China's cities need to grow in a more compact way.

S ince the 1990s, China has undergone astonishing economic growth, and its extensive urbanization has become one of the most striking development signatures anywhere in the world. With the world's largest urban population, China's urbanization experience provides meaningful insights on future urban development in other countries. 1 Because China has an extremely low per-capita land area, constructing compact urban forms is regarded as one of the most important considerations for China's sustainable city development. 2 This is because, in general, a compact city can help better utilize public transport services, strengthen urban community multifunctionality, increase the quality of city life, reduce energy consumption, and improve the urban environment. 3 The question is, however, are China's cities developing toward a more compact form? We assessed the compactness of 35 major cities in China in 2000 and 2007 by using a normalized compactness index (NCI) (0 < NCI < 1), which is defined as a ratio of Thinh et al.'s compactness (T) for a given city over the maximum compactness (T max) for a hypothetical round-shape city. 4 NCI is independent of the dimension of a target city, and the greater its value, the more compact a city. The 35 major cities in this paper include 26 provincial or autonomous-region capital cities, four municipalities , and five cities specifically designated in the state plan (or state-plan cities) (Figure 1), the same cities as studied by (Jinan) (Figure 1). The mean of NCI values for the 35 cities was 0.131 (0.060 (standard deviation). The skewed distribution of NCI values in 2000 showed that the majority of cities in China were relatively noncompact. Among the 12 cities with the lowest NCI values, 8 were low-population cities. Beijing's NCI value was 0.112 and Shanghai's was 0.130, and their NCI values ranked 26th and 18th, respectively. In 2007, NCI values ranged from 0.052 (Nanjing) to 0.335 (Shijiazhuang) (Figure 1). The mean of NCI values for the 35 cities was 0.145 (0.066 (standard deviation). The skewed distribution of NCI values in 2007 showed that the majority of China's cities were still relatively noncompact. Low-and high-population cities were almost evenly distributed within each NCI class, with the exception of the largest NCI class. Beijing's NCI value increased to 0.131 whereas Shanghai's remained unchanged, and their NCI values ranked 20th and 21st, respectively. Between 2000 and 2007, the change in NCI values varied tremendously among the 35 cities (Figure …