My understanding is one of the challenges with covering roadways with solar is that you also need the infrastructure to get the energy to where it needs to go. There may not be a sufficient connection to the grid to make use of that power.

But along electric train lines, you have lots of power feeding in so you have ways to get power out. This appears to be a pretty brilliant option:
independent.co.uk/news/uk/home…

#solarenergy #trains #turbines