Technicians from China Railway Electrification Engineering Group work at the construction site of the power supply system of Lhasa-Nyingchi railway in Mainling County of Nyingchi, southwest China`s Tibet Autonomous Region, April 8, 2020. The 435-km-long Lhasa-Nyingchi railway, with a designed speed of 160 km per hour, is the first electric railway in Tibet. (Xinhua/Chogo)

Technicians from China Railway Electrification Engineering Group work at the construction site of the power supply system of Lhasa-Nyingchi railway in Mainling County of Nyingchi, southwest China`s Tibet Autonomous Region, April 8, 2020. The 435-km-long Lhasa-Nyingchi railway, with a designed speed of 160 km per hour, is the first electric railway in Tibet. (Xinhua/Chogo)

Technicians from China Railway Electrification Engineering Group work at the construction site of the power supply system of Lhasa-Nyingchi railway in Mainling County of Nyingchi, southwest China`s Tibet Autonomous Region, April 8, 2020. The 435-km-long Lhasa-Nyingchi railway, with a designed speed of 160 km per hour, is the first electric railway in Tibet. (Xinhua/Chogo)

Technicians from China Railway Electrification Engineering Group work at the construction site of the power supply system of Lhasa-Nyingchi railway in Mainling County of Nyingchi, southwest China`s Tibet Autonomous Region, April 8, 2020. The 435-km-long Lhasa-Nyingchi railway, with a designed speed of 160 km per hour, is the first electric railway in Tibet. (Xinhua/Chogo)

Technicians from China Railway Electrification Engineering Group work at the construction site of the power supply system of Lhasa-Nyingchi railway in Mainling County of Nyingchi, southwest China`s Tibet Autonomous Region, April 8, 2020. The 435-km-long Lhasa-Nyingchi railway, with a designed speed of 160 km per hour, is the first electric railway in Tibet. (Xinhua/Chogo)

Technicians from China Railway Electrification Engineering Group work at the construction site of the power supply system of Lhasa-Nyingchi railway in Mainling County of Nyingchi, southwest China`s Tibet Autonomous Region, April 8, 2020. The 435-km-long Lhasa-Nyingchi railway, with a designed speed of 160 km per hour, is the first electric railway in Tibet. (Xinhua/Chogo)

Technicians from China Railway Electrification Engineering Group work at the construction site of the power supply system of Lhasa-Nyingchi railway in Mainling County of Nyingchi, southwest China`s Tibet Autonomous Region, April 8, 2020. The 435-km-long Lhasa-Nyingchi railway, with a designed speed of 160 km per hour, is the first electric railway in Tibet. (Xinhua/Chogo)