That's a model actually. The way you can tell, is that if you shoot at it, it won't leave any bullet marks.
You could easily brush this, or just use the model in your map, and add a CLIP brush over the walking space, so players don't fall through--models don't block the player.
If you want to brush it, I would recommend first building the bridge complete, with no rotated/broken slats. After that's done, Use clip tool to cut some of the boards in half, and then rotate/Vertex manipulation some of the pieces to make them look like the picture.
If your going to build it by hand, try building the regular bridge, befor asking more questions on how to do the more fancy stuff
edit: lol we all posted at the same time