In addition to my wargaming, I do a bit of railway modelling (less lately) and have had in the past an O gauge garden train. Seeing some great urban modelling in the hobby magazine made me wonder if I could add some track to one of my wargames tables, more as something to break up the look of items on a cloth, than something to give cover saves. In order to see if I could help create the grungy look of some industrial trackage, I bought a couple lengths of O gauge track, the flex track variety, usually available in 30" or 36" lengths depending on brand and cut them in half. I then took the 4 pieces of track, and mounted them on a thick card base which I had cut to match the track's length. After that I applied PVA glue around the ties/sleepers, both on the ends and between the rails, and sprinkled sand/grit over that. Before the glue dried I wiped the sand off the tops of the rails and ties, and from the ends of the rails. Once the glue was dried (well not actually, hence why it fell to bit and had to be re-glued) I sprayed the section with several spray cans, mostly a dark grey with mistings of light grey and black. Last painting step was some drybrushing, brown on the ballast, and light grey on the ties. To dry out some of the weathering powders I bought I, then used then on the rails to give a rusty look, and were the rust has washed off and stained the ties.
Here's how it looks, ideal to appear in an Imperial city:
If you wanted to go further, try something different, you could use a strip of card under the track and more sand/grit to build a ballast shoulder, like you'd find on mainline tracks. You could also silver the tops of the rails for more frequently used rail - either by paint of by removing spray from the rail tops with an eraser/ Brite Boy. Last of all you could use an airbrush to put a line of black down the centre of the ties to simulate oil staining from locomotives.