Bit hard to guess on the picture, but is it tall enough for them to use without knocking their heads on the roof?
Generally if the animals can use it, so can the zookeepers. You can check travesty for animals in the heat map.
Of course it's in a Enclosure. It connects the Gate with the Orangutan Island. I know that they should be able to use it because I did it already in the past and I know from my Flamingo-Pond that Zookeepers can even walk on a Treetrunk that isn't as wide as the Bridge. Maybe the Hitbox is really way too high
Ok, just found out that the Logs on Top of the Bridge are a bit lower than a Doorframe
I should've checked this first even though it looked high enough to me. I wish I would find another Solution. I really like the Bridge Design