@trh
One way to answer "Why?" is to come at the subject from as many angles & altitudes as possible:
Purpose: is the road designed to be fun? Safe? Fast? Economical? Does it go down, up, or both?
User: what do they need? What do they have to work with: a car, truck, trailer, bicycle, wheelchair, stroller?
Environment: what's the soil like? Will it rain or snow often?
Perspective: as it is, this looks pretty simple, but I imagine if you view it from the opposite angle, the terrain is more clear.
"What do they believe that makes this a good idea?" is usually more helpful than simply, "Why would they do that?"