We encountered a lot of swing bridges on our trip. A lot of them swayed side to side as well as up and down when we crossed them, requiring more concentration than you'd expect. A lot of tracks in NZ don't have bridges or have a wire to walk on with two wires as hand guides. There are deaths every year there in the backcountry from people trying to ford streams and rivers. Yikes. Luckily, we were always able to use a bridge.