Photo taken on Dec. 23, 2018 shows a construction site on the Lhasa-Nyingchi section of the Sichuan-Tibet Railway in southwest China's Tibet Autonomous Region. The Sichuan-Tibet Railway will be the second railway into southwest China's Tibet Autonomous Region after the Qinghai-Tibet Railway. The line will go through the southeast of the Qinghai-Tibet Plateau, one of the world's most geologically active areas. (Xinhua/Purbu Zhaxi)

Workers are seen at a construction site on the Lhasa-Nyingchi section of the Sichuan-Tibet Railway in southwest China's Tibet Autonomous Region, Dec. 23, 2018. (Xinhua/Chogo)

Workers are seen at a construction site of the Yarlung Zangbo River bridge on the Lhasa-Nyingchi section of the Sichuan-Tibet Railway in Gonggar of southwest China's Tibet Autonomous Region, Dec. 22, 2018. (Xinhua/Wang Quanquan)

Workers are seen at a construction site of the Yarlung Zangbo River bridge on the Lhasa-Nyingchi section of the Sichuan-Tibet Railway in Gonggar of southwest China's Tibet Autonomous Region, Dec. 22, 2018. (Xinhua/Wang Quanquan)

Workers are seen at a construction site on the Lhasa-Nyingchi section of the Sichuan-Tibet Railway in southwest China's Tibet Autonomous Region, Dec. 23, 2018. (Xinhua/Chogo)

Workers are seen at a construction site on the Lhasa-Nyingchi section of the Sichuan-Tibet Railway in southwest China's Tibet Autonomous Region, Dec. 23, 2018. The Sichuan-Tibet Railway will be the second railway into southwest China's Tibet Autonomous Region after the Qinghai-Tibet Railway. (Xinhua/Purbu Zhaxi)

Workers are seen at a construction site of the Yarlung Zangbo River bridge on the Lhasa-Nyingchi section of the Sichuan-Tibet Railway in Gonggar of southwest China's Tibet Autonomous Region, Dec. 22, 2018. (Xinhua/Wang Quanquan)

Photo taken on Dec. 23, 2018 shows a construction site on the Lhasa-Nyingchi section of the Sichuan-Tibet Railway in southwest China's Tibet Autonomous Region. (Xinhua/Chogo)

Workers are seen at a construction site on the Lhasa-Nyingchi section of the Sichuan-Tibet Railway in southwest China's Tibet Autonomous Region, Dec. 23, 2018. (Xinhua/Chogo)