When the historian and critic Lewis Mumford said that adding car lanes to deal with traffic congestion was like loosening your belt to cure obesity, his sardonic advice was rarely heeded. Traffic remains one of those facts of life: dirty, congested, rage-inducing, inevitable.

But picture for a moment the last time you were stuck in traffic – gritting your teeth, trapped in your car – and imagine instead you were sailing above it, getting from A to B in half the time of that miserable drive.