BUILDING THE THREE GORGES DAM by releasing the water through a contained and controlled process , but also enabled economic growth . It receives over 150 freight ships per day over the Yangtze river - the biggest ship locks in the world were constructed here in order to cater for the predicted 100 million tonnes which will cross the river annually . As ships become enclosed by staircases and inner gate locks within the two different ship locks , water lifts the ships either upwards or downwards through five tiers in around four hours . Through these ship locks , freight capacity has increased significantly , in addition to the reduction of shipping by 20 percent , therefore increasing its economic and environmental appeal .
For passenger boats , however , the time taken to reach the top is minimised through the use of a ship lift , which acts as an elevator to allow boats to reach the top in just
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