Raised Draperies: Defining Hybrid Barriers and Attenuators by Application

Beginning in the 1980s, research and development of flexible rockfall fence systems resulted in a wide variety of systems developed to protect facilities from falling rocks. These systems were basically a fence with a wire mesh supported by an infrastructure of cables and posts that were specifically designed to be flexible. Specialty manufacturers offered up a suite of designs and systems for a broad range of rock impact energies and rockfall bounce heights. Soon practitioners were applying these systems to a wide variety of terrain that included the standard fence at the base of the slope, placing modified versions of flexible rockfall barriers and unsecured draperies in incised drainages, draping long steep slopes, and placing barriers and drapery over rock slopes in narrow corridors with limited catchment. The systems designed for these slope conditions were being developed not to stop the falling rock but to attenuate the rocks energy and control the rocks trajectory so that it would be deposited at a safe location. Soon the industry ended up with two common names for these systems: Hybrids and Attenuators. Most practitioners acknowledge these two titles, but the definition of which term applies to which system often gets blurry between agencies, manufacturers, academics, and consultants. There is an important distinction. While the two systems are very similar construction, as both systems provide a standard unsecured drapery with the added benefit of elevating the upslope end of the drapery off the ground surface to catch rocks rolling down slope above. In one design, rockfall is channeled directly into a suitable containment area at the bottom of the installation, and in the other design the rockfall exits the bottom of the mesh to continue down the slope into a series of similar systems that dampen motion and control the rocks trajectory that is eventually guided into the containment area at the base of the slope. To obtain some standardization in product development, proper usage, and testing methods terms that allow distinction between these different types of systems needs to be formalized throughout the industry. This paper reviews the history and defines the terms for attenuator and hybrid systems, current design methodology, results from full scale tests and discusses nomenclature and performance characteristics that can guide the development of industry standards.


  • English

Media Info

  • Media Type: Digital/other
  • Features: Figures; Photos; References;
  • Pagination: 17p
  • Monograph Title: Proceedings of the 72nd Highway Geology Symposium (HGS 2023)

Subject/Index Terms

Filing Info

  • Accession Number: 01892727
  • Record Type: Publication
  • Files: TRIS
  • Created Date: Sep 11 2023 11:42AM