There is growing interest in planning sustainable cities, and for good reason. The depletion of fossil fuels, escalating pollution, carbon emissions and the resulting threat to the climate are strong incentives for trying to increase sustainability in cities around the world. The concept of sustainability as it applies to cities is broad, with the energy consumption and emissions of buildings being only one concern. Other key sectors are industrial production, energy supply, and water, waste and transport management. Transport is a particularly important item on the green accounting sheet because it is responsible for massive energy consumption and the resulting heavy pollution and carbon emissions. In the USA transport accounts for no less than 28% of carbon emissions.29 Giving higher priority to pedestrian and bicycle traffic would change the profile of the transport sector and be a significant element in overall sustainable policies.