Avalanche Standards

What You Need to Know

There are two main sources for guidelines concerning the design of static defense structures for retaining snow masses in the initiation zone of avalanches: the ONR 24805 – 24807 guidelines published by Austrian Standards Institute and the technical guide by the Swiss Federal Institute for Snow and Avalanche Research. These documents contain information on how to design mitigation measures on a site-to-site basis. This is a very different approach than for rockfall catchment fences since site specific conditions and loading scenarios are the driving factors for designing the structure and layout of the systems and must be taken into consideration as needed.

ONR 24805 – 24807

ONR 24805, 24806, and 24807 are a series of comprehensive documents published by the Austrian Standards Institute that deal with avalanche control measures.

ONR 24805
The first of the series provides a foundation for discussion, defining terminology as well as describing the load conditions and assumptions acting on protection structures.

ONR 24806
This document outlines the design process for avalanche protection structures. It covers the how to plan, dimension and construct various types of structures, including flexible-net systems.

ONR 24807
The final document of this series describes the operational aspects of avalanche protection structures including their monitoring, inspection and maintenance.

WSL Design Guidelines

These guidelines are similar to the Austrian guidelines, but are specifically focused on static (starting zone) defense structures such as snow nets, snow rakes and snow bridges. It is a comprehensive guide that covers terminology, planning, dimensioning, and construction.


References

ASI (2010) ONR 24805: Permanent technical avalanche protection – Terms, definitions, statical and dynamic load assumptions . Austrian Standards Institute, Vienna, Austria.

ASI (2010) ONR 24807: Permanent technical protection against avalanches – Monitoring and maintenance. Austrian Standards Institute, Vienna, Austria.

ASI (2011) ONR 24806: Permanent technical avalanche protection – Design of structures. Austrian Standards Institute, Vienna, Austria.

WSL (2007) Defense structures in avalanche starting zones. Bern, Switzerland.