in 1963, the lübeck–puttgarden and rødby havn–copenhagen lines were completed as part of the vogelfluglinie (literally: "bird flight line") to copenhagen. this increased the range of long distance trains between lübeck and hamburg. in addition to the trains to copenhagen there were interzone trains (trains between east and west germany) to rostock. express trains, the "merkur" trans europ express and "trans-europ-express-marchandises" freight trains were hauled to puttgarden by the class db-221 diesel locomotives.