I found the image immediately recognizable. Regarding the snapped twigs: I see this working on two levels. Purely on the surface it fits the activity of the scene and the environment in which it takes place. (At least in my minds eye and ear and yes I placed it in a wooded area) As a reader I placed myself on the other side of the divide. I would image twigs snapping in advance of and in conjunction with the coming rope bridge's construction. They would no doubt be muffled, or lost to me completely. They are the sounds of work preceding work.
They are the early sounds of the effort, faint or lost to the opposite side of the gulf or canyon--real or figurative to be crossed and just the hearing of them, or almost hearing them, would be a bridge in itself--Reached by the sound maybe and the promise of more substantial contact.
I have no idea if this is what you were going for T, but my head went there right away.