Abstract: The city of Guangzhou has proposed an urban spatial development strategy characterized by "advancing to the east, connecting with the west, expanding to the south, and optimizing in the north" in 2000. The initial target of this strategy was to form an urban spatial pattern of "two centers and four towns" in the city of Guangzhou by 2010. Later "adjusting in the central area" was added to the strategy to further optimize the layout of urban development, and to form a multi-center, clustering, and network type of urban spatial architecture by 2020.The implementation of this urban spatial development objective and the strategic adjustment require the essential support provided by the urban transport system, which demands higher quality development of the system. Urban transport infrastructure construction and the layout not only reflect the level of development of the city, but also are the important indicator and object of study and investigation of the differences in urban accessibility. With the development of urban transport in Guangzhou, especially the urban rail rapid transit (metro) network development in recent years, urban transport accessibility of the city has undergone significant changes, and also has an essential impact on and plays a key role in the structure and layout of urban spatial extension. In this context, this paper applies a grid-based partition method in a GIS (Geography Information System) environment to calculate the transportation infrastructure densities (including road density and bus line density) and analyze their spatial distribution. Moreover, this study measures the urban rail rapid transit network time-based accessibility based on matrix analysis and comprehensively investigates urban accessibility and its spatial characteristics in Guangzhou. The results show that the spatial pattern of urban accessibility in the city of Guangzhou is characterized by a concentric ring structure radiating outwards from the core area of the city. There are large regional variations between different areas in urban accessibility and the urban spatial pattern and structure of the city should be further improved and optimized. On the basis of multiple indicators, including time-based accessibility indices at each metro station and regional urban transport infrastructure densities, the study area is divided into different zones and the relationship between location and transportation accessibility is explored. At last, this paper integrates the spatial distributions and differences of urban public, commercial and residential facilities to further examine the characteristics and differentiation of urban spatial pattern in the city of Guangzhou, in order to provide scientific supports for the urban construction and spatial development.

Key words: accessibility, grid, Guangzhou, location, transportation infrastructures