The existing line, running via Kangdŏk and the marshalling yard, was detached from the Hamgyeong Line and designated the Kangdŏk Line; at the same time, a 2 kilometers connection from Ch'ŏngjin Sŏhang Station (Ch'ŏngjin West Port, today called Songp'yŏng) to Kangdŏk was built, to allow southbound trains to access the marshalling yard without having to reverse at Ranam.