I really do not beleive you know what slate edits are. Slate edits are the basic ivisible slate interior with an altered watertexture placed underneath for the illusion of ground. The reason for this is that it is much less laggy, much less glitchy, and requires much less loading than a flat terrain. Water textures could be used to make the roads like you want them, but the fact that doing such a thing would be so impractical, anyone who is actually capable of doing it correctly will most likely elect not to.