It has taken 8 years to create this 6.7 km tunnel, immersed on 5.6 km, connecting the cities of Hong Kong, Zhuhai and Macao, crossing the sea of Ling Ding Yang at the Pearl River Delta of South China. The tunnel was assembled with 33 elements of 180m in length, 11.4m in height and 37.95m in width, for a weight of 80,000 tons. Those are the world’s largest tunnel elements. Artificial islands have been created at the both ends of the tunnel to connect it to the bridges. This bridge link is 45m under the sea, to allow passage of 300,000 DWT tankers. This is one of the deepest immersed tunnels in the world.
Some innovative techniques have been used to build this tunnel. Due to delicate geological conditions, the foundations of the immersed tunnel have been mixed between rigid and soft ones. This resulted in the use of Pre-stressed High Strength Concrete piles, Jet grouting piles, Sand Compaction Piles, Compacted Block Stone plus Gravel Bed Foundation to create optimum foundation conditions. This is also the first tunnel in the world where curved tunnel elements have been prefabricated, improving many technologies to measure what size was necessary. To conclude, the final section of the immersed tunnel, the so-called closure joint is an innovation in a “V shape” and of a sandwich structure (steel box structure filled with high fluid concrete) as the basic structure.