A solar roadway is a "smart road" which combines energy generation and driving surface. This is an idea us science fiction enthusiasts have been burbling about for years. Not only could enhanced road surfaces provide electricity for electric vehicles, but they could also have LEDs embedded into them for transmitting messages such as road conditions.
It sounds like a Utopian fantasy from the 1950s, but the US Department of Transportation granted $100,000 for a solar roadways prototype in 2009. Then the Federal Highway Commission granted a follow-up $750,000 for continued development of the project in 2011.
In addition, (now this is purely my own speculation), if the road can transmit a data signal, then why couldn't it also direct a vehicle? Imagine being able to hop into your car and say "take me to the Post Office" and the GPS works together with the road to drive you there automatically, removing the need for a human pilot at all. No more accidents from sleepy or intoxicated drivers! Road accidents kill over 40 thousand Americans per year. It would be a giant leap from solar roadways as we are presently seeing launched to autopilot roadways, but it would be a leap worth taking.