Faced with ageing and insufficient transport infrastructure, growing inequities particularly on the urban fringe, increasing air pollution, and increasing rates of road injury and non-communicable disease, twenty-first century cities need to urgently implement strategies that lead to sustainable agglomerations if globally, we are going to limit global warming to within 1.5 °C. On a pathway to limiting global warming, we need to focus attention on the road transport system which contributes more than 20% of greenhouse gas emissions (GHG); sustainable urban transport systems must, therefore, be an urgent priority for policymakers across the globe.