 However, after a few years operating, many of these lines such as Guangzhou Metro Line 3, Line 6, Shanghai Metro Line 6, and Line 8 were severely overcapacity.Guangzhou Metro Line 3 was able to reconfigure from 3-car trains into 6-car trains to slightly relieve overcapacity.This led many cities such as Beijing, Guangzhou, Wuhan and Chengdu to use higher capacity designs on newer lines.