I've no way of showing a picture, but I think I can just mention that it is easy to build a girder-type bridge using yardsticks. Yardsticks used to be free, but these days I have to buy them. Anyway, imagine laying two yardsticks side by side and then laying a third centered over the other two. Then imagine two more, one on each side, making the vertical portion. I built one using this idea, with braces -- or whatever -- placed at intervals along the outside using match sticks. I painted mine dark green because I had a can of spray paint. It looks pretty good. Not exactly prototype, but since I've discovered I'm a better blacksmith than an ho modeller, I'm happy. I was careful not to have joints overlap, and I placed the sides so that the bending of the horizontal part under load would be in shear rather than tension. I use old sewing needles (they break easily, and make great nails) pierced thru the sides into flat part. Of course the yardsticks making the bridge were glued together - white glue.