I'm really liking the carved effect I've got now, but I'll give the dots and dashes a try. If it works out well, I could easily offer both versions of the roads, so people have a choice of which one they prefer.
Also, I was thinking...after drawing the dots/dashes, I could duplicate the layer and gaussian blur the one underneath for the outer glow. That way they can be manipulated separately.
EDIT: I just gave the dots/dashes a quick try and I'm running into a very strange problem. As I'm drawing the lines, the dots/dashes are visible, but once I start using the Knife tool, to cut away the filler pieces (I'm not sure what the right term is for that), the line turns solid... Any ideas what I'm doing wrong, or how to avoid that? (I'm using Paint Shop Pro 8)