ber ged orf ▁in ▁ 1 9 5 9 ▁and ▁then ▁to ▁A um ühle ▁in ▁ 1 9 6 9 . ▁With ▁the ▁establishment ▁of ▁Hamb urger ▁Verkehr s ver bund ▁in ▁ 1 9 6 7 ▁this ▁route ▁was ▁brand ed ▁as ▁line ▁S 2 ▁( now ▁S 2 1 ; ▁S 2 ▁runs ▁between ▁Al ton a ▁and ▁Ber ged orf ). ▁ ▁After ▁the ▁fall ▁of ▁the ▁Wall ▁ ▁After ▁the ▁fall ▁of ▁the ▁Wall ▁on ▁