Here are a few pics of a dirt road I made on a diorama recently. It's in HO scale, and I figured the width by using a HO scale vehicle to judge the wheel ruts with. Basically, the sub surface is blue foam, and I did a little landscaping with light weight spackle. You know that stuff that doesn't weigh anything, but it sticks to foam well and once it's dry you can sand it and shape it just like it were part of the foam. So I kind of exaggerated the shape of the road, high in the middle and edges, by dragging my finger down the tire tracks. Then once it was dry, I used sand paper to lower it a bit, get it shaped like I wanted. Once that was done I painted the base with latex house paint, light brown. I spread plain white glue on the base and glued a layer of sifted dirt from the yard, just plain dirt. Then I used some sand found on the bank of a nearby pond, not too far from the house. I used a sifter and sprinkled it over the base until I had the look I wanted and then soaked it with Scenic Cement, a matt medium from Woodland Scenics. Once it was dry, I used some sand paper to flatten the tire tracks, just 220 grit paper rolled around a stick, and rubbed it in the tire tracks. Then I added the grass, just dabbed a bit of white glue on the center of the road and sprinkled some fine turf on the glue spots, vacuumed up the remainder. And then went back with some Suflor grass tuffs here and there. I swear it looks like a dirt road I've been down before!  

I got the method from reading the desert section of "Essential Model Railroad Scenery Techniques" written by Pelle Soeborg. that guy is awesome! I pretty much used all the same materials he used, except I used my own dirt and sand. And of course I exaggerated the landscape with the light weight spackle, and brought it back down to size with sandpaper. I'm very happy with the way it turned out.

http://s145079212.onlinehome.us/rr/howto/roads/index.shtml

Go to the-railroad-index.com and search for "dirt roads". A quick list showed an RMC entry and an MR online entry

Rod Goodwin
IndexGuy

Nice dirt roads

Can be dirt only ,mix etc. Color depends on part of country bing modeled
No glue required :)

http://www.flickr.com/photos/wsdimenna/6501923095/sizes/z/

This was a demo done during course of show.

Bill d

An experiment and my first attempt at making a dirt road by sanding and scraping extruded foam.

I'm not finished yet and will next experiment with paint, sifted dirt or a combination of the latter with extruded foam.

I have used a similar technique in the past with good results.  I find using sand is ineffective because the particles are much too coarse in scale.  You need to remember that a quarter inch piece of gravel in HO scales down to the finest powder.  What you want is a slightly rough surface of the right color with the look of smoother areas in the wheel tracks.  Sanding dense foam gives a good texture for that, while also giving you good control of the process.

Based on my using it for dirty yard ballast and scenery ground texture, I believe sanded grout would make an excellent dirt road.  It comes in a myriad of colors.

http://www.homedepot.com/hdus/en_US/DTCCOM/HomePage/Brand_Pages/Custom_B...

Peter

I suggest looking for photos of dirt roads in the area you are modeling as the type of dirt , type of plants, and type of road varies greatly depending on location and use. I'm a surveyor and have driven on thousands of them(and luckily never gotten stuck) ...DaveB

I've posted this photo before somewhere...

I used very fine sand and represented compacted areas with dry-brushed acrylic craft paint.  If you can't get sand fine enough, sanded grout (maybe a mix of colors) would probably also work for a base, and you could dry-brush onto that.

and it's similar to a scene I started working on this last weekend.  What I've been doing is laying down some diluted white glue and sprinkling on WS fine white-ish ballast, then while things are still wet sprinkling on some real dirt, concentrating on the 'road' area where the tires would go and on any low spots to represent the natural ruts and mud puddles one can get in such lots.  It does the trick, but I like the look of yours better.  Maybe if I put a wash of umber or something, and a dry-brush of a lighter color on mine in the tracks it can come closer to what I want.

Oh and the point: it all depends on how the dirt roads look in the area you are tying to replicate.