To make my roads I use a relatively smooth material such as Masonite. I paint it either concrete or asphalt color.  It is is concerete, I score expansion joints.  Then I paint the lines.

I normally use thin plastic sheets. My cheap source is plastic signs, (For Sale, etc. ) found at Home Depot, and Lowes.  I cut the road to shape and using the back side, prime it and paint the color of your choice. If it represents concrete I scribe the expansion joints. Tar filled cracks are done with a fine tip Sharpie.