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CREC4 finishes vault cover for worlds largest submarine tunnel2022-11-23 16:29:09

Constructors from China Railway No.4 Engineering Group Co., Ltd. (CREC4) completed building a key vault cover on November 20 for the world’s largest submarine tunnel in Qingdao, Shandong Province, creating a favourable condition for the subsequent construction for the covered caves.

The job is done by CREC4 Seventh Engineering Co., Ltd for the Jiaozhou Bay Second Tunnel, which will be 17.38 kilometers long, marking a new milestone in China’s engineering construction.


The 16-meter-long vault cover is completed on the NK4+836NK4+852 section of the tunnel’s No 2 Bid, and is done through concrete pouring.

The Jiaozhou Bay Second Tunnel, which will link the city’s main urban areas with its West Coast New District, will be constructed through drilling and blasting. As the world’s largest submarine tunnel in size, it is also a submarine tunnel in China that will witness the highest water pressure for the tunnel shields and deepest burial depth for blasts.

Since October, the CREC4 builders have sped up their construction process, showing a top speed of CREC4 in engineering construction.

The Jiaozhou Bay Second Tunnel, as a key project in Qingdao during the 14th Five-Year Plan period (2021-25) and a major artery in its “six horizontal and nine vertical” transport corridors in the city proper, will help boost traffic on both banks of Jiaozhou Bay, bolster the integration in the Jiaozhou Bay rim regions and enhance the high-standard opening-up of Qingdao.