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The effect of terrain slope on firefighter safety zone effectiveness

Author(s): Bret W. Butler, Jason M. Forthofer, Kyle S. Shannon, Daniel M. Jimenez, David Frankman
Year Published: 2010

The current safety zone guidelines used in the US were developed based on the assumption that the fire and safety zone were located on flat terrain. The minimum safe distance for a firefighter to be from a flame was calculated as that corresponding to a radiant incident energy flux level of 7.0kW-m-2. Current firefighter safety guidelines are based on the assumption that radiant energy transfer is the dominant energy transfer mode. Intuition, professional observations, and the few experimental measurements that have been reported indicate that when fires are located on slopes or ridges convective energy transfer may reach distances equal to 2 to 4 or more flame lengths ahead of the fire front. This implies that the current safety zone guidelines may be invalid in some situations where the safety zone and/or fire are on slopes. A research project supported by the Joint Fire Science Program is underway to measure convective energy transport and use those measurements to develop safety zone guidelines for slopes. The new guidelines will depend on multiple variables including: fire characteristics (flame length or height), site characteristics (e.g. slope percent), and relative location (i.e. chimney, ridge, midslope, ridgetop).

Citation: Butler, B.; Forthofer, J.; Shannon, K.; Jimenez, D.; Frankman, D. 2010. The effect of terrain slope on firefighter safety zone effectiveness. In: Wade, Dale D.; Robinson, Mikel L., eds. Proceedings of 3rd Fire Behavior and Fuels Conference; 25-29 October 2010; Spokane, WA. Birmingham, AL: International Association of Wildland Fire. 6 p.
Topic(s): Fire Behavior, Fire Safety Zones
Ecosystem(s): None
Document Type: Conference Proceedings
NRFSN number: 16934
Record updated: May 18, 2018