Don't think so, in fact. I know sometimes with lemur walkthroughs they have bridges that they electrify completely when new animals are introduced for a few days so they learn to avoid it - this might be the case, but I suspect not. I think the not-actually-that-high sheer drop is the only thing stopping the baboons accessing this bridge.
Thanks, the drop might put them off but if there were fights or something I don't think it would stop them!
Also that water does not look that deep, surely they could paddle along to the bridge ? Or maybe even along the brickwork. A determined primate can do surprising things. Even deep water moats have been crossed by Macaques swimming through it, and I`m talking six to eight foot deep. Apart from all that its damn hideous!!