Get some 3mm cork sheet and break off a price to form the rough edge of the asphalt. Use white glue to stick it to the base. Remove excess glue with a spatula.
With AK8013 Asphalt past, cover the cork surface. Use a spatula extend the surface to make it as flat as possible. Moistest the spatula to remove marks. Finish the edges of the cork with paste diluted in water with a brush
AK8021 Terrains Light earth: spread on the earth bit with a hard brush. Blend the edges of the tarmac in with paste diluted in water. Add small stones and grit in a random patter while wet. Fix by patting them in. After letting it partially dry, tap with a sponge to gain roughness.
Add small grit in small amounts on the tarmac. Fix them with water and white glue blended 60:40.
Mask off the road edge marking
Airbrush the shoulder stripe with Titanium White thinned. Dry and remove tape
Add shades and depth with a wash of Industrial Earth thinned south white spirit. Apply to Tarmac. And earth
Add depth to the boundaries terrains stones and potholes with Sepia thinned with white spirit