Urban Three-dimensional Expansion and Its Driving Forces —A Case Study of Shanghai, China 
SHI Longyu, SHAO Guofan, CUI Shenghui, LI Xuanqi, LIN Tao, YIN Kai, ZHAO Jingzhu
Urban three-dimensional expansion and its driving forces—a case study of Shanghai, China
    Urban expansion is a phenomenon of urban space increase, and an important measuring index of the process of urbanization. Taking Shanghai as an example, the changes of urban average height and built-up area were studied to represent city's vertical and horizontal increases respectively, and statistical methods were used to analyze the driving forces  of  urban  expansion.  The  research  drew  following  conclusions:  1)  The  urban  expansion  process  of  Shanghai from 1985 to 2006 had a clear periodic feature, and could be divided into three stages: vertical expansion in dominance, coordinated  vertical  and  horizontal  expansion,  and  horizontal  expansion  in  dominance.  2)  The  average  height  and quantity of buildings in core city were significantly bigger than those in suburbs, but the changing speed of the latter was faster. And 3) urbanization process was the major driving force for the city's horizontal expansion, while industrial structure improvement was the key driving factor for the vertical expansion. Those two driving forces were simultane-ously affected by city's political factors.