ETAG 27 – Hinged Post Systems

Hinged rockfall catchment fences have an independent base plate and post linked together using a pin. The angle between the post and base plate is variable and is controlled by retaining ropes attached to the head of the post and anchored on the upslope side of the system.

These systems are light weight and highly adaptable to difficult terrain, often being installed with helicopters. The use of retaining ropes means lower forces are experienced at the base plate and the hinged connection eliminates an overturning. Thus, base support is often minimal, normally using two rock or soil anchors and sometimes a small leveling pad.

Hinged post systems have a larger construction footprint as the anchors are typically drilled up to 7 meters behind the fence line (depending on the height of the system). Since these systems use a retaining rope, they are more difficult to maintain after rock fall events. The retaining ropes can also be susceptible to tree fall.

The ETAG 27 tested systems have gone through the approval process according to the “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 click here.