Constructors work at the construction site of Zhaowan Tunnel of Lanzhou-Hezuo high-speed railway in Linxia Hui Autonomous Prefecture, northwest China's Gansu Province, June 6, 2025. The Zhaowan Tunnel, with a total length of 1642.35 meters and a relative height difference of 370 meters, was drilled through on Friday. The tunnel is a key project of Lanzhou-Hezuo high-speed railway, a part of China's high-speed rail network that centers around eight main vertical lines linking the north and south and eight horizontal lines connecting the east and west. (Xinhua/Chen Bin)

Constructors work at the construction site of Zhaowan Tunnel of Lanzhou-Hezuo high-speed railway in Linxia Hui Autonomous Prefecture, northwest China's Gansu Province, June 6, 2025. The Zhaowan Tunnel, with a total length of 1642.35 meters and a relative height difference of 370 meters, was drilled through on Friday. The tunnel is a key project of Lanzhou-Hezuo high-speed railway, a part of China's high-speed rail network that centers around eight main vertical lines linking the north and south and eight horizontal lines connecting the east and west. (Xinhua/Chen Bin)

An aerial drone photo taken on June 6, 2025 shows the Zhaowan Tunnel of Lanzhou-Hezuo high-speed railway in Linxia Hui Autonomous Prefecture, northwest China's Gansu Province. The Zhaowan Tunnel, with a total length of 1642.35 meters and a relative height difference of 370 meters, was drilled through on Friday. The tunnel is a key project of Lanzhou-Hezuo high-speed railway, a part of China's high-speed rail network that centers around eight main vertical lines linking the north and south and eight horizontal lines connecting the east and west. (Xinhua/Chen Bin)

An aerial drone photo taken on June 6, 2025 shows the Zhaowan Tunnel of Lanzhou-Hezuo high-speed railway in Linxia Hui Autonomous Prefecture, northwest China's Gansu Province. The Zhaowan Tunnel, with a total length of 1642.35 meters and a relative height difference of 370 meters, was drilled through on Friday. The tunnel is a key project of Lanzhou-Hezuo high-speed railway, a part of China's high-speed rail network that centers around eight main vertical lines linking the north and south and eight horizontal lines connecting the east and west. (Xinhua/Chen Bin)

A constructor walks at the construction site of Zhaowan Tunnel of Lanzhou-Hezuo high-speed railway in Linxia Hui Autonomous Prefecture, northwest China's Gansu Province, June 6, 2025. The Zhaowan Tunnel, with a total length of 1642.35 meters and a relative height difference of 370 meters, was drilled through on Friday. The tunnel is a key project of Lanzhou-Hezuo high-speed railway, a part of China's high-speed rail network that centers around eight main vertical lines linking the north and south and eight horizontal lines connecting the east and west. (Xinhua/Chen Bin)

Constructors work at the construction site of Zhaowan Tunnel of Lanzhou-Hezuo high-speed railway in Linxia Hui Autonomous Prefecture, northwest China's Gansu Province, June 6, 2025. The Zhaowan Tunnel, with a total length of 1642.35 meters and a relative height difference of 370 meters, was drilled through on Friday. The tunnel is a key project of Lanzhou-Hezuo high-speed railway, a part of China's high-speed rail network that centers around eight main vertical lines linking the north and south and eight horizontal lines connecting the east and west. (Xinhua/Chen Bin)

Constructors pose for a group photo at the construction site of Zhaowan Tunnel of Lanzhou-Hezuo high-speed railway in Linxia Hui Autonomous Prefecture, northwest China's Gansu Province, June 6, 2025. The Zhaowan Tunnel, with a total length of 1642.35 meters and a relative height difference of 370 meters, was drilled through on Friday. The tunnel is a key project of Lanzhou-Hezuo high-speed railway, a part of China's high-speed rail network that centers around eight main vertical lines linking the north and south and eight horizontal lines connecting the east and west. (Xinhua/Chen Bin)