The massive new ship lift being used at the Three Gorges Dam on the Yangtze River, the biggest and highest one in the world, has greatly boosted efficiency and safety for ships going through the dam, said the head of its operations.

The ship lift, which began functioning in September, can elevate vessels up to 3,000 metric tons up or down a vertical distance of 113 meters. The ship chamber itself has a pool of water 120 meters long by 18 meters wide and 3.5 meters deep. The lift was built to accommodate mostly small and medium-sized vessels, with bigger ships still using the dam's adjacent five-tiered lock system to navigate the waterway.

"It only takes about 40 minutes for a ship to go through the dam compared with around three hours in the past," said Wu Xiaoyun, director of the ship lifter program and chief of the electromechanical engineering bureau of China Three Gorges Corp.

Before the completion of the ship lift, all the ships had to use the five levels of ship locks.

"Ship locks were like stairs. Walking up or down stairs is certainly much slower than taking the lift," Wu said.

The ship lift is the biggest in the world with maximum lifting weight of 15,500 tons and maximum height of 113 meters.

The new ship lift entered the second phase of its trials when it began operating 24 hours a day in November, following its successful first tests in September.

"Apart from faster speed, the ship lift is also safer. It's very dangerous if the ship catches fire in ship locks. But on the lift, with its open space, the chance for such a situation developing is much smaller," said Wu.

He said one of the biggest challenges in building the ship lift was a potential swelling of the cement towers under the heat of the sun, which could tilt the lift.

In order to indicate that a strict balance for a ship was achieved as it was lifted, a coin was placed standing upright on the railing of the vessel during the test run. The coin remained upright throughout the process.

Wu said the balance of a ship could also be effected if the unit's wheels for lifting the ship were to crack. To establish beyond doubt that the wheels are solid, they are subjected to exhaustive testing which concluded that they are good for at least 70 years.

The ship lift was completely made by China－the design, the equipment manufacturing, the installation and construction, said Wu.

Contact the writers at [email protected] and [email protected]