Photo taken on Dec. 28, 2020 shows the construction site of track-laying at a bridge of Lhasa-Nyingchi section of the Sichuan-Tibet Railway in southwest China`s Tibet Autonomous Region. The track-laying work was completed on Thursday for a railway linking the cities of Lhasa and Nyingchi in southwest China`s Tibet Autonomous Region. (Xinhua/Chogo)

Photo taken on Dec. 27, 2020 shows the construction site of track-laying at a tunnel of Lhasa-Nyingchi section of the Sichuan-Tibet Railway in southwest China`s Tibet Autonomous Region. The track-laying work was completed on Thursday for a railway linking the cities of Lhasa and Nyingchi in southwest China`s Tibet Autonomous Region. (Xinhua/Chogo)

Photo taken on Dec. 27, 2020 shows a bridge of Lhasa-Nyingchi section of the Sichuan-Tibet Railway in southwest China`s Tibet Autonomous Region. The track-laying work was completed on Thursday for a railway linking the cities of Lhasa and Nyingchi in southwest China`s Tibet Autonomous Region. (Xinhua/Chogo)

Photo taken on Dec. 31, 2020 shows the completion of track-laying of Lhasa-Nyingchi section of the Sichuan-Tibet Railway in southwest China`s Tibet Autonomous Region. The track-laying work was completed on Thursday for a railway linking the cities of Lhasa and Nyingchi in southwest China`s Tibet Autonomous Region. (Xinhua/Chogo)