National Geographic : 2017 Mar
0mi 1 0km 1 LOCK SYSTEM SHIP LIFT 40 minutes 4 hours Lift time: 21 minutes 0 1 million 2 million 2003 2015 2003 2015 0 60,000 120,000 Passenger traffic Cargo in metric tons CHINA TAIWAN Three Gorges Dam YangtzeYangtzeDAM Ship lift Reservoir Lock system 2. The Chamber Rises The chamber is made of reinforced concrete and is suspended from 256 cables attached to counterweights. When the counterweights go down, the chamber rises. COUNTERWEIGHTS Water can be added to or subtracted from the chamber to help raise or lower it. While gravity primarily powers the lift, electric motors are used to ensure its stability and safety, much like with an elevator. SAFETY MEASURES The ship chamber is accom- panied up and down by four static screws, called rotary locking rods. In the event of an accident, the screws, which follow threaded tracks, are locked and the chamber becomes immobile. 3. Exiting the Lift At the top of the lift, the chamber levels off with the water on the high side of the dam. A steel gate opens, and the vessel exits the chamber. EFFECT ON TRAFFIC Cargo traffic through the locks rose faster than expected after they opened in 2003, while passenger traffic declined. Other recent infrastructure projects, including the Yiwan Railway and the Hurong Expressway, offer faster routes for migrant workers through the Three Gorges region.