 The opening of in 1935 caused a major rework of the tram and bus lines when passage through no longer was mandatory when travelling from to .The first underground parts of the Stockholm Metro opened in 1933 on the stretch from to , although it would be trafficked by suburban trams gaining electricity from overhead wires until special metro vehicles was introduced in 1950 which collected its power from a third rail.In addition to trams, motorbuses and the metro, SS once operated a large trolleybus system from 1941 until 1964.