Evaluating cities' vitality and identifying ghost cities in China with emerging geographical data

With the rapid urbanization of China, plenty of new urban lands have been developed with the great expectation to deal with all kinds of issues in old urban areas such as high population density, great demand on limited land resources, and decaying environment. However, a great proportion of vacancy in these newly developed units leads to the undesired observation of ghost cities. Lacking of clear and effectively evaluation criterion, the understanding of ghost cities in China is then rather limited. Considering the fact of ghost cities, we borrow the theory of urban vitality to identify and evaluate ghost cities in this paper. We argue that ghost cities are associated with very low urban vitality. In the light of big/open data, we are able to profile ghost cities of China based on 535,523 recent project-level residential developments from 2002 to 2013. We use the national-wide and million magnitude road junctions, points of interest and location based service records of 2014/2015 for measuring the morphological, functional and social vitality of each residential project. We then aggregate the project level evaluation results into the city level and thirty ghost cities are then identified by comparing the residential projects' vitality in the old (developed before or in 2000) and new (developed after 2000) urban areas in each city. Our profiling results illustrate the big picture of China's past residential developments, and then of ghost cities. We find the average vitality of residential projects in new urban areas is only 8.8% of that in old urban areas, denoting the potential existence of ghost cities in newly developed areas in Chinese cities. We have also benchmarked our identified ghost cities with existing rankings, the Baidu searching engine and night-time light images. Although we admit that ghost cities may exist in the particular urbanizing phase of China and that some ghost cities now may be well developed in the future, this study provides a thorough evaluation on the ghost city condition in China. This may shed light on policy implications for Chinese urban development.