Workers celebrate the holing through of the Milin tunnel, a key project in the Lhasa-Nyingchi section of the Sichuan-Tibet Railway in southwest China's Tibet autonomous region, April 7, 2020. Construction of the Sichuan-Tibet Railway, the second railway to go into Tibet, has been making steady progress. Recently, 47 tunnels along the Lhasa-Nyingchi section of the railway have been bored, laying a solid foundation for the operation of the section. (Photo/Jue Guo)