Technicians work on Altun Mountains in Ruoqiang County, northwest China's Xinjiang Uygur Autonomous Region, May 15, 2019. The 13.195-kilometer-long tunnel through Altun Mountains is the longest tunnel of the Golmud-Korla railway line. The railway line, connecting Golmud in Qinghai and Korla in Xinjiang, is the third rail artery linking Xinjiang with neighboring provinces. The line will cut the traffic time between Golmud and Korla from 26 hours to 12 hours. (Xinhua/Ding Lei)