Safe and economical rockfall protection barriers

Flexible wire net systems are an integral part of rockfall mitigation measures. In Switzerland they are often used to protect transportation lines as well as residential areas. A proper site analysis and the choice of the appropriate rockfall protection system are the key components to a safe and economic rockfall hazard analysis. Although wire nets have been well known as rockfall protection systems since the early sixties, no field testing was conducted before 1989 and little information was recorded on the capabilities of these systems. Extensive field testing of rockfall protection systems was carried out on three different locations in California and in Switzerland from 1989 till 1996. Many different designs were tested and improved with the goal to maximize safety and minimize maintenance needs. A result of the tests is an improved and advanced generation of ring net barriers which are capable of stopping rockfall energies in the range from 40 kJ to 2350 kJ. Rockfall impact energies were analysed and the response and behaviour of the systems studied. The detailed analysis of rock deceleration in the barrier allows the calculation of the distribution of the impact forces in the system components. Future measurements of anchor forces provide basic data for the dimensioning of systems for inter- and extrapolation.