The world's big cities are choking with pollution and endless traffic jams, writes Colin Todhunter – except one. Copenhagen, faced with these problems half a century ago, decided to act. Now it is showing the world that cycling is not just the basis of a sustainable transport strategy, but is key to making our cities clean, green, human and livable. May the global revolution unfold …

India's cities are in crisis. They are clogged with traffic, choked with pollution, blighted by concrete flyovers, overcrowded, suffer from power and water shortages, are prone to flooding and can at times be almost unbearable to live in.

The plan to introduce 'smart cities' to India is intended to remedy many of these problems.