This makes for fascinating reading, including some revealing calculations on the calorific energy consumption of alternative modes of transport. I've long wished that I lived in a city where electric scooters or cycles made more sense as a primary means of moving around.

But a strange thing has happened. The obstacles we identified in Delhi seem less daunting today than a year ago. Something big is afoot. E-bikes in China are outselling cars four to one. Their sudden popularity has confounded planners who thought China was set to become the next automobile powerhouse. In Europe, too, e-bike sales are escalating. Sales have been growing by 50% a year since 2008 with forecasts of at least three million sales in 2015.

I have the strong impression that a cloud of discrete but related developments is converging. In the background, a combination of energy costs and economic insecurity adds urgency to the need for change. At street level, myriad innovations in hardware, systems, and business models are giving us the component parts of the ecosystem we yearned for in Delhi. A profound transformation to the mobility profile of modern cities no longer feels like a dream.