Chinese engineers installed on Tuesday a key part of what will soon be the world's longest cross-sea bridge linking Hong Kong, Zhuhai and Macao.
The 6,000-tonne segment, 12 storeys tall and weighing more than 25 Airbus A380 jets, is part of a 5.7-kilometer underwater stretch of the Hong Kong-Zhuhai-Macao Bridge (HZMB).
Linking the two ends of the tunnel, the segment was placed 28 meters below the surface in a process that began at 5:00 a.m. and took almost 18 hours.
The undersea tunnel is located in the middle of the Hong Kong-Zhuhai-Macao Bridge.
World's largest crane ship at work
This was the most difficult part of building the main bridge body, with some describing it as "threading a needle under the sea." The process was carried out by Zhenhua 30, the world's largest crane ship, manufactured by China.
Water currents, wind, and buoyancy all played a role in the installation. Workers also had to proceed with caution given their tight margin of error of just 10 centimeters.
There are many methods to link the two ends of an undersea tunnel. Normally, it would take half a year to finish the process, but thanks to a new technique developed by Chinese engineers, the operation can now be done within 24 hours.
After the segment was put into place, it took another four to five hours to pump 2,500 tons of water out from the undersea tunnel to enable workers to get in. Fifteen days of welding work will now be needed before the tunnel is finally fully linked.
