These are a few Timecast resin bridges I bought some years ago when Triples was still running. They are very nice castings with well defined stonework and some roughness to the road surface, both of which take a drybrush well.
The first few I bought were these large ones, the roadway is wide enough to accommodate 30mm wide bases. For many of the smaller games we play, these turned out to be a bit big for the rest of the terrain pieces.
I then got a batch of these smaller ones, the lengths are still plenty long enough to go over my various river sections comfortably, but they are considerably narrower and juts look better with a lot of my buildings and trees. The water parts are painted blue because everyone knows water is blue.
Stone bridges are all very well, but sometimes you needs something more modern. I still have my old Airfix Bailey Bridge, and a couple of scratch built girder bridges, but I was very taken with these Leven Miniatures 6mm bridges at Joy of Six recently. They have quite a range of various historic bridges, including Nimy bridge.
I got one of these curved girder bridges. They are a bit cruder then the Timecast ones, but paint up fine. I basecoated this one black then finished in a mid grey with a light drybrush. The black cut-ins aren't too obtrusive on the finished thing.
This one is a section of 6mm Bailey Bridge. On reflection I should have bought two. I finished this one in mid green with a bit of a drybrush.
Here they are with a couple of bases of figures, you can see how the 30mm base fits in the bigger bridge model, but for the sort of grand tactical and operational games I tend to end up playing, the smaller bridges just work better I feel, particularly on Hexon terrain.