38 years ago today, on May 6, 1987 (April 9, 1987 lunar calendar), the Dayaoshan Tunnel, one of the world's top ten tunnels, was completed. The Dayaoshan Tunnel is located between Pingshi and Lechang on the Beijing-Guangzhou Railway Hengguang (Hengyang to Guangzhou) double line, passing through Dayaoshan Mountain from north to south. It is located in the territory of Lechang City, Guangdong Province, with a total length of 14.295 kilometers. It is currently the longest double-track electrified tunnel in China, and its length ranks tenth among the world's railway tunnels. The tunnel adopts the construction plan of "three oblique and one vertical". The 465-meter-long 9 #fault section passed through the middle of the tunnel has a maximum water inflow of 4,200 tons per day and night, which is the control area of the entire tunnel. The tunnel is fully constructed using the principle of the new Austrian method, with a maximum of 217 double-line meters of single-port single-head moon hole. Construction started in November 1981, and the tunnel was completed on May 6, 1987. It was completed in December 1989. Won the special prize of the National Science and Technology Progress Award.