I have used this title to cover the man made communications of roads, bridges and fords. Since no model terrain of any of these existed when I began wargaming, I have made my own.
My early roads were strips of card, but a few years ago I replaced them with a modular road system, which was painted onto cut up vinyl. We had had a set of cloth backed vinyl table mats which my wife was going to throw out, so I recycled them to make my roads. There are long and short straight sections, cross roads, T-junctions, angled junctions and angled cross-roads. The roads are all 30mm wide.
Because they are vinyl, they are flexible and follow the contours of the ground. I painted them on the vinyl side with a light dirt colour, green edges and a darker brown lines to represent ruts made by the wheels of vehicles.
Here are some roads curving over the terrain in a wargame of Albuera.
My original bridges were all made as wooden bridges from model railway planking, with sides from model railway fencing. I have some smaller ones to cross streams, and larger ones to cross small rivers.
More recently I have made a number of stone bridges, all with archways. These are designed to fit into my rivers, so giving a natural look to the bridge, rather than it being raised artificially high.
I made these many years ago. They are simply pieces of clear plastic, with a few gravel chippings on the side of them to delinate the ford. They can be placed at any point in my 3″ wide rivers.