North Korea Pyongyang subway engineering survey, measurement

North Korea Pyongyang subway in China in 1968 began a free aid, total length of 35 kilometers, a total of 17 stations.

Pyongyang subway known as the world's deepest subway system, the deepest underground 150m, the average depth of 90m. From the ground by the escalator to the site takes 3 minutes. This was not the high level of mechanization of the Chinese Railway Corps troops, the construction is very difficult.