Development of standardized testing procedures for flexible rockfall fence systems

Abstract

Flexible rockfall fence systems, or rockfall barriers, are typically designed and rated for an energy capacity, and other parameters such as deflection, based on full-scale testing. These tests are conducted using a standard procedure for reproducibility of the tests such that various fences from the same or different manufacturers can be compared in terms of capacity, deflection, and other criteria. In 2003, the United States (U.S.) developed recommended procedures for testing rockfall fences. These were similar to a Swiss guideline that was widely used by European fence manufacturers. Also, the recommended U.S. guideline allowed substitution of testing conducted using the Swiss guideline. U.S. transportation agencies could then compare products whether they were tested in the U.S. or Europe. In 2008, the European Union (E.U.) developed a standardized rockfall testing guideline. European and some U.S. manufacturers of rockfall fences, usually with headquarters in Europe, are now certifying their products in accordance with the E.U. guideline. U.S. design and installation practice of fences differ in some important ways from European practice, and the E.U. guideline does not limit some fence characteristics important to common U.S. practice. Additionally, the E.U. guideline differs from the Swiss and recommended U.S. guidelines in several important ways. This can cause uncertainty for U.S. transportation agencies when choosing products tested using the E.U guideline. Through review of the development of various rockfall testing programs and procedures as well as surveying of transportation agencies, rockfall fence manufacturers, and design engineers, a proposed testing guideline for the U.S. has been developed. This guideline is based on the widely used E.U. guideline. Additionally, requirements for substitution of U.S. testing with E.U. testing are outlined to allow manufacturers to choose whether they test their products in the E.U. or U.S. and to ensure that fences installed in the U.S. are equivalent to those tested in the E.U. With this proposed guideline, U.S. transportation agencies will again have the ability to compare different rockfall fence systems whether they are tested in the U.S. or Europe.