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)