Workers celebrate holing-through of Galashan Tunnel in Lhasa, SW China's Tibet

Workers work at the construction site of the Galashan Tunnel in Lhasa, southwest China's Tibet Autonomous Region, April 7, 2018. The 4,373-km-long tunnel, about 3,600 meters of altitude, is part of the Lhasa to Nyingchi railway. (Xinhua/Zhang Rufeng)