I am going to show a bridge from the How to Make Wargames Terrain book.
The popsicle sticks are cut, aligned and then glued. We want the bridge to look more Imperial than the example though.
Final cuts and then paint them lightly with your favorite brown. Remember, you can make more cuts to show the effects of the ravages of total war or even collapse the middle of the bridge.
Super glue on the support legs and paint on details like mud. I stamped on the aquilla symbols. You can also use a lighter and create burn marks effectively to give the impression that a flamer was used previously.
Last, remember to have fun making terrain pieces and if you don't like the results at first, try it again later or experiment on it with more damage so none of your efforts are wasted.