China’s engineering miracle: a new underwater tunnel cuts travel time in half

China's engineering miracle: a new underwater tunnel cuts travel time in half

China’s high-speed rail network continues to gain momentum with the completion of a record-breaking underwater tunnel. The underwater tunnel across the Zhanjiang Bay, a key section of the Guangzhou-Zhanjiang high-speed railway, marks a major milestone in the country’s infrastructure development.

After 33 months of construction, the tunnel boasts an impressive length of 9,640 meters, of which 7,551 meters were bored by a single tunnel boring machine (TBM) called Yongxing. This makes it the longest single-slope underwater high-speed rail shield tunnel in China, demonstrating the country’s remarkable engineering expertise.

The importance of this single-pass approach lies in its efficiency and safety, especially when working in difficult geological conditions. Traditional methods, which involve excavating the TBM on both sides and meeting in the middle, were found to be unsuitable for the Zhanjiang Bay project.

Imagine this behemoth burrowing up to 50 meters underwater, withstanding enormous pressure equivalent to 5.2 kilograms per fingernail-sized area. No wonder the team of the 14th group of the Chinese Railway Bureau had to adapt the machine specifically for these difficult conditions!

But why a tunnel and not a bridge? The answer to this question is multifaceted. The tunnel protects the picturesque skyline of Zhanjiang Bay and minimizes the environmental impact on marine life. In addition, a bridge can impede the passage of large ships and be vulnerable to typhoons, which often occur in this area. The underwater tunnel bypasses these problems, providing uninterrupted and safe high-speed rail service even in severe weather conditions.

This important tunnel paves the way for the completion of the entire 401-kilometer Guangzhou-Zhanjiang high-speed rail line by the end of 2025. With a design speed of 350 kilometers per hour, this rail line is a vital addition to China’s high-speed network. Once operational, travel time between Guangzhou and Zhanjiang will be reduced from over 2.5 hours to 90 minutes. This project will undoubtedly contribute to the qualitative development of the entire region.


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