Potholes are a national obsession. But there's much more to them than you might think. Ruth Alexander digs deep into their costs for business and society - where fixing two holes in a motorway can cost half a million pounds. But she also finds all kinds of entrepreneurial imagination going into solving the problem. Everything from new data analysis to 3D printing drones may be the answer. Beneath it all lies a fundamental question. Can we learn to value roads, and maintain them as a vital national asset, smoothing the way to big business and social gains?