 There are two series of ship locks installed near the dam ( 30 ° 50 ′ 12 ″ N 111 ° 1 ′ 10 ″ E ) . Each of them is made up of five stages , with transit time at around four hours . Maximum vessel size is 10 @,@ 000 tons . The locks are 280 m long , 35 m wide , and 5 m deep ( 918 × 114 × 16 @.@ 4 ft ) . That is 30 m longer than those on the St Lawrence Seaway , but half as deep . Before the dam was constructed , the maximum freight capacity at the Three Gorges site was 18 @.@ 0 million tonnes per year . From 2004 to 2007 , a total of 198 million tonnes of freight passed through the locks . The freight capacity of the river increased six times and the cost of shipping was reduced by 25 % . The total capacity of the ship locks is expected to reach 100 million tonnes per year . 
