The Hierarchy And Performance Of Spatial Structure In Metropolitan Area

It has been witnessed as a general tendency that metropolitan areas are enjoying more important positions in current urban system with rapid growth in their sizes. However, this kind of growth has brought about inefficiency of spatial structure such as unsatisfactory commute time, overdevelopment in downtown area s and underdevelopment in fringe areas, unbalanced distribution of urban green and public facilities, fragmented community environment and lost control resulting from low legibility over the whole area for urban residents. The cause of these problems lies in the "circular sprawl in the immediate areas", which leads to the unmatching of urban size and the urban spatial structure.The gradual increment in urban size will not result spontaneously in the reshaping of urban spatial structure. The thesis points out that the hierarchy of the urban spatial structure may influence its performance. There are two characteristics in the formation and evolvement of urban spatial structure: centripetence and fraction. The former strengthens the original summit central place whi le the latter enhance the fractal structures in lower hierarchies. The balanced point between these two tendencies depends on the effective organization of the hierarchy of urban spatial structure. The hierarchal organization in transportation modes is also related to the effectiveness of the hierarchy of urban spatial structure.The absence of middle-level urban spatial structure is the direct cause of the illegibility in the hierarchy of spatial structure. The middle -level urban spatial structure plays strategic role for spatial hierarchy and it has different modes in different locations. The empirical study of Singapore and Shanghai shows that the hierarchal organization of spatial structure should be considered in a systematic way. The essential control elements are further discussed.