Dongting Lake is the second largest lake in China. It lies in the path of the Hangzhou-Ruili Highway. Whether this road can open to traffic or not depends on the successful completion of a giant suspension bridge across the lake.
The Second Dongting Lake Bridge has a span of 1,480 meters. It’s formed of two anchorages each exceeding 630,000 tons in weight, two pylons rising over 200 meters, two 2,600-meter-long main cables and a deck formed of over 43,000 tons of steel truss girders. The anchorages and towers have been completed, and engineers must now start the most crucial part of the project – the installation of the main cables.
These cables need to support the 40,000-ton deck throughout the bridge’s estimated 100-year lifetime. For a 1,480-meter-long bridge, the main cables must be made to the highest possible production standards. 760 kilometers away, Wuxi, Jiangsu, is the place where the vital steel wires forming the cables are produced.
The steel rod has a maximum tensile strength of 1,860 MPa. No reduction in this strength is permitted, throughout the 200 meters the steel wires are being reduced in diameter. The wire is steeped in a metallic liquid at 450 degrees Celsius, and it’s coated with a thin anti-corrosive that will protect it from adverse environmental conditions for 100 years.
In the cable strand production workshop, there are 127 distribution frames. Each steel wire will follow a unique route to the assembly area. After that all 127 strands will eventually meet at the convergence frame, and be bundled to make a hexagonal cable.
Each steel wire will have its unique position on the bridge. Every one of the 172 hexagonal strands is formed of 127 wires. This is how the key cables are made so that each of them is capable of bearing a 90,000-ton load. After six hours of work, a 2,600-meter-long cable strand has been completed.
This meticulous work, all made in China, ensures that a state-of-the-art infrastructure will be made successfully and of the best quality.