Ring Net Drapery for Rockfall Protection: Installation Observations

This Experimental Features study provided an opportunity to compare the installation of different weaves, weights, and fabrication of ring nets for a large slope protection (drapery) installation. To evaluate cost‐ and performance‐competitive materials to cable net drapery, Washington State Department of Transportation (WSDOT) proposed a study of ring nets to the FHWA as an Experimental Feature on a federally‐funded rockfall mitigation project. At the time of the study, only one manufacturer was producing ring nets that could meet Buy‐ America steel requirements. To compare attributes and performance of various ring nets, a Buy‐ America steel waiver was concurrently sought from and granted by the Federal Highway Administration (FHWA) to allow foreign sources of ring nets. The project entailed covering a 300‐ft‐high slope, consisting of large diameter columnar to blocky basalt, with both standard unsecured and post‐supported (hybrid) drapery. Four different ring nets were specified that included bound wire loops and wire rope rings utilizing either 4:1 or 6:1 weaves. Control sections of cable nets were incorporated to compare performance. Results indicate that the ring nets with 4:1 weaves and wire rope rings had the greatest tendency to contract in width when lifted. In comparison, lightweight 6:1‐weave ring nets and cable nets exhibited virtually no contraction. Pre‐attachment of wire mesh to the ring nets that were prone to excessive contraction led to the widespread failure of the fasteners and the detachment of the wire mesh. Panel contraction resulted in greater effort to vertically seam adjacent panels. Material shortages were encountered due to the Contractor’s (Janod) difficulty in stretching the contracted panels. Also, the considerable slope height resulted in some permanent ring deformation.

  • Corporate Authors:

    New York State Thruway Authority

    200 Southern Boulevard, P.O. Box 189
    Albany, NY  United States  12201-0189
  • Authors:
    • Fish, Marc
    • Badger, Thomas C
    • Lowell, S M
    • Journeaux, D
  • Conference:
  • Publication Date: 2009


  • English

Media Info

  • Media Type: CD-ROM
  • Features: Photos; Tables;
  • Pagination: pp 89-106
  • Monograph Title: Proceedings of the 60th Highway Geology Symposium

Subject/Index Terms

Filing Info

  • Accession Number: 01142306
  • Record Type: Publication
  • Files: TRIS
  • Created Date: Oct 20 2009 5:07PM