In 1949 there were twenty-one various versions of Class XXIII and two Class XXVI locomotives used on the Vestfold Line. New 25 kilograms per meter track were installed. However, the foundation was not resized to suit standard gauge. Between 170 and 240 men were employed and the works cost NOK 41 million. The gauge-converted railway, including the Horten Line, was taken into use on 3 October 1949. The Vestfold Line was the last railway in Norway to receive gauge conversion. Most of the remaining narrow gauge rolling stock was therefore sold to Sweden.