Below is the uncorrected machine-read text of this chapter, intended to provide our own search engines and external engines with highly rich, chapter-representative searchable text of each book. Because it is UNCORRECTED material, please consider the following text as a useful but insufficient proxy for the authoritative book pages.
1 Guidelines for Certification and Management of Rockfall Fence Systems Rockfall fence systems have been in service along roadways in Europe and the United States for more than 40 years. In the United States, rockfalls occur each year along highways; consequently, rockfall fence systems have become an important component of highway safety and maintenance. Rockfall fence systems are usually designed and rated based on full-scale testing of energy capacity or energy reduction of a single rockfall event with some consideration for serviceability after specific impacts. Before 2003, no widely accepted means were available to test and certify flexible rock- fall fence systems sold in the United States. In 2003, the National Cooperative Highway Research Program (NCHRP) Project 20-07, Task 138, âRecommended Procedures for the Testing of Rock-Fall Barriersâ (Higgins 2003) was submitted to the American Association of State Highway and Transportation Officials (AASHTO). This task report recommended acceptance of the Swiss testing standard and certification process (Gerber 2001). In 2008, the European Union (EU) implemented standardized testing and certification of rockfall fences known as European Technical Approval Guideline (ETAG) 27. ETAG 27 differs from the Swiss standard making direct comparisons of test results reported from each standard more difficult. Most European manufacturers are certifying their products in accordance with ETAG 27 guidelines. Currently, U.S. transportation agencies do not have testing standards and certification pro- cedures for these flexible rockfall fence systems. Acceptance of the ETAG 27 test procedure is proposed for use within the United States, thus eliminating the need for manufacturers to perform additional testing. A form has been developed for agencies to request data collected during an ETAG 27 test from manufacturers so the agency can evaluate the system for confor- mance with a project-specific specification of the rockfall fence system performance. In addition, the long-term performance and maintenance issues of flexible rockfall fence systems are a growing concern for many transportation agencies that have installed these systems and are faced with significant maintenance, repair, and replacement costs. Currently, there are no well-defined provisions or protocols for inventory, condition assessment, and life-cycle modeling of rockfall fence systems. Asset management offers a framework for mon- itoring performance of rockfall fence systems and understanding the condition/deterioration timeline so that transportation agencies can make informed life-cycle cost-based decisions about these assets. Combining technical analysis with asset management principles can yield a more efficient and fiscally responsible transportation system that focuses on preservation of assets while maintaining the required level of service set by owners. Guidelines are presented for the inventory and condition assessment of flexible rockfall fence systems to collect the data necessary for transportation agencies to perform life-cycle and risk analysis to guide project evaluation and prioritization. S U M M A R Y