Shane wanted to get a look from the walkway so left me driving. There is no wall to scrape against and no steering to do, so now that I knew I wasn't being affected by any vertigo, I was okay about it. Further along there was an unhappy girl who was clearly frightened of the crossing. She didn't want to be by the rail, possibly as she didn't want to look but she wasn't enjoying being so near the water. Her mother tried to encourage her to wave to the boat but she was too preoccupied for that. I understood. The combination of the height, the narrowness and crowds gave plenty of reasons for rising anxiety. After we passed I could hear her sounding more and more panicked. She was too big to be carried. As we got to the end I could see an official walking along and making sure no-one else stepped on the aqueduct clearing the walkway and addressing people waiting to step on he asked that they step back as a distressed child was coming and needed to pass. Her dad had turned back and was leading her off, sobbing. It's not for everyone, but we enjoyed it.