Okay, I play with diecast cars too. I love the front grill on the vehicle and thought maybe it was a scratchbuilt. Bloody beautiful work though. Now on to roads. Here is the tutorial.
First, given this a read. It it where I got my idea from.
http://www.architectsofwar.com/Howto/roads.pdfNow shingles can come in two types. Starter and regular. Regular have one large piece and several small pieces. Good, but the small pieces are not as useful. Starter shingles have two large pieces, which are great for 28mm roads as they come in 7 inch widths, or the approximate correct width for two 3 inch lanes. Perfect for our chosen scale.
Now shingle has two sides, rough and not so rough. We use the not so rough so for our roads as it looks less like gravel than the rough side. To help control the aggregate on the rough side, I cover the rough side with electric or duct table. This also helps keep pieces together once you start adding cuts and cracks to the road and allows you to cut holes in the shingle to add craters.
You will notice the not so rough side has a strip of plastic wrap running over it. This is a bit of a pain to remove by hand. Instead get a wire brush and just go to down on the plastic. This not only gets rid of it, but also helps texture the smooth side under the wrap.
Next to help smooth out the transition between this smooth area and the rest of the not so rough side I spray textured spray paint light around. Not a ton, just a medium to light spray. Note this will not cover up the smooth area entirely, but when you look at road surfaces, repairs are a bit of hodge podge and this helps simulate that.
Now we start to post-apocalypse-ify it. I cut lightning style cracks in various places. I use to use a screw driver and cut these pretty deep, but this was murder on my hands. Instead I now use a awl and just carve them in. Much simpler. I tend to run these cracks from one end to the other and just go randomly. I don't really plan this out and just let let is happen organically. Generally cracks will start at holes or edges.
Now for paint. I buy this.
http://woodlandscenics.woodlandscenics.com/show/item/ST1453/page/1But that won't go very far. Instead take that and get is color matched at your local DIY store in latex paint and use that. Much cheaper. You can also mix black and grey, but I have yet to make a color that is better than this. Put this down in a even layer and let it dry.
Next we have to add washes to the cracks and holes so they don't disappear as the latex paint with slightly fill them in. I use GW black washes for that, but any strong wash will work.
Now to bring out the texture we drybrush white or khaki across the whole surface. Do this LIGHTLY! I cannot over emphasize that part. Too much and it looks bad.
Now let everything dry.
Once everything is dry is time to pull it all together. Mix a wash of black (30%) and brown (70%) and then spread this over everything. This should be really thin and should not obliterate your drybrushing. It will just lessen the contrast some. Let this dry.
Now you could stop there, but that is no fun. For fun I take out random colored washes and drip them in strategic places. Like green and different browns. I will take my finger and spread them around, wash small areas with a brush, or even drop it directly from the bottle. For this we are going for random color variations.
I also take black weather powder and run streaks down parts of the road where tires and exhaust would leave marks. This is easy to overdue, so just do it in a few places.
Finally, I will cut of small squares of paper, small pieces of balsa wood, and paper flyers and glue them around to represent the debris that results from lack of maintenance and cleaning. I will put these all on clean and then wash them with black or brown washes.
And that's it. Literally, if a monkey like me can do it, anyone can. Let me know if you have questions.
All the best.