Dozens of cities are building a metro system. Some do not need it … NOT many global cities of nearly 9m people lack an underground line, but until the end of last year the eastern city of Hangzhou was one of them. Now city slickers and rural migrants squeeze together inside shiny new carriages, checking their smartphones and reading free newspapers like commuters the world over. There is standing-room only in the rush hour and, with tickets at less than a dollar, the metro is revolutionising the way people travel across town. … Two other Chinese cities—Suzhou and Kunming—have also opened their first underground lines in the past year, and the north-eastern city of Harbin is preparing to open one too. Four more cities have just added a new line to their existing systems. At least seven others have begun building their first lines.