Fixed post (aka fixed-rotation or rigid) rockfall catchment fences have a robust post with an integrated base plate. The angle between the base plate and the post is fixed and cannot be altered. This is achieved through welding the base plate directly to the post beam with the help of stiffeners. The result is a self-supporting post requiring no retaining ropes for the post head.
The advantage of omitting the retaining ropes is a system that has a smaller footprint. This eliminates the need to install anchors upslope of the system and provides unobstructed access to the system in case of an event.
One compromise is that fixed post systems require more extensive anchoring for the base support. Where bedrock is located at surface, the posts can be anchored directly to the subsurface, but in the case of soils, a system of concrete pedestals with compression and tension anchors is required.
The ETAG 27 tested systems have gone through the approval process according to the European Technical Approval Guideline 27 “Guideline for European Technical Approval of Falling Rock Protection Kits”. This entails 1:1 scale testing of the fences for both Maximum Energy Level as well as Service Energy Level. For more information about the testing guidelines, please