Single Point Highline Anchors
In many ways creating a single point highline anchor is similar to rigging a longline from a tree anchor or large immovable object. There is of course, a much higher consequence if the anchor were to fail. When planning for such an anchor, you need a very strong sling that has a high load rating and sufficient safety factor, such as a spanset. Also, be certain that the object you’re anchoring to is incredibly solid. The last thing you’d want to have happen is have your anchor shift under load.
In addition to the main anchor, you want make a backup anchor to protect against a main anchor failure. Having a backup anchor demonstrates an aspect of redundancy, a concept that all highline riggers must keep in the forefront of their minds. The backup anchor can be constructed of a second spanset or sufficiently strong rope or webbing. If either of the latter are used it’s best practice to have multiple passes of rope/webbing run around the fixed object. If possible, it’s even better to connect the backup anchor to a completely independent anchor point. When it comes down to it, you want to be certain that any single point highline anchors can easily take the loads you will be generating in the highline. If you are in any doubt about the anchor point or the system itself, consider using a multipoint anchor. And don't forget to tie off the webbing tails.