The wife and I with friends were in Australia and New Zealand this past March. While there I took a couple of pictures of the Sydney bridge walkers. Quite a view from the top of the bridge.
It is a tourist type thing Jim. They have tours that go up the bridge about every 15 minutes. It takes about two hours to walk up to the top and back. Cost is about a couple hundred dollars for two if I remember right. The bridge is NOT open to the public other than through the tours. Security is pretty strict also. We had a lot of fun doing it.