Work vessels help build an artificial island for the Shenzhen-Zhongshan Bridge in Shenzhen, South China's Guangdong Province in November 2018. Photo: VCG

The undersea tunnel of Shenzhen-Zhongshan Bridge, a mega project in the Guangdong-Hong Kong-Macao Greater Bay Area (GBA), has completed the sinking and docking of the E22 tube section on October 21.

It marked the installation of the last section of standard immersed tube and creating favorable conditions for the closure of the record-setting tunnel in 2023. 

The undersea tunnel is 6,845 meters in length, with the immersed tube section reaching 5,035 meters and consisting of 32 tube sections and one final joint, which is the longest and widest steel-cased concrete immersed tube tunnel in the world, per a statement issued by the local authority in South China's Guangdong Province on Saturday. 

The statement noted that a total of 31 immersed pipe sections have been installed currently with a total length of 4,867.8 meters, setting a new world record for the speed and accuracy of floating installation of largely immersed tubes.

The Shenzhen-Zhongshan Bridge connects Shenzhen and Zhongshan in Guangdong, a 24-km-long world-class cross-sea infrastructure project integrating "bridges, islands, tunnels, and underwater communications", according to the project's WeChat account. 

The completion of the project will reduce commute time between the two cities from 2 hours to 20 minutes, which is expected to complete in 2024 with an estimated 44.69-billion-yuan ($6.17 billion) investment. 

The construction of the project has entered its final sprint stage, and is advancing the fabrication and related work for the last tube section (E23) and the final joint, which is the world's first underwater push-out joint with an extreme difficulty and is scheduled to be installed in mid-2023.

The completion of the Shenzhen-Zhongshan Bridge will enable more efficient and convenient flow of capital, talent, technology, and other resource elements in the GBA, while further advancing the synergistic development of the city clusters and the one-hour living circle in the area is within reach.

The box girder installation of the Shenzhen-Zhongshan Bridge was completed on October 8. 

Global Times