Saving our enironment and more

The big problem would be clearance for large vehicles with oversized loads. One of the obstacles to moving houses is the need to disconnect and reconnect overhead power lines. Think how much worse it would be if miles of solar power canopy had to be moved out of the way. If the canopy sections can be tilted to vertical off to one side of the road when an oversized load is detected, that problem is solved. That would also be a quick and safe way to dump an accumulation of snow. The mechanism could also be used for sun tracking.

Aesthetics (blocking the view of natural scenery) and competition with trees for sunlight are issues that will preclude use on some roads. Another is jurisdiction. Would the government agency controlling the road permit its right-of-way to be occupied by a non-government power producing corporation?

This is not a bad idea at all, but it will take some careful planning and design to make it happen.

Well, posting that tread, I did not think that everyone will say "Hey, let us start building tunnels above our roads tomorrow!" I know, that there may be so many problems which I do not see, and those that you emphasized are some of them (not all). But that is why we are talking here. Who knows, maybe someone will come up with a better solution? This idea came to me when I was working one sunny day on IBM building in Boulder, Colorado. That building has black and white parts of roof. I could not stay long time on the black part of the roof even wearing my working boots and easily could stay bear-foot on the white part of it. While talking about global worming, scientists take into consideration the surface of the Earth. The man made surface may be not as big as China, but as I said, only in the USA it is as big as Austria; add parking lots, black roofs... We cannot disregard such an area which is much hotter now than it used to be before people made it. I am not blaming on anyone - people did the best they could, but I want to reveal that not only those gasses are causing problem, but also man made surface. This is true that making solar tunnels above the road is not easy, but we can stop using dark material to cover our roofs, plant trees next to the roads, which will make shadow...

Writing about covering our ways with solar panels I did not mean regular solar panels, turning toward the sun. I believe that the top surface of the tunnel should be smooth and solid so that it could be cleaned (maybe automatically) and snow could be removed easily. The surface also must be "sucking in" the light (not reflecting it). Whatever is rotating will stay inside the tunnel polarizing and focusing the sun light onto photo voltaic. Railways can be covered with such a tunnel as well.

Thank you for your comments! Andrey.

There is not enough water in the world to keep all of those solar panels clean...

Do a web search for "lotus surface nanotechnology". The first person who figures out an economical means to copy this small aspect of God's design work onto windows and solar panels while retaining good optical transmissivity deserves to make a fortune.