I set out curves to match the layout of this map. Whenever I apply array and curve modifiers to the mesh I am trying to duplicate along the curve: the mesh gets blown up in it's dimensions. Other than that, there is nothing wrong with it, just the fact the dimensions get way too big. I am using bezier curves, i have applied rotations, scale and location to all the curves and the mesh I am trying to duplicate along the curves.
I've noticed that when I apply scale to a curve that is used as a curve modifier by an object, this object always get bigger/smaller, so I guess the solution is either not to apply scale to the curve you use (or to only work its shape in edit mode which is even preferable as you will always stay at its original scale), or to scale it again and apply scale until the object is at its correct size, but this is not the good solution.