First of all, they're already dead so falling off a bridge wouldn't kill them again. And if their legs weren't broken, they would just get up and keep on truckin'.
And just how exactly would that perpetuate the continuation of this series, assuming of course that your idea had even an iota of being successful?
Zombies are killed on every show, they just have to kill the brain. If you drop them from a high enough height, it will kill their brains. Even stomping them in the head with your shoes works on the show. They aren't that sturdy anymore.
For instance, there is a seven story parking garage at 165 Courtland Street Northeast, Atlanta. It would be easy for zombies to walk up to the top. Lure them up there with music or lights, and hang some bait over the side of the building. If they fall seven stories, they probably won't survive.
And just how exactly would that perpetuate the continuation of this series, assuming of course that your idea had even an iota of being successful?
Well, there is the difference between me and a tv character. I would try to solve the problem, and a tv actor is just trying to milk the apocalypse for a paycheck