When an author writes a story it is a given that the characters are going to face challenges. That is the point of most novels after all, the adventure. Adventure is just another word of trouble as Louis L'amour described so well. Of course a story can have too much adventure. The plot can get bogged down in side quests that have nothing to do with the main body of the work. But for the most part if the intrepid hero(s) are trekking across a trackless waste something should confront them. Bridges are excellent for this. For one thing the very existence of the bridge means that there is something potentially dangerous to cross. If the hero comes across a flat plane and suddenly there is a bridge like structure flush with the ground in the path the obvious conclusion is that there is some hidden mire waiting to trap him there. A bridge is built, often at great expense and effort, to overcome a difficulty so if there is a bridge there logically follows a difficulty. Then there is the dynamic that someone had to build the bridge. By the very nature of the requirements the better the bridge the more powerful the builders and they are probably in the vicinity. Folks don't put that much effort into a structure unless they intend to use it. A simple rope bridge offers an immediate danger but probably not a massive danger from the builders. A three tiered megaspan crafted out of some space age polymer makes for an easy crossing but its creators are probably going to be a force to be reckoned with.
There are of course natural bridges that offer their own challenges. A stone bridge might offer no particular challenge to the part but it can set the atmosphere of powerful natural forces at work. A snow bridge is more common and more suspenseful. A tree bridge also sets the scene for the reader. A tree large enough to be an effective bridge means an old, deep forest.
Bridges are a real workhorse of entertainment. So go out there and burn that bridge when you get to it and find some #mondaymotivation!