Beijing now has about 20 million people. Shanghai (greater area) is at 29 million and greater Guangzhou is 32 million.
Ring Road growth Rings
The fourth ring road was completed in 2001.
The Fifth ring road was completed between 2003-2005.
The sixth ring road was open for regular traffic in September 12, 2009.
Construction began on the seventh ring road in 2013
The ring roads and subway systems get expanded and homes and offices fill out the expanded area.
Son V. Nghiem (JPL) has a presentation
Journal of Geophysical Research - Ring of impact from the mega-urbanization of Beijing between 2000 and 2009
A team led by Mark Jacobson of Stanford University, Palo Alto, California, and Son Nghiem of NASA's Jet Propulsion Laboratory, Pasadena, California, used data from QuikScat to measure the extent of infrastructure changes, such as new buildings and roads, in China's capital. They then quantified how urban growth has changed Beijing's wind patterns and pollution, using a computer model of climate and air quality developed by Jacobson.
New infrastructure alone—the buildings and roads themselves, not including additional pollution created by the new city dwellers and their vehicles—created a ring of impacts around the older parts of Beijing. The impacts included increasing winter temperatures by about 5 to 7 degrees Fahrenheit (3 to 4 degrees Celsius) and reducing wind speed by about 2 to 7 mph (1 to 3 meters per second), making the city air more stagnant.
Shanghai has physically merged with nearby cities into a megacity