At the end of the war in May 1945, NSB took control over the construction. They shifted focus towards bringing the existing line up to standards. The Dunderland Line was bought by the state and taken over by NSB on 1 July 1947. Class 87 diesel multiple units were introduced between Elsfjord and Mosjøen, later extended to Majavatn, until 1951. An express train started running directly from Trondheim in 1949 and the next year a night train service was introduced. Sleeping cars to Mo i Rana were introduced in 1956, and to Mosjøen in 1970.