Has anyone ever seen that National Geographic program on the autobahn? It's probably the world' most sophisticated road network. I can't remember ALL the facts and figures about it but the roads are apparently never built with more than a 4% gradient.
Germany spends twice as much money per km of road than the US does. The roads are built at a slight angle left or right so that standing water is drained to the side where it is then collected, contained and treated before being released into the waterways.
It's camera/computer control system can predict likely congestion areas and adjust the speed limits automatically to govern traffic.
I did burn it onto DVD - very interesting indeed. Features some crazy guy who designed and built his own 400km/h speedster!