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Data Mining Reveals the Extent of China's Ghost Cities

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A map of largely vacant residential areas in China.

Researchers at Chinese search engine Baidu have performed a scientific study of China's ghost cities.

Credit: Technology Review

China has experienced a tremendous amount of urban growth in the last 30 years, but even as people have flooded into its cities, many of the newly built residential areas remain vacant.

So-called ghost cities have become infamous, places where blocks of apartments sit vacant because there is no demand for the housing they offer. But it is difficult to accurately determine which areas constitute ghost cities.

Many tourist areas, for example, become largely empty during the off season, but this does not make them ghost cities. Researchers at Chinese search engine Baidu have harnessed the data they collect on their more than 700 million users (more than half the Chinese population) to perform a scientific study of ghost cities.

The researchers monitored the movements of Baidu users over six months between 2014 and 2015 and used a clustering algorithm to calculate their home location. They then compared the results to a dataset of known residential areas to calculate the urban density of those areas, counting any area with a density of 5,000 people per square kilometer or less as a ghost city. The team was able to identify 50 such areas in China, and also provide data about how they relate to the local geography and larger urban settings.

From Technology Review
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Abstracts Copyright © 2015 Information Inc., Bethesda, Maryland, USA


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