Taking inspiration* from Stu's post here about making ruined roads, I bought two vinyl flooring tiles and set to work on making my own set. I don't think they could have turned out any better!
*translation: blatantly stealing ideas
This is just a representative sample - I have 6' of roads in total.
They take a bit of work with scissors, an X-acto knife, and a fine-scale gouge, but the end result is great. I made a stamp with some foam glued to a piece of wood to do the lines, and that resulted in a really patchy look, which worked perfectly.