Solar roadways are being touted as an answer to energy shortages - enough energy generated by the roadway itself, and, voila, car culture can continue. But trucks and cars for intercity - and intracity - transport should be regarded as part of the past, not the future. It's 20 times as energetically efficient to move passengers and freight by rail as it is over the road. The limiting factor in road transport is *not* the availability of asphalt, it's the fact that if we still have the car culture 15 years from now, we'll be burning asphalt for motor fuel, even if it's to generate electricity. In fact we're doing that now - that's what the "tar sands" are - asphalt.