Hidden in cities, vast swathes of land are waiting to be reclaimed. It is the space devoted to parking cars, which sit idle for 95 per cent of the day.

In Singapore, 5.6 million people can count on 1.3 million parking spaces - more than twice the number of cars. In the United States, parking spaces amount to an area as vast as its state of Connecticut or the Malaysian state of Terengganu, at just over 13,000 sq km.