Another vote for wet/dry sandpaper. However, in the early days, you also had cement roads and lots of gravel/dirt roads.
For cement, I use plaster or spackling compound and frame it up with popcicle sticks. Then paint with armor sand or similar, and then, with an old toothbrush, lightly splatter some light gray over it to represent ricks in the cast cement.
For dirt roads get a few cheap matchbox trucks and put down some plaster of paris, and when it starts hardening up run the truck wheels over it. after it drys, paint it with water colors and carefully put some epoxy or, if you have it, some future floor wax into some of the ruts to simulate water.