The idea is simple, a player can have a few different options of color choices to place down a colored sheet of road that will be dynamically darkened based on the paths use. These would initially have to be made of lighter colors that is not too dark and the road usage would have to sort of fade in and out as you use the roads. The higher the usage the longer it takes to fade back to the original base color.
Rather than manually building road designs like this: Roads with Depth [Road Templates]
Here is an example of roads being generated based on paths:
This way it will be really cool to watch your highly used roads change over time as you adjust your town. While seeing how useful a road is can be nice feedback to the player that they were justified in placing this section of road but not this other section as its hardly ever used.