Planning today for tomorrow's cities

The movement of Chinese citizens from farms to cities over the past 30 years is the largest and fastest urbanization in the history of the world, by far. Getting this process right - planning cities over the next three decades that are productive, livable and environmentally friendly - is crucial.

Economists have found that people living in cities are generally more productive. The close interactions made possible by easy access to individuals, groups and ideas multiply the opportunities open to inventors, investors and entrepreneurs. These so-called agglomeration effects are a key part of continued economic growth.

Robert Guild, director of transport and communications for East Asia at the Asian Development Bank, said the ADB calculates large positive returns for infrastructure investments in China. "Agglomeration reduces the costs of interaction. It lowers costs throughout the supply chain. Plus, it allows people to generate ideas as they serendipitously come into contact with others."