The Bratsberg and Brevik Line were electrified before the Vestfold Line, between 1936 and 1949. Electrification of the Vestfold Line took place in three segments. First the segment from Eidanger to Larvik was taken into use on 15 October 1956, then the segment from Larvik to Tønsberg on 20 May 1957 and finally the segment from Tønsberg to Drammen on 1 December 1957. Vy reallocated most and later all of their El 8 locomotives to Drammen District, resulting in them being frequently used on the Vestfold Line. Class 66 multiple units were introduced on the Vestfold Line on 28 May 1967. They ran on trains to Skien until 3 June 1973, after which it only served to Larvik. They were retired on 21 May 1977. El 11 locomotives were used on the Vestfold Line from the 1970s. From the late 1970s and early 1980s, these were replaced with El 13.