Thank you, that was my point as soon as I heard about "our" roads being made into non efficient solar panels.
However, given the few experiments conducted so far, it seems that it wouldn't be any more efficient than solar panels, moreover, the technology to cover roads with piezoelectric sections hasn't been tested out of research, AFAIK.
Roads don't need to be covered with piezo surfaces. The piezo could be underneath the surface, relying on compression transmitted through from the surface. It should work with existing concrete and asphalt surfaces.
However, given the few experiments conducted so far, it seems that it wouldn't be any more efficient than solar panels, moreover, the technology to cover roads with piezoelectric sections hasn't been tested out of research, AFAIK.
Here is a short "descriptive" made about 2 years ago : http://large.stanford.edu/courses/2012/ph240/garland1/