The preliminary earthworking on route up to Lønsdal was finished by the end of the war, and this segment of the line could open on 8 December 1947. Work was carried out along the entire line until Fauske, and for instance, the bridge across Finneidstrømmen was completed in 1947, ten years before the line was taken into use. Once the war was finished the investments on the line fell dramatically. The next stage, to Røkland, was not opened until 1 December 1955. With this a direct freight and passenger train operated north of Mo i Rana, while previously all trains had been locals terminating there. NSB's first diesel locomotive, Di 1 was used from Trondheim to Mo from 1953. The following year also Di 3 locomotives were used, which gradually were taken into use on more and more trains. The line was finished to Fauske on 1 December 1958. At the time it had a common station with the narrow-gauge Sulitjelma Line at Finneid Station.