Every year, cars become more sophisticated. They can adapt to the speed of traffic, generate power from braking, and even park themselves. But the roads are pretty much made of the same stuff that was under your grandparents' wheels, even though today we drive an average of 13,000 miles a year. Not since the 1800s, when we started replacing dirt and rocks with asphalt, has the driving surface seen a major change. But now, inventors, designers, and engineers are trying to make roads more useful, more visible, and less expensive.