Roads sometimes have specific toolsets for them in the game editor. Unreal uses Landscape Splines for this. https://docs.unrealengine.com/latest/INT/Engine/Landscape/Editing/Splines/index.html Do you have any image references for the kind of road you want to build?
Let me rephrase what i asked because i wasn't really clear. You know how unreal engine 4 they have the terrain editor and you can pretty much paint all the awesome terrain you want and even scupt it. For something more like this :…