Construction workers of China Railway 14th Bureau Group Co., Ltd. check the "Yongping" shield tunneling machine with an excavation diameter of 14.57 meters, in Shantou City, south China's Guangdong Province, on March 26, 2025. The Shantou Bay undersea tunnel, the world's first single-hole double-track undersea tunnel with a designed speed of 350 km per hour, was broken through on Wednesday. The 9,781-meter-long tunnel is a project of the Shantou-Shanwei high-speed railway. (Xinhua/Liu Dawei)。

Construction workers of China Railway 14th Bureau Group Co., Ltd. work on the "Yongping" shield tunneling machine with an excavation diameter of 14.57 meters, in Shantou City, south China's Guangdong Province, on March 26, 2025. The Shantou Bay undersea tunnel, the world's first single-hole double-track undersea tunnel with a designed speed of 350 km per hour, was broken through on Wednesday. The 9,781-meter-long tunnel is a project of the Shantou-Shanwei high-speed railway. (Xinhua/Liu Dawei)。

This photo taken on 吃瓜網(wǎng)91March 25, 2025 shows the construction site of the Shantou Bay undersea tunnel in Shantou City, south China's Guangdong Province. The Shantou Bay undersea tunnel, the world's first single-hole double-track undersea tunnel with a designed speed of 350 km per hour, was broken through on Wednesday. The 9,781-meter-long tunnel is a project of the Shantou-Shanwei high-speed railway. (Xinhua/Liu Dawei)。

The "Yongping" shield tunneling machine with an excavation diameter of 14.57 meters, advances to the submarine breakthrough point of Shantou Bay, in Shantou City, south China's Guangdong Province, on March 26, 2025. The Shantou Bay undersea tunnel, the world's first single-hole double-track undersea tunnel with a designed speed of 350 km per hour, was broken through on Wednesday. The 9,781-meter-long tunnel is a project of the Shantou-Shanwei high-speed railway. (Xinhua/Liu Dawei)。

This photo taken on 黑料吃瓜在線March 25, 2025 shows the construction site of the Shantou Bay undersea tunnel in Shantou City, south China's Guangdong Province. The Shantou Bay undersea tunnel, the world's first single-hole double-track undersea tunnel with a designed speed of 350 km per hour, was broken through on Wednesday. The 9,781-meter-long tunnel is a project of the Shantou-Shanwei high-speed railway. (Xinhua/Liu Dawei)。

This photo taken on 每日吃瓜今日大瓜March 25, 2025 shows the construction site of the Shantou Bay undersea tunnel in Shantou City, south China's Guangdong Province. The Shantou Bay undersea tunnel, the world's first single-hole double-track undersea tunnel with a designed speed of 350 km per hour, was broken through on Wednesday. The 9,781-meter-long tunnel is a project of the Shantou-Shanwei high-speed railway. (Xinhua/Liu Dawei)。

This photo taken on March 26, 2025 shows the U-shaped subgrade section of the Shantou Bay undersea tunnel in Shantou City, south China's Guangdong Province, on March 26, 2025. The Shantou Bay undersea tunnel, the world's first single-hole double-track undersea tunnel with a designed speed of 350 km per hour, was broken through on Wednesday. The 9,781-meter-long tunnel is a project of the Shantou-Shanwei high-speed railway. (Xinhua/Liu Dawei)。

A construction worker from China Railway 14th Bureau Group Co., Ltd. checks the tool abrasion of the "Yongping" shield tunneling machine, in Shantou City, south China's Guangdong Province, on March 26, 2025. The Shantou Bay undersea tunnel, the world's first single-hole double-track undersea tunnel with a designed speed of 350 km per hour, was broken through on Wednesday. The 9,781-meter-long tunnel is a project of the Shantou-Shanwei high-speed railway. (Xinhua/Liu Dawei)。

This photo taken on March 26, 2025 shows the Shantou Bay undersea tunnel in Shantou City, south China's Guangdong Province. The Shantou Bay undersea tunnel, the world's first single-hole double-track undersea tunnel with a designed speed of 350 km per hour, was broken through on Wednesday. The 9,781-meter-long tunnel is a project of the Shantou-Shanwei high-speed railway. (Xinhua/Liu Dawei)。

The "Yongping" shield tunneling machine with an excavation diameter of 14.57 meters, advances to the submarine breakthrough point of Shantou Bay, in Shantou City, south China's Guangdong Province, on March 26, 2025. The Shantou Bay undersea tunnel, the world's first single-hole double-track undersea tunnel with a designed speed of 350 km per hour, was broken through on Wednesday. The 9,781-meter-long tunnel is a project of the Shantou-Shanwei high-speed railway. (Xinhua/Liu Dawei)。