In the 1970s, North Korea aimed to further develop the railways through the promotion of science and technology.
In the "Six-Year Plan for People's Economic Development" that started in 1971, Kim Il-sung, under the slogan "자력 갱생" (Charyŏk Kaengsaeng, "Self-Reliance"), declared that everything - economy, scientific advance, and development of industrial technology - should be made entirely domestically.
Though a considerable amount was achieved through domestic effort, a fair amount of the advances that were made came from foreign sources and were simply relabelled as North Korean.
The 1970s and 1980s can be considered as having been North Korea's "golden age", and though it did not last long, considerable successes in the development of the railways were achieved.

A great deal of attention was paid to developing urban transit in this period.
After the success of the P'yŏngyang trolleybus system opened in 1962, trolleybus services were inaugurated in  Ch'ŏngjin (1970), Hamhŭng (1973), Sinŭiju (1978), and Kowŏn (1979), Nampo (1982), P'yŏngsŏng (1983), Haeju (1986), Anju (1987), and others, along with the opening of the P'yŏngyang Metro in 1973; though most of the trolleybusses were built in North Korea to Czechoslovak and Soviet designs, the metro - despite claims of being entirely of domestic production - used mostly equipment supplied from China.
However, as at that time even Seoul had no subway system, its opening was proclaimed to be proof of the superiority of the socialist system.

Expansion and electrification of the national railway system continued as well.
New trunk lines were opened, such as the completion of the Ch'ŏngnyŏn Ich'ŏn Line on 10 October 1972, the completion of the Ch'ŏngnyŏn P'arwŏn Line, and the opening of shorter lines intended to serve new mines, power plants and factories, such as the Musan Kwangsan Line (1971), the Ch'ŏnghwaryŏk Line and the Namhŭng Line in 1976, the Sŏhae Kammun Line over the West Sea Barrage on 24 June 1986, and numerous other such lines.
Some major projects were initiated, such as the Pukpu Line which was to have been a new east-west transversal trunk line in the very north of the country, but were only partially completed: though work started in 1981, the first stage, from Manp'o to Hyesan was completed only in 1988, but further construction was suspended for over twenty years.
Regardless, the Sŏhae Kammun and Pukpu Line projects were the largest railway construction projects that the DPRK undertook entirely on its own.
As well as building new lines, several existing narrow gauge lines were converted to standard gauge, and by 1983, 927 km (576 mi) had been regauged.

The electrification of the P'yŏngra Line was finally completed in the 1970s; the project had been started at Yangdŏk in 1948 and completed in stages over the years following the Korean War, until the final section between Rajin and Ch'ŏngjin was energised in 1973.
With the electrification of the P'yŏngŭi Line in 1964 and the completion of the P'yŏngra Line project, both of the main trunk lines connecting P'yŏngyang with China and the USSR respectively, became fully electrified.
By the end of the 1970s, the goal of eliminating steam power from the primary trunk lines had been achieved, with nearly 87.5% of all railway movements being hauled by electric locomotives by the start of the 1980s, the total length of electrified standard gauge rail lines in North Korea reaching 3,940 km (2,450 mi); additionally, trackage within many industrial complexes was also electrified.

As electrification had become a national-level policy, Kukch'ŏl set out to develop new electric motive power.
Electric railcars had been used before the war by the Kŭmgangsan Electric Railway, and these were used by Kukch'ŏl until the line was destroyed during the Korean War, and no further electric railcars were used after that for many years.
However, the opening of the P'yŏngyang Metro, along with worldwide attention on high-speed electric trainsets such as the Japanese Bullet Train put into service in 1964 and the ER200 class introduced by the So
In the 1970s, North Korea aimed to further develop the railways through the promotion of science and technology. In the "Six-Year Plan for People's Economic Development" that started in 1971, Kim Il-sung, under the slogan "자력 갱생" (Charyŏk Kaengsaeng, "Self-Reliance"), declared that everything - economy, scientific advance, and development of industrial technology - should be made entirely domestically. Though a considerable amount was achieved through domestic effort, a fair amount of the advances that were made came from foreign sources and were simply relabelled as North Korean. The 1970s and 1980s can be considered as having been North Korea's "golden age", and though it did not last long, considerable successes in the development of the railways were achieved.
A great deal of attention was paid to developing urban transit in this period. After the success of the P'yŏngyang trolleybus system opened in 1962, trolleybus services were inaugurated in  Ch'ŏngjin (1970), Hamhŭng (1973), Sinŭiju (1978), and Kowŏn (1979), Nampo (1982), P'yŏngsŏng (1983), Haeju (1986), Anju (1987), and others, along with the opening of the P'yŏngyang Metro in 1973; though most of the trolleybusses were built in North Korea to Czechoslovak and Soviet designs, the metro - despite claims of being entirely of domestic production - used mostly equipment supplied from China. However, as at that time even Seoul had no subway system, its opening was proclaimed to be proof of the superiority of the socialist system.
Expansion and electrification of the national railway system continued as well. New trunk lines were opened, such as the completion of the Ch'ŏngnyŏn Ich'ŏn Line on 10 October 1972, the completion of the Ch'ŏngnyŏn P'arwŏn Line, and the opening of shorter lines intended to serve new mines, power plants and factories, such as the Musan Kwangsan Line (1971), the Ch'ŏnghwaryŏk Line and the Namhŭng Line in 1976, the Sŏhae Kammun Line over the West Sea Barrage on 24 June 1986, and numerous other such lines. Some major projects were initiated, such as the Pukpu Line which was to have been a new east-west transversal trunk line in the very north of the country, but were only partially completed: though work started in 1981, the first stage, from Manp'o to Hyesan was completed only in 1988, but further construction was suspended for over twenty years. Regardless, the Sŏhae Kammun and Pukpu Line projects were the largest railway construction projects that the DPRK undertook entirely on its own. As well as building new lines, several existing narrow gauge lines were converted to standard gauge, and by 1983, 927 km (576 mi) had been regauged.
The electrification of the P'yŏngra Line was finally completed in the 1970s; the project had been started at Yangdŏk in 1948 and completed in stages over the years following the Korean War, until the final section between Rajin and Ch'ŏngjin was energised in 1973. With the electrification of the P'yŏngŭi Line in 1964 and the completion of the P'yŏngra Line project, both of the main trunk lines connecting P'yŏngyang with China and the USSR respectively, became fully electrified. By the end of the 1970s, the goal of eliminating steam power from the primary trunk lines had been achieved, with nearly 87.5% of all railway movements being hauled by electric locomotives by the start of the 1980s, the total length of electrified standard gauge rail lines in North Korea reaching 3,940 km (2,450 mi); additionally, trackage within many industrial complexes was also electrified.
As electrification had become a national-level policy, Kukch'ŏl set out to develop new electric motive power. Electric railcars had been used before the war by the Kŭmgangsan Electric Railway, and these were used by Kukch'ŏl until the line was destroyed during the Korean War, and no further electric railcars were used after that for many years. However, the opening of the P'yŏngyang Metro, along with worldwide attention on high-speed electric trainsets such as the Japanese Bullet Train put into service in 1964 and the ER200 class introduced by the So
Korean State Railway