The trial operation of the permanent shiplift at the Three Gorges Dam in central China's Hubei Province began Sunday, marking the completion of the Three Gorges project 22 years after construction began.

The shiplift, designed by a Chinese and German team, is the largest and most sophisticated in the world, according to the China Three Gorges Corp., a state-owned company responsible for the construction of the Three Gorges project.

The vertical-hoisting elevator is designed to help small and medium-sized ships, with a maximum displacement of about 3,000 tonnes, to traverse the dam. The water level behind the dam is up to 113 meters higher than the downstream river.

The shiplift is equipped with a ship-chamber, which has a pool of water 120-meters long, 18-meters wide and 3.5-meters deep. The chamber, its mechanical systems and the water weigh 15,500 tonnes altogether.

The shiplift has been installed to complement the five-tier ship lock next to it, which is also the world's largest and has allowed ships to pass through since 2003. The ship lock is running at full capacity, with its cargo throughput standing at 119.6 million tonnes in 2015, compared with 34.31 million tonnes in 2004. The increase has been attributed to the booming water transportation sector along the mountainous regions of the Three Gorges, including the southwestern municipality of Chongqing.

It used to take ships about three to four hours to pass the dam via the ship lock. The shiplift will cut this time to about 40 minutes to one hour.

PERIOD PROJECT

The Three Gorges project is a multi-functional water control system, consisting of a 2,309-meter long and 185-meter high dam, a five-tier ship lock, 32 hydropower turbo-generators and a shiplift.

The shiplift was in the original plan that was passed by the National People's Congress, China's top legislature, in 1992. But due to technical and safety concerns, the shiplift project was put on hold in 1994.

By the end of 2009, all the construction work at the dam had been done except for the shiplift, which has been lauded for "bringing the last mystery of the Three Gorges project into the light."

The original plan was to build a wire rope hoist shiplift. Experts, however, were concerned about its colossal scale, and the tank used to carry ships would be unstable, said Lu Youmei, former general manager of China Three Gorges Corp.

In 2003, gear-rack driven mechanisms and nut-screw safety measures from Germany were introduced to replace the original plan. These new systems were approved by the Three Gorges Construction Committee under the State Council, China's cabinet. Construction resumed in 2008.

This new approach was adopted as it would help keep the shiplift balanced, and it is far more superior to the wire rope hoist method, said Lu, who is also an academic with the Chinese Academy of Engineering.

Over the past eight years, many advances have been made, new standards had been released for steel smelting, civil engineering and management, thanks to the construction of the shiftlift, said Wu Xiaoyun, deputy director of the mechanical and electrical engineering department under the Three Gorges Corp., who headed the shiplift project.

UTILIZATION EFFICIENCY

Boosting the shipping capacity of the Yangtze, China's longest river, was one of the three major functions of the Three Gorges project besides flood control and power generation.

Before measures to store water in the Three Gorges reservoir in 2003, the upper reaches of the Yangtze River were off-limits to big vessels as the river was too narrow and shallow, while its many winding and turbulent stretches were called "ghost gates" that were very dangerous for small boats.

The dam greatly improved the navigation on the river by lifting water levels on the upper reaches and releasing storage of flood waters to supply the middle-lower reaches during the dry season.

According to the Three Gorges Navigation Authority, as many as 150 cargo ships, carrying more than 300,000 tonnes of goods, passed through the ship lock every day in 2015, more than eight times of that in 2003 when it opened.

The demands for river transportation are likely to grow as China made the Yangtze River economic belt a focus of its national strategy in 2014 to boost concerted development in riverside provinces and municipalities.

The shiplift, however, was originally designed to mainly serve passenger and emergency cargo ships, as passenger transport was still popular on the Yangtze River at the time.

As a result of the rapid development of highways and high-speed rail across the country, hardly anyone would choose the slow waterway to get to those regions.

The shiplift would function as a good supplement to the already crammed ship lock, allowing smaller and more urgent cargo ships to pass the dam with less waiting time, according to the navigation authority.

In the meantime, the authority is making other efforts to raise the utilization efficiency of the shiplift.

"We are coordinating with transport authorities to introduce new ship standards that can fit in the shiplift, and discussing with travel agencies to design targeted products for those who are interested," said a senior official with the navigation authority. "The shiplift would add new flavor and experience to the classic Three Gorges tour."