Solar Roadway
A solar roadway is a road surface that generates electricity by solar power photovoltaics. A solar roadway would be constructed from a series of structurally engineered solar panels sturdy enough to be driven upon.

Original Image: Giveen via MediaWiki Commons
The concept being investigated in the United States. It is hoped that the energy generated by the roadway would pay for the cost of the panel, thereby creating a road that would pay for itself over time. An additional possibility is the addition of LEDs to serve as smart pavement marking, and lighting up the road for safer night time driving.