World's Longest Single-Span Suspension Bridge Achieves Major Milestone as Pilot Cable Crosses Sea

The Ningbo Zhoushan Port Liuheng Highway Bridge Phase II project, built by CRCC, reached a significant construction milestone on December 6. The pilot cable for the Shuangyumen Bridge, the project's key structure, was successfully installed across the sea, marking the official launch of catwalk construction and laying the groundwork for subsequent installation of traction cables and load-bearing cables.

With a main span of 1,768 meters, the Shuangyumen Bridge is currently the world's longest single-span suspension bridge featuring a steel box girder and China's longest sea-crossing bridge. The successful installation of the pilot cable-the first critical step in constructing the bridge's superstructure-plays a fundamental and decisive role in organizing the overall construction and advancing subsequent work.

At 9 a.m. on the day of installation, a DJI FlyCart 100 heavy-lift drone took off from the main tower on the Fodu side under unified site coordination. Carrying a pilot cable measuring approximately 2,100 meters in length, 2.5 millimeters in diameter, and weighing about 8.4 kilograms, the drone followed a predetermined flight path across the waterway. Despite challenging navigation conditions and maritime weather, the drone reached its target at the Liuheng-side main tower in approximately 12 minutes, successfully completing the cross-sea operation and precisely connecting the two main towers with support from coordinating departments.

The project team conducted extensive technical assessments and compared multiple approaches, evaluating factors including safety, controllability, construction efficiency, and cost. They ultimately selected this innovative heavy-lift drone method, which circumvents the navigational constraints of traditional vessel-towing or rocket-projection methods while improving operational precision and construction efficiency.

Once completed, the Ningbo Zhoushan Port Liuheng Highway Bridge Phase II project will enhance the integrated sea-land transportation network of Ningbo Zhoushan Port, ease cross-sea traffic congestion between Liuheng Island and the mainland and surrounding islands, and provide crucial support for regional industrial coordination and high-quality marine economic development.