The strategies I've listed should, for the most part, prevent getting overwhelmed. However, there are times when it can't be helped. Make sure you do have Stami-up for this, or just really good timing: keep leading zombies against one side of a walkway (or something similar, in general, usually on the side you're already on), then run back around them on the opposite side (so if you're on the right, run past them on the left) just as they're about to hit you. Use your right stick (or mouse) to navigate, do not strafe. There's roughly a 1/2 second delay before zombies hit you when they have to turn around to face you. If the opposite side is a little blocked, shoot the outermost zombies prior to running.