David Fickling & Elaine He, Columnists

The Future of Transport Is the Future of Cities

Migration from rural to urban areas is causing catastrophic pollution levels. That points to a bigger role for train networks.

Dawn of a new railway age? A polluted Shanghai.

Photographer: Johannes Eisele/AFP/Getty Images

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The biggest problem facing the world’s transport planners and visionaries isn’t how to develop the most amazing new transport technologies — it’s how to fit our planet’s fast-growing population into the tight confines of its ever-growing megacities.

The world’s 25 largest cities will add about 113 million people in the 15 years through 2030, according to the United Nations Population Division. About three-quarters of that growth will come in 10 emerging-world centers: Delhi, Dhaka, Kinshasa, Shanghai, Lagos, Cairo, Chongqing, Karachi, Beijing and Mumbai. The least densely populated of that group already has more people per square kilometer than Paris, London, Tokyo or New York: