咸北線
In August 1980, Kim Il-sung ordered the construction of a new east-west transversal trunk line in the extreme north of the country. To accomplish this, railway engineers planned the new line, called the Pukpu Line, connecting Manp'o in the west with Hoeryŏng in the east to make use of parts of existing lines where possible to reduce the amount of new construction needed. Construction of this line was to take place in three stages. The first stage, completed in 1988, extended the former Unbong Line to Hyesan, resulting in the current Pukpu Line; the second stage was to have connected Hyesan to Musan on the Musan Line, and the third stage was to have connected Musan to Hoeryŏng on the Hambuk Line.