Engineers in China have begun trial operations of the world’s biggest ship lift at the Three Gorges Dam, on the Yangtze River.
The elevator can be used by ships weighing up to 3000 tons.
The beginning of the trial operation marks the completion of the China Three Gorges Project, 22 years after construction began, said Zhang Shuguang, assistant general manager of the state-owned corporation responsible for the project.
The China Three Gorges Corporation says using the elevator cuts at least three hours off the time taken to traverse the lock system that sits alongside the dam.
Going up the wall
The elevator lifts ships directly up the wall of the dam which towers 175m above the water.
To use the elevator, the captain sails into its ship chamber which contains a pool of water 120m long, 18m wide and 3.5m deep. The chamber, the water in it and the lifting mechanisms weigh more than 15,500 tons. It takes around an hour for a ship to make the journey up or down the dam.
Concerns over safety
The elevator was built by a joint Chinese and German team, with designs being refined in the 24 years since the plan was first approved by the Chinese government in 1992.
According to Lu Youmei, former general manager of China Three Gorges Corporation, the original plan was to suspend the lifting chamber on steel cables. This plan was abandoned because of fears that the elevator could become unstable while lifting ships.
In 2003, Krebs and Kiefer, the German company involved in the design, introduced gear mechanisms instead of cables. This new design reassured the authorities that the system would be safe and work resumed on the elevator in 2008.
Navigating the upper Yangtze
Opening the upper reaches of the Yangtze River to shipping was a key target of the China Three Gorges project alongside flood control and power generation.
Before the dam was built, it was too dangerous for shipping to navigate the upper parts of Yangtze. The river was notorious for its winding, shallow and turbulent waters.