Loads borne by a tie-in point during ascents and descents on a basal-anchored stationary rope system

Abstract

Previous studies that quantified or simulated loads on a tie-in point (TIP) during climber ascents, abrupt stops during descents, and falls considered crown-anchored stationary rope systems (SRS). But climbers also use basal-anchored SRS when working in trees, and because both parts of the rope—lead and fall—carry a load, the TIP presumably bears a greater load than on a crown-anchored SRS. In this study, tension in the fall and lead of a rope used in a basal-anchored SRS was measured during climber ascents and abrupt stops during descents. As expected, loads borne by the TIP were greater than on a crown-anchored SRS. Loads also varied among three species selected for varying degrees of bark roughness; greater loads were borne on the TIPs of a smooth-barked species. It was also noteworthy that pre-loading a TIP to determine its safety, which climbers do before ascending, increased the total load during ascents, presumably because tension set during the pre-load was not released in the fall of the rope prior to the ascent. To reduce the likelihood of TIP failure, climbers are advised to take care when selecting a TIP that will support a basal-anchored SRS.