Research on accessibility pattern of China at city level based on land traffic network

In order to make a quantitative study about accessibility of cities in China, the spatial analyst module functions of ARCGIS were mainly used to do an empirical research about it based on land traffic network structure and calculations of optimal road routes and time to cities of China, which generated accessibility diffusion graph and average accessibility graph of cities. And then, the ESDA was analyzed by indexes such as Moran's I, Local Moran's I and Getis-Ord Gi* used to measure spatial pattern of the average accessibility of China at city level. The results showed that the overall accessibility of China is 3.37h and as to the regional accessibility, 26.89% and 51.26% of cities are within 1h and 2h. However, the internal difference of accessibility is obvious. The accessibility of cities in the east and middle of China was good, while it was much worse in the west of Inner Mongolia and the boundary area between Xinjiang, Xizang and Qinghai, especially the Qinghai-Tibet plateau region. The overall degree of agglomeration of the average accessibility at city level was quite low and the index of Moran's I is only about 0.09. The hot spot regions were mainly distributed in the east and middle of China as well as Sichuan, Yunnan, Guizhou, Shanxi, Gansu and Ningxia, while the sub-hot regions in the boundary areas between the west and the middle part of China. In addition, the outlying areas of Inner Mongolia, Xinjiang, and Xizang are sub-cold, while the cold spot regions are distributed in the Qinghai-Tibet plateau region. Finally, on the basis of above, some factors influencing the accessibility of cities such as the position of seat of the government, the size of cities, the structure of traffic, natural environment and economic conditions, were summed up in the paper. The former three factors were the immediate causes and the latter two were indirect causes.